Carbapenem-resistant Enterobacteriaceae (CRE) are listed as a priority-one critical pathogen category by the WHO because of their abysmal treatment outcomes owing to antibiotic inefficiency. Among CRE, Klebsiella pneumoniae is prevalent in acquiring resistance genes and withstanding the last-resort drugs. Additionally, its ability to form robust biofilms further exacerbates the treatment challenges. The escalating resistance and recalcitrance of biofilm-residing bacteria against standard antibiotic treatments demand an alternative to antibiotics. Phages, being nature-tailored, are a never-ending arsenal against the bacteria because of their capacity to lyse bacteria rapidly and co-evolve with bacteria. In our study, we isolated K. pneumoniae from patients at Madras Medical Mission Hospital (MMMH), India, and assessed their antibiogram profiles, presence of carbapenemase genes, and biofilm-forming abilities. 100 % of the strains were extended-spectrum beta-lactamase producing, multidrug-resistant (ESBL-MDR), with 95 % harbouring carbapenemase genes. Among the isolates, 65 % were strong biofilm formers, and the rest were moderate. Further, we isolated a bacteriophage, SAKp11, from the hospital sewage, which was able to lyse 62 out of 167 clinical isolates and successfully reduced 99.99 % viable bacterial cells of the 24-h-old biofilm of strong biofilm forming MDR K. pneumoniae strains. Whole genome analysis revealed that SAKp11, with a genome size of 59,338bp, belonged to the Casjensviridae family, one of the less explored bacteriophage families. Comprehensive characterization of SAKp11 indicated its suitability for therapeutic use. Our study highlights the severity of drug-resistant K. pneumoniae in Indian healthcare and the inadequacy of current antibiotics, underscoring the potential of phages as an alternative therapeutic option.

Traumatic spine injury (TSI) is a prevalent condition that often requires surgical intervention. Two serious infectious complications after surgery are surgical site infections (SSI) and lower respiratory tract infections (LRTI). Yet, studies on SSI and LRTI on trauma patients, particularly with a specific focus on microbiology are lacking. The primary aim of this study is to investigate the prevalence rate of early SSI, occurring within one month of surgery or three months when instrumented, and LRTI in level-1 trauma center patients requiring surgery after TSI.

This monocenter retrospective observational study was conducted at an academic level-1 trauma center, including patients with TSI requiring surgery. Data on patients' baseline characteristics, trauma related information, initial and intra-operative management, infectious complications data and hospitalization outcomes were collected. The two primary outcomes were the prevalence of early SSI and LRTI. Secondary outcomes included the identification of factors associated with developing these infections, analysis of identified organisms, and assessment of clinical outcomes.

A total of 2606 patients were screened between May 2018 and October 2022, 194 were included. Most of them were polytrauma patients defined by Injury Severity Score ≥ 16 (71 %). Early SSI occurred in 20 patients (10 %) and LRTI occurred in 58 patients (30 %). The number of vertebral levels instrumented (odds ratio [OR] 1.24, 95 % confidence interval [95 % CI] 1.01-1.52) was associated with SSI. The causative organisms were predominantly Gram-positive cocci (19/36 identified organisms). Factors associated with LRTI were an injury severity score ≥ 25 (OR 7.41; 95 % CI, 3.28-17.99), spinal injury at levels C3-C7 (OR 2.24; 95 % CI 1.01-5.14) and antibiotics during initial management (OR 7.09; 95 % CI, 2.71-20.49). The causative organisms were predominantly Gram-negative bacilli (58/80 identified organisms). Patients with LRTI experienced longer hospital stays, extended durations of mechanical ventilation, and higher mortality rates at 30 days and one year than those without.

Early SSI and LRTI are underestimated complications in severe trauma patients with TSI requiring surgery. Identifying risk factors and causative organisms is an important step for advancing research on targeted prevention and treatment of SSI and LRTI after trauma.

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that is a leading cause of morbidity and mortality worldwide in susceptible patients, particularly in those with respiratory disorders. The rising prevalence of multidrug-resistant strains and the failure of previous P. aeruginosa vaccine candidates in clinical trials highlight the urgent need to investigate novel vaccine antigens. In this study, we evaluated the protective potential of two antigen candidates, LptH and OprM, previously identified based on their involvement in host-cell attachment in a murine acute pneumonia model. Recombinant Escherichia coli BL21 clones overexpressing these proteins showed 8.8- and 3.5-fold increased attachment to 16HBE14o- cells in vitro, confirming their role in host-cell attachment. Immunisation with rLptH significantly reduced bacterial burden in the lungs by 1.12 log10 CFU and improved animal welfare scores compared to adjuvant-only controls. Serological and immunophenotyping analyses revealed that the monovalent rLptH vaccine stimulated antigen-specific IgG1 and IgG2c isotype production, and enhanced IFN-γ and IL-17 recall responses in the spleen. Moreover, a trivalent vaccine comprising rLptH and two other P. aeruginosa antigens, rFtsZ, and rOpmH, achieved a 2.33 log10 CFU reduction in lung bacterial burden, and 1.85 log10 CFU reduction in dissemination. These encouraging findings support the potential of LptH as a promising antigen for the development of a protective multivalent vaccine against P. aeruginosa infections.

Klebsiella pneumoniae causes both community-acquired and healthcare-associated infections, presenting a major therapeutic challenge to global public health. RstBA is a common two-component regulatory system that controls downstream gene expression in certain Enterobacteriaceae species. However, the role of RstBA in K. pneumoniae infection remains unknown. To determine its function, a wild-type K. pneumoniae strain (ATCC43816) and rstA mutant and complementation strains were constructed. Phenotypic experiments and in vivo animal infection assays demonstrated that deletion of rstA decreased virulence and biofilm formation. RNA sequencing analysis of ATCC43816 and rstA mutant strains was performed to study the regulatory mechanisms, revealing differential expression of genes involved in arginine and proline metabolism, phenylalanine metabolism, and quorum sensing. In addition, the mrkI and the mrkABCDF gene cluster, which regulates and encodes type 3 fimbriae, exhibited lower expression in the absence of rstA, possibly related to decreased virulence and biofilm formation. Quantitative real-time reverse transcription PCR, promoter activity assays, and electrophoretic mobility shift assays were conducted to identify the transcriptional regulation of mrkI and mrkABCDF by rstA. Our findings show that rstA regulates type 3 fimbriae expression by regulating mrkI indirectly and regulating mrkA directly by binding to its promoter. This study provides new insights into the functional importance of RstA in regulating biofilm formation and virulence in K. pneumoniae.IMPORTANCEKlebsiella pneumoniae is an opportunistic pathogen that has become a significant cause of community-acquired and nosocomial infections. The rise of hypervirulent and multi-drug-resistant K. pneumoniae poses a significant threat to public health. The two-component regulatory system is a typical signal-sensing and stress-response system widely distributed in bacteria, playing a critical regulatory role in bacterial infection. Through in vivo and in vitro experiments, we demonstrate that rstA regulates the expression of type 3 fimbriae by regulating mrkI indirectly and mrkA directly, thereby playing an essential role in the virulence and biofilm formation of K. pneumoniae. Understanding the regulatory mechanism of RstA in K. pneumoniae provides a proof-of-concept for identifying new genetic targets for controlling K. pneumoniae infection, which may aid in the development of therapeutic drugs.

Ventilator-associated pneumonia (VAP), defined as a lung infection that occurs in patients after 48 hours on mechanical ventilation, is among the most frequently found nosocomial infections in intensive care units around the world and is associated with increased morbidity, mortality, and economic burden.

We review the classical mechanisms of VAP development and explore more recent ones, such as dysbiosis, which has changed our view of the pathogenesis of the disease; whereas in the past the lower respiratory tract was classically considered a sterile organ, the use of new diagnostic techniques has shown that the lungs of healthy humans are inhabited by a large, dynamic ecosystem of microorganisms. Dysbiosis is the disruption of this ecosystem and is a key factor in the development of VAP. Recent findings have demonstrated that host immunity is microbiome-regulated and, consequently, is profoundly affected by dysbiosis. In this paper the significance of the microbiome-immunity crosstalk in the pathophysiology of VAP will be discussed.

A deeper understanding of mechanisms of VAP pathogenesis should help to devise new preventive, diagnostic and therapeutic strategies for reducing the incidence of this condition and for improving patient prognosis.

Increased intra-abdominal pressure (IAP) is a significant clinical concern, which has been proven to cause significant adverse events in patients. Respiratory infections are a high-yield problem in the intensive care unit (ICU). In this study, we reviewed available literature regarding the relationship between elevated IAP and the development of ventilator-associated pneumonia (VAP) in mechanically ventilated patients. Patients with prolonged mechanical ventilation are prone to develop VAP. Longer hospitalization, prior use of antibiotics, and comorbidities make these patients more susceptible to infections. Multidrug-resistant VAP poses a vast threat to critically ill patients, as it is characterized by a shift in the microbiological profile of the disease, as well as difficulties in its treatment options. Elevated IAP could adversely affect mechanically ventilated patients, as it is associated with an elevated risk of microaspirations and altered patency of the intestinal barrier, thus comprising an important factor for developing VAP. In addition, elevated IAP can deteriorate pulmonary function and hemodynamic condition of the patient, adding an extra risk for developing VAP. In such frail conditions, these patients have compromised immune function and are at risk of developing systematic infection, even resulting in the failure of multiple organs. As the microbiologic profile shifts toward multidrug-resistant bacteria, there is a need for comprehensive strategies in ICU settings to mitigate the risks associated with both elevated IAP and multidrug-resistant VAP. Timely intervention and proper management can prevent the risk of difficult-to-treat infections and life-threatening adverse events for patients.

Respiratory tract infections (RTIs) are one of the leading causes of morbidity and mortality worldwide. The increase in antimicrobial resistance in respiratory pathogens poses a major challenge to the effective management of these infections.

To investigate the distribution of major pathogens of RTIs and their antimicrobial resistance patterns in a tertiary care hospital and to develop a mathematical model to explore the relationship between pathogen distribution and antimicrobial resistance.

Five hundred patients with RTIs were included in the study and 475 bacterial strains were isolated from their respiratory specimens. Antimicrobial susceptibility testing and analysis of influencing factors were performed. A mathematical model was developed to simulate the relationship between pathogen distribution and drug resistance.

The most common pathogens were Streptococcus pneumoniae (30%), Haemophilus influenzae (20%), Pseudomonas aeruginosa (15%), Staphylococcus aureus (10%) and Klebsiella pneumoniae (10%). The distribution of pathogens varied according to age group and type of RTIs, with higher proportions of Pseudomonas aeruginosa and Staphylococcus aureus in hospital-acquired and ventilator-associated pneumonia. Isolated pathogens showed high and increasing rates of resistance to commonly used antibiotics. Model simulations suggest that a shift in the distribution of pathogens toward more resistant strains may lead to a significant increase in overall resistance rates, even if antibiotic use patterns remain unchanged.

This study emphasizes the importance of regular monitoring of respiratory pathogen distribution and antimicrobial resistance patterns and the need for a comprehensive approach to managing RTIs, including implementation of antibiotic stewardship programs, infection control measures, and development of new therapies.

Introduction: Nosocomial lower respiratory tract infections (nLRTIs), including hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), remain significant challenges due to high mortality, morbidity, and healthcare costs. Implementing accurate and timely diagnostic strategies is pivotal for guiding optimized antimicrobial therapy and addressing the growing threat of antimicrobial resistance. Areas Covered: This review examines emerging microbiological diagnostic methods for nLRTIs. Although widely utilized, traditional culture-based techniques are hindered by prolonged processing times, limiting their clinical utility in timely decision-making. Advanced molecular tools, such as real-time PCR and multiplex PCR, allow rapid pathogen identification but are constrained by predefined panels. Metagenomic next-generation sequencing (mNGS) provides comprehensive pathogen detection and resistance profiling yet faces cost, complexity, and interpretation challenges. Non-invasive methods, including exhaled breath analysis using electronic nose (e-nose) technology, gene expression profiling, and biomarker detection, hold promise for rapid and bedside diagnostics but require further validation to establish clinical applicability. Expert Opinion: Integrating molecular, metagenomic, biomarker-associated, and traditional diagnostics is essential for overcoming limitations. Continued technological refinements and cost reductions will enable broader clinical implementation. These innovations promise to enhance diagnostic accuracy, facilitate targeted therapy, and improve patient outcomes while contributing to global efforts to mitigate antimicrobial resistance.

To develop a machine learning-based prediction model to assist clinicians in accurately determining whether the detection of Klebsiella pneumoniae (KP) in sputum samples indicates an infection, facilitating timely diagnosis and treatment.

A retrospective analysis was conducted on 8,318 patients with KP cultures admitted to a tertiary hospital in Northeast China from January 2019 to December 2023. After excluding duplicates, other specimen types, cases with substandard specimen quality, and mixed infections, 286 cases with sputum cultures yielding only KP were included, comprising 67 cases in the colonization group and 219 cases in the infection group. Antimicrobial susceptibility testing was performed on the included strains, and through univariate logistic regression analysis, 15 key influencing factors were identified, including: age > 62 years, ESBL, CRKP, number of positive sputum cultures for KP, history of tracheostomy, use of mechanical ventilation for >96 h, indwelling gastric tube, history of craniotomy, recent local glucocorticoid application, altered consciousness, bedridden state, diagnosed with respiratory infectious disease upon admission, electrolyte disorder, hypoalbuminemia, and admission to ICU (all p < 0.05). These factors were used to construct the model, which was evaluated using accuracy, precision, recall, F1 score, AUC value, and Brier score.

Antimicrobial susceptibility testing indicated that the resistance rates for penicillins, cephalosporins, carbapenems, and quinolones were significantly higher in the infection group compared to the colonization group (all p < 0.05). Six predictive models were constructed using 15 key influencing factors, including Classification and Regression Trees (CART), C5.0, Gradient Boosting Machines (GBM), Support Vector Machines (SVM), Random Forest (RF), and Nomogram. The Random Forest model performed best among all indicators (accuracy 0.93, precision 0.98, Brier Score 0.06, recall 0.72, F1 Score 0.83, AUC 0.99). The importance of each factor was demonstrated using mean decrease in Gini. "Admitted with a diagnosis of respiratory infectious disease" (8.39) was identified as the most important factor in the model, followed by "Hypoalbuminemia" (7.83), then "ESBL" (7.06), "Electrolyte Imbalance" (5.81), "Age > 62 years" (5.24), "The number of Positive Sputum Cultures for KP > 2" (4.77), and being bedridden (4.24). Additionally, invasive procedures (such as history of tracheostomy, use of ventilators for >96 h, and craniotomy) were also significant predictive factors. The Nomogram indicated that CRKP, presence of a nasogastric tube, admission to the ICU, and history of tracheostomy were important factors in determining KP colonization.

The Random Forest model effectively distinguishes between infection and colonization status of KP, while the Nomogram visually presents the predictive value of various factors, providing clinicians with a reference for formulating treatment plans. In the future, the accuracy of infection diagnosis can be further enhanced through artificial intelligence technology to optimize treatment strategies, thereby improving patient prognosis and reducing healthcare burdens.

Endotracheal suction catheters are often used multiple times during endotracheal suctioning procedures in resource-limited intensive care units (ICU). The impact of this practice on mechanically ventilated patients' outcomes remains unclear.

The aim of this feasibility randomized controlled trial (fRCT) is to assess the feasibility and acceptability of single-use versus multiple-use endotracheal suction catheters flushed with chlorhexidine in mechanically ventilated ICU patients.

This study is a three-armed fRCT with an embedded qualitative study.

The trial involves three groups. One group includes endotracheal suctioning using a single-use catheter; the second group includes a multiple-use endotracheal suction catheter flushed with chlorhexidine and the control group includes a multiple-use endotracheal suction catheter flushed with normal saline. Sixty adult ICU patients (20 in each group) will be recruited, along with 12-16 ICU nurses delivering the interventions, and 12-16 patients' next-of-kin for semi-structured interviews. The study protocol has been approved by two ethics committees. Study recruitment will be conducted over an 8-month period with an expected start date of 12 April 2024.

The feasibility outcome measures will be recruitment, retention, and follow-up measures as well as the identification of clinical outcomes such as Ventilator-Associated Pneumonia (VAP) using the modified clinical pulmonary infection score, and ICU length-of-stay.

This study will help ICU nurses to understand how different methods of endotracheal suctioning affects patients in ICUs with limited resources. The findings could influence clinical practice and improve patient outcomes.

Lower respiratory tract infections (LRTIs) are the most common infections in humans accounting for significant morbidity and mortality. Management of LRTIs is complicated due to increasing antimicrobial resistance. This study investigated the prevalence and trends of antimicrobial resistance for bacteria isolated from respiratory samples of patients with LRTIs.

Sputum and bronchial washings were collected from patients of all ages hospitalized with LRTIs and were analyzed by the microbiological laboratory in the University Hospital of Heraklion, Crete, Greece, from January 2017 to December 2022. Identification of the bacterial isolates was performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and antimicrobial susceptibility testing by Vitek 2 system.

A total of 4,008 strains were isolated from 3,427 respiratory samples. Acinetobacter baumannii was the most frequently isolated pathogen (23.1%), followed by Pseudomonas aeruginosa (20.0%), Staphylococcus aureus (10.6%) and Klebsiella pneumoniae (6.8%). The isolation rate of A. baumannii significantly increased during the study period, while there were lower increases in the isolation rates of P. aeruginosa, K. pneumoniae and S. aureus. A. baumannii and P. aeruginosa were more prevalent during summer, K. pneumoniae was more common during autumn, while for S. aureus higher incidence was noted during winter. A. baumannii exhibited high resistance rates (≥90.0%) to most of the antimicrobial agents tested, and extremely high multidrug-resistance (91.0%). P. aeruginosa showed the lowest rate of resistance for colistin (1.4%). Among β-lactams, resistance rates to piperacillin/tazobactam, ceftazidime, cefepime, imipenem and meropenem were 26.2%, 27%, 25.8%, 29.2% and 29.9%, respectively. A total of 162 (68.1%) meropenem-resistant P. aeruginosa were simultaneously resistant to ceftazidime and piperacillin/tazobactam. Regarding K. pneumoniae, high rates of resistance were observed for the third and fourth generation cephalosporins, namely cefotaxime, ceftriaxone, ceftazidime, and cefepime and the carbapenems, imipenem and meropenem ranging from 46.2% to 53.8%. Carbapenem-resistance was detected among 46.2% of the isolates. Among the 126 carbapenem-resistant K. pneumoniae isolates, 83 (65.9%), 30 (23.8%), 9 (7.2%), and 4 (4.2%) were positive for Klebsiella pneumoniae carbapenemase, New Delhi Metallo-β-lactamase, Verona Integron-Mediated Metallo-β-lactamase and OXA-48 carbapenemase, respectively. Of the total number of S. aureus, 37.2% were methicillin resistant. Low rates of resistance were detected in trimethoprim/sulfamethoxazole (3.3%), gentamicin (2.8%), and rifampicin (0.9%). All isolates were susceptible to linezolid, daptomycin, tigecycline, teicoplanin, and vancomycin.

Regularly updated surveillance of local microbial prevalence and monitoring of antimicrobial resistance patterns is of paramount importance to guide the empiric treatment of LRTIs.

Pseudomonas aeruginosa (P. aeruginosa)-induced pneumonia is marked by considerable infiltration of inflammatory cells and biofilm formation, which causes acute and transient lung inflammation and infection. Nevertheless, the discovery of alternative preventative and therapeutic methods is essential due to the high mortality rates in clinical settings and the resistance of P. aeruginosa infection to multiple medications.

In this research, we constructed amphiphilic Janus nanoparticles (JNPs, denoted as SSK1@PDA/CaP@CIP), loaded with hydrophobic SSK1, a β-galactosidase (β-gal)-activated prodrug for reducing macrophages, and hydrophilic ciprofloxacin (CIP), a classic antibiotic for treating infection. SSK1@PDA/CaP@CIP was designed to effectively attenuate inflammation, eradicate biofilms, and combat planktonic P. aeruginosa.

As expected, SSK1@PDA/CaP@CIP was able to target the infection site and demonstrated outstanding efficacy in treating P. aeruginosa strain PAO1-induced pneumonia by regulating macrophage infiltration to reduce inflammation and removing planktonic bacteria and biofilms to control infection. Additionally, the primary organs did not exhibit any discernible pathological changes following treatment with SSK1@PDA/CaP@CIP, which indicates superior biocompatibility throughout the treatment course.

In conclusion, our investigation introduced a promising approach to the treatment of pneumonia associated with PAO1.

Serratia marcescens is an opportunistic human pathogen that causes urinary tract infections, ocular lens infections, and respiratory tract infections. S. marcescens employs various defense mechanisms to evade antibiotics, one of which is mediated by aminoglycoside N-acetyltransferase (AAC). In this mechanism, the enzyme AAC facilitates the transfer and linkage of the acetyl moiety from the donor substrate acetyl-coenzyme A to specific positions on antibiotics. This modification alters the antibiotic's structure, leading to the inactivation of aminoglycoside antibiotics. In the current scenario, antibiotic resistance has become a global threat, and targeting the enzymes that mediate resistance is considered crucial to combat this issue. The study aimed to address the increasing global threat of antibiotic resistance in Serratia marcescens by targeting the aminoglycoside N-acetyltransferase (AAC (6')) enzyme, which inactivates aminoglycoside antibiotics through acetylation. Due to the absence of experimental structure, we constructed a homology model of aminoglycoside N (6')-acetyltransferase (AAC (6')) of S. marcescens using the atomic structure of aminoglycoside N-acetyltransferase AAC (6')-Ib (PDB ID: 1V0C) as a template. The stable architecture and integrity of the modelled AAC (6') structure were analyzed through a 100 ns simulation. Structure-guided high-throughput screening of four small molecule databases (Binding, Life Chemicals, Zinc, and Toslab) resulted in the identification of potent inhibitors against AAC (6'). The hits obtained from screening were manually clustered, and the five hit molecules were shortlisted based on the docking score, which are observed in the range of -17.09 kcal/mol to -11.95 kcal/mol. These selected five molecules displayed acceptable pharmacological properties in ADME predictions. The binding free energy calculations, and molecular dynamics simulations of ligand bound AAC (6') complexes represented higher affinity and stable binding. The selected molecules demonstrated stable binding with AAC (6'), indicating their strong potential to hamper the binding of aminoglycoside in the respective site. and thereby inhibit. This process mitigates enzyme mediated AAC (6') activity on aminoglycosides and reverse the bactericidal function of aminoglycosides, and also this method could serve as a platform for the development of potential antimicrobials.

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP), coharboring hypervirulence and carbapenem-resistance genes mediated by plasmids, causes infections with extremely high mortality and seriously impacts public health. Exploring the transfer mechanisms of virulence/carbapenem-resistance plasmids, as well as the formation and evolution pathway of hv-CRKP is of great significance to the control of hv-CRKP infections.

In this study, we identified the predominant clone of hv-CRKP in China and elucidated its genomic characteristics and formation route based on 239 multicenter clinical K. pneumoniae isolates and 1014 GenBank genomes by using comparative genomic analysis. Further, we revealed the factors affecting the transfer of virulence plasmids, and explained the genetic foundation for the prevalence of Chinese predominant hv-CRKP clone.

ST11-KL64 is the predominant clone of hv-CRKP in China and primarily evolved from ST11-KL64 CRKP by acquiring the pLVPK-like virulence plasmid from hvKP. Significantly, the virulence gene cluster iroBCDN was lost in the virulence plasmid of ST11-KL64 hv-CRKP but existed in that of hvKP. Moreover, the absence of iroBCDN didn't decrease the virulence of hv-CRKP, which was proved by bacterial test, cell-interaction test and mice infection model. On the contrary, loss of iroBCDN was observed to regulate virulence/carbapenem-resistance plasmid transfer and oxidative stress-related genes in strains and thus promoted the mobilization of nonconjugative virulence plasmid from hvKP into ST11-KL64 CRKP, forming hv-CRKP which finally had elevated antioxidant capacity and enhanced survival capacity in macrophages. The loss of iroBCDN increased the survival ability of hv-CRKP without decreasing its virulence, endowing it with an evolutionary advantage.

Our work provides new insights into the key role of iroBCDN loss in convergence of CRKP and hvKP, and the genetic and biological foundation for the widespread prevalence of ST11-KL64 hv-CRKP in China.

Staphylococcus aureus is a pathogen associated with severe respiratory infections. The ability of S. aureus to internalize into lung epithelial cells complicates the treatment of respiratory infections caused by this bacterium. In the intracellular environment, S. aureus can avoid elimination by the immune system and the action of circulating antibiotics. Consequently, interfering with S. aureus internalization may represent a promising adjunctive therapeutic strategy to enhance the efficacy of conventional treatments. Here, we investigated the host-pathogen molecular interactions involved in S. aureus internalization into human lung epithelial cells. Lipid raft-mediated endocytosis was identified as the main entry mechanism. Thus, bacterial internalization was significantly reduced after the disruption of lipid rafts with methyl-β-cyclodextrin. Confocal microscopy confirmed the colocalization of S. aureus with lipid raft markers such as ganglioside GM1 and caveolin-1. Adhesion of S. aureus to α5β1 integrin on lung epithelial cells via fibronectin-binding proteins (FnBPs) was a prerequisite for bacterial internalization. A mutant S. aureus strain deficient in the expression of alpha-hemolysin (Hla) was significantly impaired in its capacity to enter lung epithelial cells despite retaining its capacity to adhere. This suggests a direct involvement of Hla in the bacterial internalization process. Among the receptors for Hla located in lipid rafts, caveolin-1 was essential for S. aureus internalization, whereas ADAM10 was dispensable for this process. In conclusion, this study supports a significant role of lipid rafts in S. aureus internalization into human lung epithelial cells and highlights the interaction between bacterial Hla and host caveolin-1 as crucial for the internalization process.

Causative pathogens are currently identified in only a minority of pneumonia cases, which affects antimicrobial stewardship. Metagenomic next-generation sequencing (mNGS) has potential to enhance pathogen detection due to its sensitivity and broad applicability. However, while studies have shown improved sensitivity compared with conventional microbiological methods for pneumonia diagnosis, it remains unclear whether this can translate into clinical benefit. Most existing studies focus on patients who are ventilated, readily allowing for analysis of bronchoalveolar lavage fluid (BALF). The impact of sample type on the use of metagenomic analysis remains poorly defined. Similarly, previous studies rarely differentiate between the types of pneumonia involved-community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), or ventilator-associated pneumonia (VAP)-which have different clinical profiles.

This study aims to determine the clinical use of mNGS in CAP, HAP, and VAP, compared with traditional microbiological methods.

We aim to review all studies (excluding case reports of a series of fewer than 10 people) of adult patients with suspected or confirmed pneumonia that compare metagenomic analysis with traditional microbiology techniques, including culture, antigen-based testing, and polymerase chain reaction-based assays. Relevant studies will be identified through systematic searches of the Embase, MEDLINE, Scopus, and Cochrane CENTRAL databases. Screening of titles, abstracts, and subsequent review of eligible full texts will be done by 2 separate reviewers (SQ and 1 of AL, CJ, or CH), with a third clinician (ES) providing adjudication in case of disagreement. Our focus is on the clinical use of metagenomics for patients with CAP, HAP, and VAP. Data extracted will focus on clinically important outcomes-pathogen positivity rate, laboratory turnaround time, impact on clinical decision-making, length of stay, and 30-day mortality. Subgroup analyses will be performed based on the type of pneumonia (CAP, HAP, or VAP) and sample type used. The risk of bias will be assessed using the QUADAS-2 tool for diagnostic accuracy studies. Outcome data will be combined in a random-effects meta-analysis, and where this is not possible, a narrative synthesis will be undertaken.

The searches were completed with the assistance of a medical librarian on January 13, 2024, returning 5750 records. Screening and data extraction are anticipated to be completed by September 2024.

Despite significant promise, the impact of metagenomic analysis on clinical pathways remains unclear. Furthermore, it is unclear whether the use of this technique will alter depending on whether the pneumonia is a CAP, HAP, or VAP or the sample type that is collected. This systematic review will assess the current evidence base to support the benefit of clinical outcomes for metagenomic analysis, depending on the setting of pneumonia diagnosis or specimen type used. It will identify areas where further research is needed to advance this methodology into routine care.

PROSPERO CRD42023488096; https://tinyurl.com/3suy7cma.

DERR1-10.2196/57334.

Acinetobacter baumannii can cause prolonged infections that disproportionately affect immunocompromised populations. Our understanding of A. baumannii respiratory pathogenesis relies on an acute murine infection model with limited clinical relevance that employs an unnaturally high number of bacteria and requires the assessment of bacterial load at 24-36 hours post-infection. Here, we demonstrate that low intranasal inoculums in immunocompromised mice with a tlr4 mutation leads to reduced inflammation, allowing for persistent infections lasting at least 3 weeks. Using this "chronic infection model," we determined the adhesin InvL is an imperative virulence factor required during later stages of infection, despite being dispensable in the early phase. We also demonstrate that the chronic model enables the distinction between antibiotics that, although initially reduce bacterial burden, either lead to complete clearance or result in the formation of bacterial persisters. To illustrate how our model can be applied to study polymicrobial infections, we inoculated mice with an active A. baumannii infection with Staphylococcus aureus or Klebsiella pneumoniae. We found that S. aureus exacerbates the infection, while K. pneumoniae enhances A. baumannii clearance. In all, the chronic model overcomes some limitations of the acute pulmonary model, expanding our capabilities to study of A. baumannii pathogenesis and lays the groundwork for the development of similar models for other important opportunistic pathogens.

Evaluate associations between volatile organic compounds (VOCs) in heat and moisture exchange (HME) filters and the presence of ventilator-associated pneumonia (VAP).

Clinical diagnostic criteria for VAP have poor interobserver reliability, and cultures are slow to result. Exhaled breath contains VOCs related to gram-negative bacterial proliferation, the most identified organisms in VAP. We hypothesized that exhaled VOCs on HME filters can predict nascent VAP in mechanically ventilated intensive care unit patients.

Gas chromatography-mass spectrometry was used to analyze 111 HME filters from 12 intubated patients who developed VAP. Identities and relative amounts of VOCs were associated with dates of clinical suspicion and culture confirmation of VAP. Matched pairs t tests were performed to compare VOC abundances in HME filters collected within 3 days pre and postclinical suspicion of VAP (pneumonia days), versus outside of these days (non-pneumonia days). A receiver operating characteristic curve was generated to determine the diagnostic potential of VOCs.

Carbon disulfide, associated with the proliferation of certain gram-negative bacteria, was found in samples collected during pneumonia days for 11 of 12 patients. Carbon disulfide levels were significantly greater ( P = 0.0163) for filters on pneumonia days. The Area Under the Curve of the Reciever Operating Characteristic curve (AUC ROC) for carbon disulfide was 0.649 (95% CI: 0.419-0.88).

Carbon disulfide associated with gram-negative VAP can be identified on HME filters up to 3 days before the initial clinical suspicion, and approximately a week before culture confirmation. This suggests VOC sensors may have potential as an adjunctive method for early detection of VAP.

Quorum sensing (QS) inhibition has emerged as a promising target for directed drug design, providing an appealing strategy for developing antimicrobials, particularly against infections caused by drug-resistant pathogens. In this study, we designed and synthesized a total of 33 β-nitrostyrene derivatives using 1-nitro-2-phenylethane (NPe) as the lead compound, to target the facultative anaerobic bacterial pathogen Serratia marcescens. The QS-inhibitory effects of these compounds were evaluated using S. marcescens NJ01 and the reporter strain Chromobacterium violaceum CV026. Among the 33 new β-nitrostyrene derivatives, (E)-1-methyl-4-(2-nitrovinyl)benzene (m-NPe, compound 28) was proven to be a potent inhibitor that reduced biofilm formation of S. marcescens NJ01 by 79%. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) results revealed that treatment with m-NPe (50 μg/ml) not only enhanced the susceptibility of the formed biofilms but also disrupted the architecture of biofilms by 84%. m-NPe (50 μg/ml) decreased virulence factors in S. marcescens NJ01, reducing the activity of protease, prodigiosin, and extracellular polysaccharide (EPS) by 36%, 72%, and 52%, respectively. In S. marcescens 4547, the activities of hemolysin and EPS were reduced by 28% and 40%, respectively, outperforming the positive control, vanillic acid (VAN). The study also found that the expression levels of QS- and biofilm-related genes (flhD, fimA, fimC, sodB, bsmB, pigA, pigC, and shlA) were downregulated by 1.21- to 2.32-fold. Molecular dynamics analysis showed that m-NPe could bind stably to SmaR, RhlI, RhlR, LasR, and CviR proteins in a 0.1 M sodium chloride solution. Importantly, a microscale thermophoresis (MST) test revealed that SmaR could be a target protein for the screening of a quorum sensing inhibitor (QSI) against S. marcescens. Overall, this study highlights the efficacy of m-NPe in suppressing the virulence factors of S. marcescens, identifying it as a new potential QSI and antibiofilm agent capable of restoring or improving antimicrobial drug sensitivity.

The objective of the current study was to evaluate the interaction between Tunisian Thymus capitatus essential oil (EO) and cefotaxime against Extended-Spectrum Beta-lactamases (ESBLs) producing Klebsiella pneumoniae hospital strains. GC-MS revealed that the major component of EO was found to be carvacrol (69.28%). The EO exerts an advanced bactericidal effect against all strains. Synergy between EO and cefotaxime was obtained by combined disk diffusion and checkerboard techniques. Combined use of EO and cefotaxime reduced the MIC of imipenem by 8- to 128-fold for all strains (fractional inhibitory concentration index ˂ 0.5, synergy). The time kill curve assay confirmed the advanced activity of combinatory effects of EO and cefotaxime, with total reduce of bacterial number (CFU/mL) after 6 h of culture. Synergistic activity of the combination between EO and cefotaxime constitute an important strategy as therapeutical option to combat infections caused by ESBLs producing Klebsiella pneumoniae.

This article summarizes the characterization, by shotgun proteomics, of 11 bacterial strains identified as responsible for seafood spoilage. A total of 4455 peptide spectrum matches, corresponding to 4299 peptides and 3817 proteins were identified. Analyses of data determined the functional pathways they are involved in. The proteins identified were integrated into a protein-protein network that involves 371 nodes and 3016 edges. Those proteins are implicated in energy pathways, peptidoglycan biosynthesis, spermidine/putrescine metabolism. An additional 773 peptides were characterized as virulence factors, that participates in bacterial pathogenesis; while 14 peptides were defined as biomarkers, as they can be used to differentiate the bacterial species present. This report represents the most extensive proteomic repository available in the field of seafood spoilage bacteria; the data substantially advances the understanding of seafood decay, as well as provides fundamental bases for the recognition of the bacteria existent in seafood that cause spoilage during food processing/storage.

Non-ventilated hospital-acquired pneumonia (NV-HAP) is associated with a significant healthcare burden, arising from high incidence and associated morbidity and mortality. However, accurate identification of cases remains challenging. At present, there is no gold-standard test for the diagnosis of NV-HAP, requiring instead the blending of non-specific signs and investigations. Causative organisms are only identified in a minority of cases. This has significant implications for surveillance, patient outcomes and antimicrobial stewardship. Much of the existing research in HAP has been conducted among ventilated patients. The paucity of dedicated NV-HAP research means that conclusions regarding diagnostic methods, pathology and interventions must largely be extrapolated from work in other settings. Progress is also limited by the lack of a widely agreed definition for NV-HAP. The diagnosis of NV-HAP has large scope for improvement. Consensus regarding a case definition will allow meaningful research to improve understanding of its aetiology and the heterogeneity of outcomes experienced by patients. There is potential to optimize the role of imaging and to incorporate novel techniques to identify likely causative pathogens. This would facilitate both antimicrobial stewardship and surveillance of an important healthcare-associated infection. This narrative review considers the utility of existing methods to diagnose NV-HAP, with a focus on the significance and challenge of identifying pathogens. It discusses the limitations in current techniques, and explores the potential of emergent molecular techniques to improve microbiological diagnosis and outcomes for patients.

Klebsiella pneumoniae poses a significant healthcare challenge due to its multidrug resistance and diverse serotype landscape. This study aimed to explore the serotype diversity of 1072 K. pneumoniae and its association with geographical distribution, disease severity and antimicrobial/virulence patterns in India. Whole-genome sequencing was performed on the Illumina platform, and genomic analysis was carried out using the Kleborate tool. The analysis revealed a total of 78 different KL types, among which KL64 (n=274/1072, 26 %), KL51 (n=249/1072, 24 %), and KL2 (n=88/1072, 8 %) were the most prevalent. In contrast, only 13 distinct O types were identified, with O1/O2v1 (n=471/1072, 44 %), O1/O2v2 (n=353/1072, 33 %), and OL101 (n=66/1072, 6 %) being the predominant serotypes. The study identified 114 different sequence types (STs) with varying serotypes, with ST231 being the most predominant. O serotypes were strongly linked with STs, with O1/O2v1 predominantly associated with ST231. Simpson's diversity index and Fisher's exact test revealed higher serotype diversity in the north and east regions, along with intriguing associations between specific serotypes and resistance profiles. No significant association between KL or O types and disease severity was observed. Furthermore, we found the specific association of virulence factors yersiniabactin and aerobactin (P<0.05) with KL types but no association with O antigen types (P>0.05). Conventionally described hypervirulent clones (i.e. KL1 and KL2) in India lacked typical virulent markers (i.e. aerobactin), contrasting with other regional serotypes (KL51). The cumulative distribution of KL and O serotypes suggests that future vaccines may have to include either ~20 KL or four O types to cover >85 % of the carbapenemase-producing Indian K. pneumoniae population. The results highlight the necessity for comprehensive strategies to manage the diverse landscape of K. pneumoniae strains across different regions in India. Understanding regional serotype dynamics is pivotal for targeted surveillance, interventions, and tailored vaccine strategies to tackle the diverse landscape of K. pneumoniae infections across India. This article contains data hosted by Microreact.

Carbapenem-resistant (Car-R) Pseudomonas aeruginosa is an urgent threat. These isolates may remain susceptible to traditional noncarbapenem antipseudomonal β-lactams, but it is unclear if carbapenem resistance impacts the effectiveness of these agents.

The purpose of this study was to compare clinical outcomes in Car-R and cephalosporin-susceptible (Ceph-S) P. aeruginosa pneumonia treated with cefepime versus other susceptible agents.

This retrospective cohort study evaluated patients diagnosed with hospital-acquired or ventilator-associated pneumonia who had a respiratory isolate of Car-R Ceph-S P. aeruginosa. Patients were excluded if they had polymicrobial respiratory cultures, other concomitant infections, empyema, death within 3 days of index culture, or received less than 3 days of susceptible therapy. Patients treated with cefepime were compared to other susceptible therapies. The primary endpoint was 30-day in-hospital mortality.

Eighty-seven patients were included: cefepime, n = 61; other susceptible therapies, n = 26. There were no differences in 30-day in-hospital mortality between cefepime and other susceptible therapies (19.6% vs. 19.2%, p value = 0.719). In addition, there were no differences between clinical cure rates (cefepime 65.6% vs. other therapies 72 %, p value = 0.47). In multivariate logistic regression, treatment with cefepime (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.11-2.52) was not independently associated with 30-day in-hospital mortality.

For the treatment of Car-R Ceph-S P. aeruginosa pneumonia, cefepime showed similar rates of 30-day in-hospital mortality and clinical outcomes when compared to other susceptible therapies. Cefepime may be utilized to conserve novel β-lactam and β-lactamase inhibitors.

The ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella Pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) is a group of bacteria very difficult to treat due to their high ability to acquire resistance to antibiotics and are the main cause of nosocomial infections worldwide, posing a threat to global public health. Nosocomial infections with MDR bacteria are found mainly in Intensive Care Units, due to the multitude of maneuvers and invasive medical devices used, the prolonged antibiotic treatments, the serious general condition of these critical patients, and the prolonged duration of hospitalization.

During a period of one year, from January 2023 to December 2023, this cross-sectional study was conducted on patients diagnosed with sepsis admitted to the Intensive Care Unit of the Sibiu County Emergency Clinical Hospital. Samples taken were tracheal aspirate, catheter tip, pharyngeal exudate, wound secretion, urine culture, blood culture, and peritoneal fluid.

The most common bacteria isolated from patients admitted to our Intensive Care Unit was Klebsiella pneumoniae, followed by Acinetobacter baumanii and Pseudomonas aeruginosa. Gram-positive cocci (Enterococcus faecium and Staphilococcus aureus) were rarely isolated. Most of the bacteria isolated were MDR bacteria.

The rise of antibiotic and antimicrobial resistance among strains in the nosocomial environment and especially in Intensive Care Units raises serious concerns about limited treatment options.

The worldwide increase of multidrug-resistant Gram-negative bacteria is a global threat. The emergence and global spread of Klebsiella pneumoniae carbapenemase- (KPC-) producing Klebsiella pneumoniae represent a particular concern. This pathogen has increased resistance and abilities to persist in human reservoirs, in hospital environments, on medical devices, and to generate biofilms. Mortality related to this microorganism is high among immunosuppressed oncological patients and those with multiple hospitalizations and an extended stay in intensive care. There is a severe threat posed by the ability of biofilms to grow and resist antibiotics. Various nanotechnology-based strategies have been studied and developed to prevent and combat serious health problems caused by biofilm infections. The aim of this review was to evaluate the implications of nanotechnology in eradicating biofilms with KPC-producing Klebsiella pneumoniae, one of the bacteria most frequently associated with nosocomial infections in intensive care units, including in our department, and to highlight studies presenting the potential applicability of TiO2 nanocomposite materials in hospital practice. We also described the frequency of the presence of bacterial biofilms on medical surfaces, devices, and equipment. TiO2 nanocomposite coatings are one of the best long-term options for antimicrobial efficacy due to their biocompatibility, stability, corrosion resistance, and low cost; they find their applicability in hospital practice due to their critical antimicrobial role for surfaces and orthopedic and dental implants. The International Agency for Research on Cancer has recently classified titanium dioxide nanoparticles (TiO2 NPs) as possibly carcinogenic. Currently, there is an interest in the ecological, non-toxic synthesis of TiO2 nanoparticles via biological methods. Biogenic, non-toxic nanoparticles have remarkable properties due to their biocompatibility, stability, and size. Few studies have mentioned the use of nanoparticle-coated surfaces as antibiofilm agents. A literature review was performed to identify publications related to KPC-producing Klebsiella pneumoniae biofilms and antimicrobial TiO2 photocatalytic nanocomposite coatings. There are few reviews on the antibacterial and antibiofilm applications of TiO2 photocatalytic nanocomposite coatings. TiO2 nanoparticles demonstrated marked antibiofilm activity, but being nano in size, these nanoparticles can penetrate cell membranes and may initiate cellular toxicity and genotoxicity. Biogenic TiO2 nanoparticles obtained via green, ecological technology have less applicability but are actively investigated.

The ongoing spread of antimicrobial resistance has complicated the treatment of bacterial hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Gram-negative pathogens, especially those with multidrug-resistant profiles, including Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Pseudomonas aeruginosa, and Acinetobacter spp., are important culprits in this type of infections. Understanding the determinants of resistance in pathogens causing pneumonia is ultimately stressing, especially in the shadows of the COVID-19 pandemic, when bacterial lung infections are considered a top priority that has become urgent to revise. Globally, the increasing prevalence of these pathogens in respiratory samples represents a significant infection challenge, with major limitations of treatment options and poor clinical outcomes. This review will focus on the epidemiology of HAP and VAP and will present the roles and the antimicrobial resistance patterns of implicated multidrug-resistant (MDR) Gram-negative pathogens like carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), carbapenem-resistant Enterobacterales (CRE), as well as colistin-resistant Gram-negative pathogens and extended-spectrum β-lactamase (ESBL)-producing Enterobacterales. While emerging from the COVID-19 pandemic, perspectives and conclusions are drawn from findings of HAP and VAP caused by MDR Gram-negative bacteria in patients with COVID-19.

The enormous potential attributed to prodigiosin regarding its applicability as a natural pigment and pharmaceutical agent justifies the development of sound bioprocesses for its production. Using a Serratia rubidaea strain isolated from a shallow-water hydrothermal vent, optimization of the growth medium composition was carried out. After medium development, the bacterium temperature, light and oxygen needs were studied, as was growth inhibition by product concentration. The implemented changes led to a 13-fold increase in prodigiosin production in a shake flask, reaching 19.7 mg/L. The conditions allowing the highest bacterial cell growth and prodigiosin production were also tested with another marine strain: S. marcescens isolated from a tide rock pool was able to produce 15.8 mg/L of prodigiosin. The bioprocess with S. rubidaea was scaled up from 0.1 L shake flasks to 2 L bioreactors using the maintenance of the oxygen mass transfer coefficient (kLa) as the scale-up criterion. The implemented parameters in the bioreactor led to an 8-fold increase in product per biomass yield and to a final concentration of 293.1 mg/L of prodigiosin in 24 h.

Colistimethate sodium (CMS) nebulization is associated with reduced systemic toxicity compared to intravenous injection, with potentially enhanced clinical efficacy. This study aimed to assess the pharmacokinetic (PK) properties of colistin during low-dose CMS nebulization in patients with ventilator-associated pneumonia (VAP) caused by carbapenem-resistant Acinetobacter baumannii. A nonlinear mixed-effects modeling approach was applied to develop population PK models for colistin in both epithelial lining fluid (ELF) and plasma. Twenty patients participated, and 80 ELF and 100 plasma samples were used for model development. Median colistin concentrations measured in ELF were 614-fold, 408-fold, and 250-fold higher than in plasma at 1, 3, and 5 h, respectively. Time courses in both ELF and plasma were best described by a one-compartment model with a Weibull absorption process. When the final model was simulated, the maximum free concentration and area under the free colistin concentration-time curve at steady state over 24 h in the plasma were approximately 1/90 and 1/50 of the corresponding values in ELF at steady state, respectively. For an A. baumannii MIC of 1 mg/L, inhaling 75 mg of CMS at 6 h intervals was deemed appropriate, with dose adjustments needed for MICs exceeding 2 mg/L. Using a nebulizer for CMS resulted in a notably higher exposure of colistin in the ELF than plasma, indicating the potential of nebulization to reduce systemic toxicity while effectively treating VAP.

Pseudomonas aeruginosa is an important cause of lower respiratory tract infections, such as ventilator-associated bacterial pneumonia (VABP). Using inhaled antibiotics to treat VABP can achieve high drug concentrations at the infection site while minimizing systemic toxicities. Despite the theoretical advantages, clinical trials have failed to show a benefit for inhaled antibiotic therapy in treating VABP. A potential reason for this discordance is the presence of biofilm-embedded bacteria in lower respiratory tract infections. Drug selection and dosing are often based on data from bacteria grown planktonically. In the present study, an in vitro air-liquid interface pharmacokinetic/pharmacodynamic biofilm model was optimized to evaluate the activity of simulated epithelial lining fluid exposures of inhaled and intravenous doses of polymyxin B and tobramycin against two P. aeruginosa strains. Antibiotic activity was also determined against the P. aeruginosa strains grown planktonically. Our study revealed that inhaled antibiotic exposures were more active than their intravenous counterparts across biofilm and planktonic populations. Inhaled exposures of polymyxin B and tobramycin exhibited comparable activity against planktonic P. aeruginosa. Although inhaled polymyxin B exposures were initially more active against P. aeruginosa biofilms (through 6 h), tobramycin was more active by the end of the experiment (48 h). Together, these data slightly favor the use of inhaled tobramycin for VABP caused by biofilm-forming P. aeruginosa that are not resistant to either antibiotic. The optimized in vitro air-liquid interface pharmacokinetic/pharmacodynamic biofilm model may be beneficial for the development of novel anti-biofilm agents or to optimize antibiotic dosing for infections such as VABP.

Patients with influenza infection during their period of admission may have worse computed tomography (CT) manifestation according to the clinical status. This study aimed to evaluate the CT findings of in-hospital patients due to clinically significant influenza pneumonia with correlation of clinical presentations.

In this retrospective, single center case series, 144 patients were included. All in-hospital patients were confirmed influenza infection and underwent CT scan. These patients were divided into three groups according to the clinical status of the most significant management: (1) without endotracheal tube and mechanical ventilator (ETTMV) or extracorporeal membrane oxygenation (ECMO); (2) with ETTMV; (3) with ETTMV and ECMO. Pulmonary opacities were scored according to extent. Spearman rank correlation analysis was used to evaluate the correlation between clinical parameters and CT scores.

The predominant CT manifestation of influenza infection was mixed ground-glass opacity (GGO) and consolidation with both lung involvement. The CT scores were all reach significant difference among all three groups (8.73 ± 6.29 vs 12.49 ± 6.69 vs 18.94 ± 4.57, p < 0.05). The chest CT score was correlated with age, mortality, and intensive care unit (ICU) days (all p values were less than 0.05). In addition, the CT score was correlated with peak lactate dehydrogenase (LDH) level and peak C-reactive protein (CRP) level (all p values were less than 0.05). Concomitant bacterial infection had higher CT score than primary influenza pneumonia (13.02 ± 7.27 vs 8.95 ± 5.99, p < 0.05).

Thin-section chest CT scores correlated with clinical and laboratory parameters in in-hospital patients with influenza pneumonia.

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

We sought to analyse the antibiotic susceptibility profiles and molecular epidemiology of MDR clinical Pseudomonas aeruginosa isolates from South India using non-MDR isolates as a reference.

We established a comprehensive clinical strain library consisting of 58 isolates collected from patients across the South Indian state of Kerala from March 2017 to July 2019. The strains were subject to antibiotic susceptibility testing, modified carbapenem inactivation method assay for carbapenemase production, PCR sequencing, comparative sequence analysis and quantitative PCR of MDR determinants associated with antibiotic efflux pump systems, fluoroquinolone resistance and carbapenem resistance. We performed in silico modelling of MDR-specific SNPs.

Of our collection of South Indian P. aeruginosa clinical isolates, 74.1% were MDR and 55.8% were resistant to the entire panel of antibiotics tested. All MDR isolates were resistant to levofloxacin and 93% were resistant to meropenem. We identified seven distinct, MDR-specific mutations in nalD, three of which are novel. mexA was significantly overexpressed in strains that were resistant to the entire test antibiotic panel while gyrA and gyrB were overexpressed in MDR isolates. Mutations in fluoroquinolone determinants were significantly associated with MDR phenotype and a novel GyrA Y100C substitution was observed. Carbapenem resistance in MDR isolates was associated with loss-of-function mutations in oprD and high prevalence of NDM (blaNDM-1) within our sample.

This study provides insight into MDR mechanisms adopted by P. aeruginosa clinical isolates, which may guide the potential development of therapeutic regimens to improve clinical outcomes.

This study on bacteremic nosocomial pneumonia (bNP) demonstrates the importance of this condition both in patients undergoing and not undergoing mechanical ventilation. Staphylococcus aureus, Enterobacterales, and non-fermenting Gram-negative bacilli are all causative agents in ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP), with a predominance of S. aureus in HAP and of Pseudomonas aeruginosa in VAP. Mortality in this condition is very high. Therefore, new therapeutic and preventive approaches should be sought.

Endotracheal suctioning of mechanically ventilated patients differs across the world. In many low and middle-income countries, endotracheal suctioning is often performed with a sterile suctioning catheter that is used for 12 h or during the length of one nursing shift. The effect of flushing multiple used endotracheal suction system with chlorhexidine after suctioning to reduce ventilator associated pneumonia (VAP) remains unclear.

The aim of the study is to assess the effectiveness of flushing multiple-used open endotracheal suction catheters and suctioning system with chlorhexidine gluconate 0.2% to reduce VAP in mechanically ventilated patients in a resource-limited Intensive Care Unit (ICU).

Due to the difficulty of blinding the intervention for nurses who perform endo-tracheal suction procedures, we adopted a quasi-experimental method with a randomized controlled trial design. A sample of 136 ICU patients were allocated to the intervention (n = 68) or control group (n = 68) between May and November 2020. The intervention was flushing the multiple-used suction catheter and suction system with 40ml chlorhexidine gluconate 0.2% and in the control group we used normal saline to flush the catheter and suction system. The primary outcome was incidence of VAP and the cost of the flushing solutions was the secondary outcome measure.

Patients in the intervention group had a lower incidence of VAP compared to patients in the control group; 15 (22.1%) vs 29 (42.6%), p = 0.01. The incidence of late-onset VAP was 26.2% in the intervention group and 49% in the control group (p = 0.026) and the early-onset VAP was 13.2% in the intervention group and 25% in the control group (p = 0.081). Chlorhexidine gluconate 0.2% reduced the cost of suction system flushing (median: 78.4 vs 300 EGP, p < 0.001).

Using chlorhexidine gluconate 0.2% to flush multiple-used suctioning catheters after every endo-tracheal suction procedure might reduce the incidence of VAP in mechanically ventilated patients. Chlorhexidine gluconate 0.2% can be a cost-effective solution for flushing the suction circuit. Nurses working in resource-limited ICUs and using suctioning catheters multiple times might consider using chlorhexidine gluconate 0.2% instead of normal saline or distilled water when flushing the suction system.

ClinicalTrials.gov, identifier NCT05206721.

The term bronchopneumonia describes an inflammation of the bronchioles centered in the lungs. A male patient, aged 77, complained of dyspnea for six months. The Modified Medical Research Council (mMRC) Dyspnea Scale showed grade 2 dyspnea, chest pain, cold, and fever for seven days. X-rays were done that revealed bronchopneumonia. The research aimed to understand the effect of chest physical therapy in patients admitted to high-density units. We, as physiotherapists, use a wide range of treatments, such as airway clearance procedures, early mobility, and active breathing exercises, all of which are useful in reducing the symptoms of pneumonia in this situation. The outcome measures used were the mMRC Dyspnea Scale, Intensive Care Unit (ICU) Mobility Scale, Functional Independence Measure (FIM), and Numerical Pain Rating Scale (NPRS). Early physiotherapy rehabilitation is beneficial in resolving bronchopneumonia and relieving dyspnea.

Acute pneumonia induced by Pseudomonas aeruginosa is characterized by massive infiltration of inflammatory cell and the production of reactive oxygen species (ROS), which lead to severe and transient pulmonary inflammation and acute lung injury. However, P.aeruginosa infection is resistant to multiple antibiotics and causes high mortality in clinic, the search for alternative prophylactic and therapeutic strategies is imperative.

This study was aimed to investigate the anti-inflammatory and antioxidant effects of DMB, a novel derivative of berberine, and explore the role of AIM2 inflammasome in P. aeruginosa-induced acute pneumonia.

Acute pneumonia mice were established by tracheal injection of P. aeruginosa suspension. Pathological changes of lung tissue were observed by its appearance and H&E staining. The lung coefficient ratio was measured to evaluate pulmonary edema. Inflammatory factors were detected by qRT-PCR, western blotting and immunohistochemistry. ROS and other indicators of oxidative damage were analyzed by flow cytometry and specific kit. Proteins related to AIM2 inflammasome were detected by western blotting.

Compared with the P. aeruginosa-induced group, DMB ameliorated pulmonary edema, hyperemia, and pathological damage based on its appearance and H&E staining in DMB groups. First, DMB attenuated the inflammatory response induced by P.aeruginosa. Compared with the P. aeruginosa-induced group, the lung coefficient ratio was decreased by 31.5%, the MPO activity of lung tissue was decreased by 44.0%, the mRNA expression levels of TNF-α, IL-1β and IL-6 were decreased by 64.8%, 51.2% and 64.0% respectively, and those protein expression levels were decreased by 40.1%, 42.8% and 47.8% respectively, and the number of white blood cells, neutrophils and monocytes were decreased by 53.5%, 29.4% and 13.7% in high dose (200 mg/kg) DMB group. Second, DMB alleviates oxidative stress in the lung tissue during P. aeruginosa-induced acute pneumonia. Compared with the P. aeruginosa-induced group, the level of GSH was increased by 42.5% and MDA was decreased by 49.5% in high dose DMB group. Moreover, the western blotting results showed that DMB markedly suppressed the expression of AIM2, ASC, Cleaved caspase1 and decreased the secretion of IL-1β. Additionally, these results were also confirmed by in vitro experiments using MH-S and BEAS-2B cell lines.

Taken together, these results indicated that DMB ameliorates P. aeruginosa-induced acute pneumonia through anti-inflammatory, antioxidant effects, and inhibition of AIM2 inflammasome activation.

Basic leucine zipper transcription factor ATF-like 2 (BATF2) is a transcription factor that is emerging as an important regulator of the innate immune system. BATF2 is among the top upregulated genes in human alveolar macrophages treated with LPS, but the signaling pathways that induce BATF2 expression in response to Gram-negative stimuli are incompletely understood. In addition, the role of BATF2 in the host response to pulmonary infection with a Gram-negative pathogen like Klebsiella pneumoniae (Kp) is not known. We show that induction of Batf2 gene expression in macrophages in response to Kp in vitro requires TRIF and type I interferon (IFN) signaling, but not MyD88 signaling. Analysis of the impact of BATF2 deficiency on macrophage effector functions in vitro showed that BATF2 does not directly impact macrophage phagocytic uptake and intracellular killing of Kp. However, BATF2 markedly enhanced macrophage proinflammatory gene expression and Kp-induced cytokine responses. In vivo, Batf2 gene expression was elevated in lung tissue of wild-type (WT) mice 24 h after pulmonary Kp infection, and Kp-infected BATF2-deficient (Batf2-/-) mice displayed an increase in bacterial burden in the lung, spleen, and liver compared with WT mice. WT and Batf2-/- mice showed similar recruitment of leukocytes following infection, but in line with in vitro observations, proinflammatory cytokine levels in the alveolar space were reduced in Batf2-/- mice. Altogether, these results suggest that BATF2 enhances proinflammatory cytokine responses in macrophages in response to Kp and contributes to the early host defense against pulmonary Kp infection.NEW & NOTEWORTHY This study investigates the signaling pathways that mediate induction of BATF2 expression downstream of TLR4 and also the impact of BATF2 on the host defense against pulmonary Kp infection. We demonstrate that Kp-induced upregulation of BATF2 in macrophages requires TRIF and type I IFN signaling. We also show that BATF2 enhances Kp-induced macrophage cytokine responses and that BATF2 contributes to the early host defense against pulmonary Kp infection.