Acinetobacter baumannii is an opportunistic pathogen causing several infections that are increasingly difficult to treat due to its ability to rapidly gain antibiotic resistances. These resistances can arise due to mutations through the activity of error-prone DNA polymerases, such as DNA polymerase V (DNA Pol V) in response to DNA damage. The regulation of the DNA damage response (DDR) in A. baumannii is not completely understood; the regulation of genes encoding multiple copies of DNA Pol V is not fully characterized. Through genome-wide mutagenesis, we have identified a novel TetR-like family regulator of the umuDC and umuC genes, which we have named Error-prone polymerase regulator (EppR). We have found that EppR represses the expression of the genes encoding DNA Pol V and itself through direct binding to an EppR motif in their promoters. Lastly, we show that EppR also regulates UmuDAb, previously identified as a regulator of genes encoding DNA Pol V. These two gene products are functionally required to ensure regulation of the expression of the two umuDC, the two umuC genes as well as the regulators umuDAb and eppR genes. With these results, we propose a model in which multiple transcription factors regulate the expression of all these genes.

Acinetobacter baumannii is a critical priority gram-negative bacterial species featured with multidrug resistance and biofilm formation. This study screened 46 indole derivative agents for their antimicrobial activities against clinical isolates of extensively drug-resistant A. baumannii (XDRAB) with various degrees of biofilm production. Three selected indole agents-5-iodoindole, 3-methylindole, and 7-hydroxyindole-were revealed to display potent antimicrobial and antibiofilm activity, including synergistic interplay with anti-A. baumannii antimicrobial drugs against XDRAB. Sub-inhibitory concentrations of these agents (particularly 7-hydroxyindole at 1/64 of MIC) not only inhibited XDRAB biofilm formation but also eradicated the mature biofilm. The survival rate of XDRAB-infected Galleria mellonella was improved with the treatment of 7-hydroxyindole. Mechanistically, 7-hydroxyindole was found to reduce the expression of quorum sensing/biofilm-implicated genes abaI and abaR. Together, the findings highlight the potential of indole derivatives against A. baumannii infections.

Extensively drug-resistant Acinetobacter baumannii (XDRAB) isolates pose a major public health threat to antimicrobial therapy and are highly prevalent in hospital settings. This study identified and characterized indole derivative agents for their antimicrobial and antibiofilm activities against XDRAB. Sub-inhibitory indole agents such as 7-hydroxyindole can both inhibit XDRAB biofilm formation and eradicate the mature biofilm. Indole agents warrant further investigation against hard-to-treat antimicrobial-resistant pathogens.

Acinetobacter baumannii (AB) is an opportunistic pathogen with growing clinical relevance due to its increasing level of antimicrobial resistance in the last few decades. In the event of an AB hospital outbreak, fast detection and localization of the pathogen is crucial, to prevent its further spread. However, contemporary diagnostic tools do not always meet the requirements for rapid and accurate diagnosis. For this reason, we report here the possibility of using gallium-68 labeled siderophores, bacterial iron chelators, for positron emission tomography imaging of AB infections. In our study, we radiolabeled several siderophores and tested their in vitro uptake in AB cultures. Based on the results and the in vitro properties of studied siderophores, we selected two of them for further in vivo testing in infectious models. Both selected siderophores, ferrioxamine E and ferrirubin, showed promising in vitro characteristics. In vivo, we observed rapid pharmacokinetics and no excessive accumulation in organs other than the excretory organs in normal mice. We demonstrated that the radiolabeled siderophores accumulate in AB-infected tissue in three animal models: a murine model of myositis, a murine model of dorsal wound infection and a rat model of pneumonia. These results suggest that both siderophores radiolabeled with Ga-68 could be used for PET imaging of AB infection.

Decades of antibiotic misuse have accelerated the emergence of multi- and extensively drug-resistant bacteria. Bacterial pathogens employ several strategies such as antibiotic resistance, tolerance, and biofilm formation in response to extreme environments and antibiotic stress. Another crucial survival mechanism involves the stochastic generation of bacterial subpopulations known as persisters, which can endure high concentrations of antibiotics. Upon removal of antibiotic stress, these subpopulations revert back to their original phenotype which links them to the relapse and recalcitrance of chronic infections, a significant problem in clinical settings. Persistent infections are particularly notable in Acinetobacter baumannii, a top-priority ESKAPE pathogen, where carbapenems serve as last-resort antibiotics. Several reports indicate the rising therapeutic failure of carbapenems due to persistence, underscoring the importance of developing anti-persister therapeutics. In this study, we explored the mechanisms of transient persister formation in A. baumannii against meropenem. Our investigation revealed significant changes in membrane properties and energetics in meropenem persisters of A. baumannii, including a noteworthy increase in tolerance to other antibiotics. This understanding guided the evaluation of an in-house collection of GRAS status compounds for their potential anti-persister activity. The compound thymol demonstrated remarkable inhibitory activity against meropenem persisters of A. baumannii and other ESKAPE pathogens. Further investigation revealed its impact on persister cell physiology, including efflux pump inhibition and disruption of cellular respiration. Given our results, we propose a compelling strategy where thymol could be employed either as a monotherapy or in combination with meropenem in anti-persister therapeutics.

With the global rise of antimicrobial resistance, phage therapy is increasingly re-gaining traction as a strategy to treat bacterial infections. For phage therapy to be successful however, we first need to isolate appropriate candidate phages for both clinical and experimental research. Acinetobacter baumannii is an opportunistic pathogen known for its ability to rapidly evolve resistance to antibiotics, making it a prime target for phage therapy. Yet phage isolation may be hampered by A. baumannii's ability to rapidly switch between capsular states. Here, we report the discovery and structural characterisation of a novel lytic phage, Mystique. This phage was initially isolated against the wild-type AB5075: a commonly used clinical model strain. When screening Mystique on 103 highly diverse isolates of A. baumannii, we found that it has a broad host range, being able to infect 85.4% of all tested strains when tested on bacterial lawns - a host range that expanded to 91.3% when tested in liquid culture. This variation between solid and liquid culturing conditions on phage infectivity was also observed for several other phages in our collection that were assumed unable to infect AB5075, and some capsule negative mutants that seemed resistant to Mystique proved susceptible when assayed in liquid. This highlights how differences in culturing conditions can drastically impact phage infectivity, with important consequences for phage isolation and characterisation efforts. Finally, Mystique was found to be able to infect other species of Acinetobacter, making it a multi-species phage with broad applicability for further research.

The rise in aesthetic surgery in recent years has led to an increased incidence of complications associated with these procedures. Liposuction and autologous fat transfer have become some of the most common cosmetic interventions worldwide, also raising the risk of developing postoperative infections, including those caused by multidrug-resistant Gram-negative bacilli, which can be life-threatening. We present the case of a 40-year-old woman who developed septic shock secondary to deep necrotizing fasciitis in the right thigh following liposuction and autologous fat transfer to the buttocks. During the postoperative period, she developed a necrotizing soft tissue infection affecting the right thigh and buttock, which progressed to necrotizing fasciitis. The patient required surgical debridement, fasciotomy, and combined antibiotic therapy. Tissue cultures revealed multidrug-resistant Acinetobacter baumannii complex haemolyticus, sensitive to carbapenems. The patient had surgical debridement and a 14-day course of antibiotics, resulting in clinical recovery. A. baumannii is a significant cause of nosocomial infections worldwide, and its persistence on inanimate surfaces may be underestimated. Complications such as necrotizing soft tissue infections are typically caused by Gram-positive microorganisms such as methicillin-resistant Staphylococcus aureus and Gram-negative fermenting enterobacteria. The isolation of A. baumannii in soft tissue cultures is unusual, making this case notable, as necrotizing soft tissue infections caused by this nonfermenting Gram-negative bacillus have not been previously reported following aesthetic body contouring surgery.

Acinetobacter baumannii is an obligately aerobic, non-motile, non-fermenting, gram-negative, opportunistic pathogen. The fact that this pathogen, which is the leading cause of nosocomial infections, is naturally resistant to many antibiotics and quickly acquires new resistance mechanisms gradually limits the antibiotic options that can be used in treatment. So, our study aims to investigate the in vitro antibacterial effects of eravacycline, a new tetracycline-class antibiotic, and compare this antibiotic with the antibiotics used in the clinic to treat the infection caused by A. baumannii. Also, eravacycline was tested in combination with meropenem or colistin against A. baumannii strains, which are resistant to colistin and meropenem. The antibiotic susceptibility of strains was determined by the microbroth dilution method. In addition, the agar dilution method determined the mutant inhibition concentration (MPC) values of the studied antibiotics. To investigate the effects of the antibiotics mentioned in our study on biofilm formation, the biofilm-forming abilities of the strains were evaluated by the crystal violet staining method. The bactericidal and synergistic effects of the studied antibiotics alone or in combination were determined by the time-dependent killing curve (TKC) method.

The present antibacterial susceptibility experiments showed that 98% of the strains were multi-drug resistant (MDR). Our results in mutant inhibition studies showed that eravacycline is an antibiotic with the potential to prevent the emergence of resistant mutants with its low MPC value. When the effects of antibiotics on biofilm formation were investigated in our thesis study, it was determined that 95% of our strains formed biofilm. In biofilm inhibition experiments, it was observed that eravacycline at minimum inhibitory concentration (MIC) inhibited biofilm formation by 84% alone, 86% combined with colistin, and 85% combined with meropenem. Our combination experiments showed that 1×MIC eravacycline-meropenem and 4×MIC eravacycline-colistin combinations were synergistic against A. baumannii strains. In addition, the combination of 4×MIC eravacycline-meropenem also showed bactericidal activity at the 24th hour. No antagonist effects were detected in our combination studies.

Present results reveal essential pharmacodynamic data on eravacycline, a new antibiotic for treating A. baumannii infections, which poses a global threat.

Not applicable.

Vertebral osteomyelitis (VO) is a major cause of condemnation in swine slaughterhouses, leading to economic losses for farmers. This study aimed to investigate the characteristics and classification of VO cases in South Korean slaughterhouses, focusing on their relationship with pyemia and their potential to reduce unnecessary total condemnation.

Our findings confirmed that swine VOs are often associated with tail-biting injuries, particularly in the posterior vertebrae, underscoring tail biting as a prominent risk factor. Trueperella pyogenes were the most prevalent among the bacterial pathogens, while additional less common bacteria were also identified, warranting further research on their potential pathogenic roles. According to the VO classification scheme used in this study, 75% of the 20 VO cases examined were classified as acute VO, whereas the remaining cases were chronic. It was revealed that only 10% (2/20) of the VO cases were in a state of pyemia at the time of slaughter (true pyemia) and these true pyemia cases were found only in the acute VOs.

The VO classification scheme tested in this study demonstrated high sensitivity (100%), indicating its robustness in avoiding false negatives and ensuring food safety. Of the carcasses that could have undergone unnecessary condemnation, 22.2% were excluded. The results indicate that the VO classification scheme is recommended as a measure to reduce unnecessary total condemnation induced by VO.

Catheter-related bloodstream infections (CRBSIs) are serious complications in patients requiring long-term intravascular catheterization, particularly in immunocompromised individuals. Acinetobacter lwoffii, a low-virulence, non-fermentative gram-negative bacillus, is an uncommon cause of CRBSI. We report the case of a 43-year-old female patient on long-term hemodialysis who developed A. lwoffii-associated CRBSI. This case highlights the diagnostic challenges, management strategies, and importance of early intervention in infections caused by A. lwoffii.

In recent years, the research community has been interested in members of the Acinetobacter genus mainly because of their role as causative agents of nosocomial infections. However, this rich-in-species genus has been proven to play a significant role in several biotechnological processes, such as bioremediation and fermented foods production. To partially fill the lack of information on Acinetobacter's dualistic nature, in this review, based on literature data, we attempt to summarize the available information on the different roles the members of the genus play by considering their genetic constitution and metabolic properties. We analyzed reports of genetic divergence between the pathogenic and non-pathogenic species and isolates, which can be explained by their high adaptability to the different ecological niches. In turn, this adaptability could result from intrinsic genetic variability due to mechanisms of horizontal genetic transfer, as well as high mutability determined by the expression of error-prone DNA polymerases. Yet, we concluded that further studies are needed, especially whole-genome sequencing of non-pathogenic isolates, which for the moment are relatively scarce.

Type VI secretion system (T6SS) is utilized by many Gram-negative bacteria to eliminate competing bacterial species and manipulate host cells. Acinetobacter baumannii ATCC 17978 utilizes T6SS at the expense of losing pAB3 plasmid to induce contact-dependent killing of competitor microbes, resulting in the loss of antibiotic resistance carried by pAB3. However, the regulatory network associated with T6SS in A. baumannii remains poorly understood. Here, we identified an Mn2+-dependent post-transcriptional regulation of T6SS mediated by a bonafide small RNA, AbsR28. A. baumannii utilizes MumT, an Mn2+-uptake inner membrane transporter, for the uptake of extracellular Mn2+ during oxidative stress. We demonstrate that the abundance of intracellular Mn2+ enables complementary base pairing of AbsR28-tssM mRNA (that translates to TssM, one of the vital inner membrane components of T6SS), inducing RNase E-mediated degradation of tssM mRNA and resulting in T6SS repression. Thus, AbsR28 mediates a crosstalk between MumT and T6SS in A. baumannii.IMPORTANCESmall RNAs (sRNAs) are identified as critical components within the bacterial regulatory networks involved in fine regulation of virulence-associated factors. The sRNA-mediated regulation of type VI secretion system (T6SS) in Acinetobacter baumannii was unchartered. Previously, it was demonstrated that A. baumannii ATCC 17978 cells switch from T6- to T6+ phenotype, resulting in the loss of antibiotic resistance conferred by plasmid pAB3. Furthermore, the derivatives of pAB3 found in recent clinical isolates of A. baumannii harbor expanded antibiotic resistance genes and multiple determinants for virulence factors. Hence, the loss of this plasmid for T6SS activity renders A. baumannii T6+ cells susceptible to antibiotics and compromises their virulence. Our findings show how A. baumannii tends to inactivate T6SS through an sRNA-mediated regulation that relies on Mn2+ and retains pAB3 during infection to retain antibiotic resistance genes carried on the plasmid.

Noncoding small RNAs are essential for modulating bacterial gene expression, especially under carbon and nutrient-limited conditions. In this study, by using both in silico and molecular hybridization tools, we identified a carbon source responsive small RNA in Acinetobacter baumannii DS002. Expression of corresponding gene, abcR200, located at the intergenic region of omt (O-methyl transferase) and orf72 genes, is under the transcriptional control of a global transcriptional factor, leucine responsive regulatory protein (Lrp). A sequence motif that serves as a target for Lrp was found overlapping the abcR200 promoter (PabcR200). Chromatin immunoprecipitation demonstrated that Lrp oligomers, formed under low leucine conditions, strongly interacted to the PabcR200. However, the observed interactions were disrupted in the presence of leucine, as leucine promoted dissociation of Lrp to monomers and dimers, the conformation unfavorable to interact with PabcR200. The abcR200 promoter activity increased with increase of exogenous leucine concentrations, and at 2 mM leucine concentration, maximum promoter activity was observed. The AbcR200 target mRNAs were identified by analyzing the transcriptome of abcR200 negative strain of A. baumannii. Intriguingly, in abcR200 negative background, expression of lut (lactate utilization) mRNA has increased, suggesting lut mRNA as one of the mRNA targets for AbcR200. Consistent of this observation, there existed extensive sequence complementarity between AbcR200 and lut mRNA, especially in the regions coding LutP, LutE, and LutR. In support of the observed sequence complementarity, the levels of lut mRNA encoded proteins got elevated in abcR200 negative HS002 strains suggesting a role for AbcR200 in translational inhibition of lut mRNA.

Background/Objectives:Acinetobacter baumannii is a highly multidrug-resistant pathogen resistant to almost all classes of antibiotics; new therapeutic strategies against this infectious agent are urgently needed. Shikimate kinase is an enzyme belonging to the shikimate pathway and has become a potential target for drug development. This work describes the search for Food and Drug Administration (FDA)-approved drugs and natural compounds, including gallic acid, that could be repurposed as selective shikimate kinase inhibitors by integrated computational and experimental approaches. Methods: Approaches to drug design using structure-based and ligand-based methodology, in-silico screening, molecular docking, and molecular dynamics for the study of both binding affinity and stability. Experimental Validation Determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on Acinetobacter baumannii and Enterococcus faecalis. Results/Conclusions: Among them, gallic acid, obtained from plants, proved to be the most promising compound that showed sufficient binding with shikimate kinase through computational studies. Gallic acid showed very good activity against Acinetobacter baumannii and Enterococcus faecalis in the MIC and MBC assay, respectively. Gallic acid exhibited better activity against Acinetobacter baumannii due to the overexpression of shikimate kinase. Gallic acid has emerged as a potential therapeutic candidate drug against A. baumannii infection and, therefore, as a strategy against the appearance of multidrug-resistant microorganisms. This study not only identifies a novel repurposing opportunity for gallic acid but also provides a comprehensive computational and experimental framework for accelerating antimicrobial drug discovery against multidrug-resistant pathogens.

Direct reuse of biogas residue (BR) has the potential to contribute to the dissemination of antibiotic resistance genes (ARGs). Although high-temperature composting has been demonstrated as an effective method for the harmless treatment of organic waste, there is few researches on the fate of ARGs in high-temperature composting of BR. This research examined the impact of adding 5% chitosan and 15% peat on physicochemical characteristics, microbial communities, and removal of ARGs during BR-straw composting in 12 Biolan 220L composters for 48 days. Our results showed that the simultaneous addition of chitosan and peat extended the high-temperature period, and increased the highest temperature to 74 °C and germination index. These effects could be attributed to the presence of thermophilic cellulose-decomposing genera (Thermomyces and Thermobifida). Although the microbial communities differed compositionally among temperature stages, their dissimilarity drastically reduced at final stage, indicating that the impact of different treatments on microbial community composition decreases at the end of composting. Peat had a greater impact on aerobic genera capable of cellulose degradation at thermophilic stage than chitosan. Surprisingly, despite the total copy number of ARGs significantly decreased during composting, especially in the treatment with both chitosan and peat, intl1 gene abundance significantly increased 2 logs at thermophilic stage and maintained high level in the final compost, suggesting there is still a potential risk of transmission and proliferation of ARGs. Our work shed some lights on the development of waste resource utilization and emerging contaminants removal technology.

Gut microorganism (GM) is an integral component of the host microbiome and health system. Abuse of antibiotics disrupts the equilibrium of the microbiome, affecting environmental pathogens and host-associated bacteria alike. However, relatively little research on Bacillus licheniformis alleviates the adverse effects of antibiotics. To test the effect of B. licheniformis as a probiotic supplement against the effects of antibiotics, cefalexin was applied, and the recovery from cefalexin-induced jejunal community disorder and intestinal barrier damage was investigated by pathology, real-time PCR (RT-PCR), and high-throughput sequencing (HTS). The result showed that A group (antibiotic treatment) significantly reduced body weight and decreased the length of jejunal intestinal villi and the villi to crypt (V/C) value, which also caused structural damage to the jejunal mucosa. Meanwhile, antibiotic treatment suppressed the mRNA expression of tight junction proteins ZO-1, claudin, occludin, and Ki67 and elevated MUC2 expression more than the other Groups (P < 0.05 and P < 0.01). However, T group (B. licheniformis supplements after antibiotic treatment) restored the expression of the above genes, and there was no statistically significant difference compared to the control group (P > 0.05). Moreover, the antibiotic treatment increased the relative abundance of 4 bacterial phyla affiliated with 16 bacterial genera in the jejunum community, including the dominant Firmicutes, Proteobacteria, and Cyanobacteria in the jejunum. B. licheniformis supplements after antibiotic treatment reduced the relative abundance of Bacteroidetes and Proteobacteria and increased the relative abundance of Firmicutes, Epsilonbacteraeota, Lactobacillus, and Candidatus Stoquefichus. This study uses mimic real-world exposure scenarios by considering the concentration and duration of exposure relevant to environmental antibiotic contamination levels. We described the post-antibiotic treatment with B. licheniformis could restore intestinal microbiome disorders and repair the intestinal barrier. KEY POINTS: • B. licheniformis post-antibiotics restore gut balance, repair barrier, and aid health • Antibiotics harm the gut barrier, alter structure, and raise disease risk • Long-term antibiotics affect the gut and increase disease susceptibility.

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a persistent nosocomial pathogen that poses a significant threat to global public health, particularly in intensive care units (ICUs). Here we report a three-month longitudinal genomic surveillance study conducted in a Hangzhou ICU in 2021. This followed a three-month study conducted in the same ICU in 2019, and infection prevention and control (IPC) interventions targeting patients, staff and the ICU environment. Most A. baumannii isolated in this ICU in 2021 were CRAB (80.9%; 419/518) with higher-level resistance to carbapenems. This was accompanied by the proportion of global clone 2 (GC2) isolates falling from 99.5% in 2019 to 50.8% (213/419) in 2021. The phylogenetic diversity of GC2 increased, apparently driven by regular introductions of distinct clusters in association with patients. The remaining CRAB (40.2%; 206/419) were a highly clonal population of ST164. Isolates of ST164 carried blaNDM-1 and blaOXA-23 carbapenemase genes, and exhibited higher carbapenem MIC50/MIC90 values than GC2. Comparative analysis of publicly available genomes from 26 countries (five continents) revealed that ST164 has evolved towards carbapenem resistance on multiple independent occasions. Its success in this ICU and global capacity for acquiring resistance determinants indicate that ST164 CRAB is an emerging high-risk lineage of global concern.

A straightforward synthesis of the pentasaccharide with a readily available linker arm corresponding to the O-antigenic polysaccharide of Acinetobacter junii strain 65 has been achieved in good yield. The synthesis has been carried out using thioglycosides as glycosyl donor in the presence of a combination of N-iodosuccinimide (NIS) and trifluoromethanesulfonic acid (TfOH) as thiophilic activator. The yields of the glycosylation steps were very good with satisfactory stereochemistry at the glycosidic linkages. The pentasaccharide derivative has also been obtained using a one-pot iterative glycosylation strategy.

Non-human primate (NHPs) conservation sites could be sites of exchange of pathogens involved in infectious diseases. It is important to assess the potential risks associated with this type of structure. The objective of this study was to carry out a risk assessment of the Primatology Centre housed in the Interdisciplinary Centre for Medical Research of Franceville (CIRMF).

A questionnaire was administered to the centre's staff to assess the risk associated with each workstation, followed by a review of the various pathogens identified in NHPs. The data were analysed using two diagrams: the Kiviat diagram and the Pareto diagram.

Based on our results, a variety of pathogens such as viruses, bacteria and parasites, potentially transmissible to humans, were described in the NHPs at the Primatology Centre of CIRMF. The position most exposed to zoonotic risks was that of animal handlers.

The Primatology Centre of CIRMF is a potential transfer site for the transfer of zoonotic agents. To avoid the risk of parasite exchange between staff and animals, the implementation of biosecurity measures is essential.

Acinetobacter baumannii is a globally distributed opportunistic pathogen in human health settings, including in intensive care units (ICUs). We investigated the contamination of a French small animal ICU with A. baumannii. We discovered repeated animal contamination by A. baumannii, and phylogenetic analysis traced contamination back to a potential foreign animal origin. Genomic analysis combined with antibiotic susceptibility testing revealed heteroresistance to penicillin and aminoglycoside mediated by insertion sequence dynamics and also suggest a potential cross-resistance to human-restricted piperacillin-tazobactam combination. The A. baumannii isolates of the animal ICU belong to the International Clone 2 commonly found in human health settings. Our results suggest a high adaptation of this lineage to healthcare settings and provide questions on the requirements for genetic determinants enabling adaptation to host and abiotic conditions.

Acinetobacter baumannii (A. baumannii) is an widespread pathogen and carbapenem-resistant strains are great threat to hospitalized patients. This study is aimed to investigate the clinical characteristics, antimicrobial resistance patterns, and risk factors associated with carbapenem resistance in nosocomial, healthcare-associated (HCA), and community-acquired (CA) A. baumannii infections.

This study retrospectively reviewed cases in a tertiary hospital in southern China between January 1, 2019, and December 31, 2021. Univariate and multivariate logistic regression analyses were performed to identified the risk factors of carbapenem resistance in nosocomial, HCA and CA A. baumannii infections.

A total of 391 patients with A. baumannii infection were included. Of these patients, 96 (24.6%) had nosocomial infections, 215 (55.0%) had HCA infections, and 80 (20.5%) had CA infections. The overall 30-day mortality rates of nosocomial and HCA infection patients was significantly higher than that of CA infection (P<0.05). The incidence of antimicrobial resistance was also higher in nosocomial and HCA bacteremia than that in CA bacteremia (P<0.05). Logistic regression analysis identified age ≥60 years, urethral catheterization, and exposure to two or more antibiotics as the independent risk factors for carbapenem-resistant A. baumannii (CRAB) infection in the nosocomial infection group and exposure to two or more antibiotics and endotracheal intubation in the HCA infection group. However, malignant tumors and hematological diseases were identified as protective factors against CRAB infection in the HCA group.

These data suggest that HCA A. baumannii infection is quite different from CA infection, with antimicrobial resistance and 30-day mortality rates similar to those of nosocomial infections. Additionally, the risk factors for CRAB development in the CA, HCA, and nosocomial groups were not the same, which may provides the help for controlling practices and instruction empirical clinical medication.

One effective method to combat bacterial infections is by using bacteria itself as a weapon. Lactobacillus is a type of fermenting bacterium that has probiotic properties and has demonstrated antimicrobial benefits against other bacteria. Cyclodipeptides (CDPs), present in the supernatant of Lactobacillus, possess several antimicrobial properties.

In this study, the CDP fraction was isolated from the supernatant of Lactobacillus plantarum (L. plantarum). This fraction was then loaded onto graphene oxide nanosheets (GO NSs). The study assessed the substance's ability to inhibit bacterial growth by using the minimum inhibitory concentration (MIC) method on A. baumannii and S. aureus strains that were obtained from clinical samples. To determine the substance's impact on biofilm formation, the microtiter plate method was used. Moreover, the checkerboard technique was employed to explore the potential synergistic effects of these two substances.

According to the study, the minimum inhibitory concentration (MIC) of the desired compound was found to be 1.25 mg/mL against S. aureus and 2.5 mg/mL against A. baumannii. Furthermore, at a concentration of 10 mg/mL, the compound prevented 81.6% (p < 0.01) of biofilm production in A. baumannii, while at a concentration of 1.25 mg/mL, it prevented 47.5% (p < 0.05) of biofilm production in S. aureus. The study also explored the synergistic properties of two compounds using the checkerboard method.

In general, we found that GO NSs possess antimicrobial properties and enhance cyclodipeptides' activity against S. aureus and A. baumannii.

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious worldwide medical problem. This study was designed to clarify the genetic and epidemiological properties of MDR A. baumannii clinical isolates.

A total of 66 MDR A. baumannii isolates were obtained from 66 inpatients between May 2019 and February 2020 in a university hospital in Nepal. Whole genomes of these isolates were sequenced using next-generation sequencing. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence typing (MLST) and clonal complex (CC) analysis were conducted, and drug-resistance genes were identified.

Of the 66 isolates, 26 harboured a gene encoding NDM-type metallo-β-lactamase, and 55 harboured a gene encoding the 16S rRNA methyltransferase, ArmA. All isolates had point mutations in the quinolone-resistance-determining regions of gyrA and parC. Phylogenetic analysis showed that 55 isolates harboured armA, 26 harboured blaNDM-1, and14 harboured blaPER-7. Multilocus sequence typing and CC analysis revealed that 34 isolates belonged to CC2 (ST2), 10 to CC1 (nine ST1 and one ST623), and eight to CC149 (ST149). Compared to our previous study on MDR A. baumannii in Nepal in 2012, the isolation rate of CC2 increased, whereas that of CC149 decreased between 2012 and 2020.

This study indicates that MDR A. baumannii producing carbapenemase and 16S rRNA methyltransferase, with high resistance to carbapenems and/or aminoglycosides, are spreading in medical settings in Nepal. The genetic backgrounds of MDR A. baumannii isolates have shifted to international clone 2 over several years.

Bile acids (BAs) play a crucial role in the human body's defense against infections caused by bacteria, fungi, and viruses. BAs counteract infections not only through interactions with intestinal bacteria exhibiting bile salt hydrolase (BSH) activity but they also directly combat infections. Building upon our research group's previous discoveries highlighting the role of BAs in combating infections, we have initiated an in-depth investigation into the interactions between BAs and intestinal microbiota. Leveraging the existing literature, we offer a comprehensive analysis of the relationships between BAs and 16 key microbiota. This investigation encompasses bacteria (e.g., Clostridioides difficile (C. difficile), Staphylococcus aureus (S. aureus), Escherichia coli, Enterococcus, Pseudomonas aeruginosa, Mycobacterium tuberculosis (M. tuberculosis), Bacteroides, Clostridium scindens (C. scindens), Streptococcus thermophilus, Clostridium butyricum (C. butyricum), and lactic acid bacteria), fungi (e.g., Candida albicans (C. albicans) and Saccharomyces boulardii), and viruses (e.g., coronavirus SARS-CoV-2, influenza virus, and norovirus). Our research found that Bacteroides, C. scindens, Streptococcus thermophilus, Saccharomyces boulardii, C. butyricum, and lactic acid bacteria can regulate the metabolism and function of BSHs and 7α-dehydroxylase. BSHs and 7α-dehydroxylase play crucial roles in the conversion of primary bile acid (PBA) to secondary bile acid (SBA). It is important to note that PBAs generally promote infections, while SBAs often exhibit distinct anti-infection roles. In the antimicrobial action of BAs, SBAs demonstrate antagonistic properties against a wide range of microbiota, with the exception of norovirus. Given the intricate interplay between BAs and intestinal microbiota, and their regulatory effects on infections, we assert that BAs hold significant potential as a novel approach for preventing and treating microbial infections.

Nasal colonization of two preterm infants in our neonatal ICU by Acinetobacter junii carrying the blaOXA-58 carbapenem resistance gene was demonstrated.

To study whether the two isolates were identical and to investigate the hypotheses of cross-transmission.

Antibiotic susceptibility tests of the two isolates were performed by standard diffusion and the MICs of carbapenems determined by the MIC-gradient strip method. The blaOXA-58 gene was detected by PCR. Isolates were compared using SNP analysis performed after WGS. The timelines of the two cases were determined based on the investigations and the study of the patients' records.

The two isolates corresponded to the same strain, with case 1 being the index case, demonstrating cross-transmission to case 2.

Acquisition of the strain was likely due to the recent carbapenem treatment of case 1 and cross-transmission due to the high amount of care administered to the two preterm infants. This is the first description of cross-transmission of A. junii carrying the blaOXA-58 gene.

Acinetobacter baumannii is observed as a common species of Gram-negative bacteria that exist in soil and water. Despite being accepted as a typical component of human skin flora, it has become an important opportunistic pathogen, especially in healthcare settings. The pathogenicity of A. baumannii is attributed to its virulence factors, which include adhesins, pili, lipopolysaccharides, outer membrane proteins, iron uptake systems, autotransporter, secretion systems, phospholipases etc. These elements provide the bacterium the ability to cling to and penetrate host cells, get past the host immune system, and destroy tissue. Its infection is a major contributor to human pathophysiological conditions including pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. It is challenging to treat infections brought on by this pathogen since this bacterium has evolved to withstand numerous drugs and further emergence of drug-resistant A. baumannii results in higher rates of morbidity and mortality. The long-term survival of this bacterium on surfaces of medical supplies and hospital furniture facilitates its frequent spread in humans from one habitat to another. There is a need for urgent investigations to find effective drug targets for A. baumannii as well as designing novel drugs to reduce the survival and spread of infection. In the current review, we represent the specific features, pathogenesis, and molecular intricacies of crucial drug targets of A. baumannii. This would also assist in proposing strategies and alternative therapies for the prevention and treatment of A. baumannii infections and their spread.

Acinetobacter lwoffii (A. lwoffii) is a Gram-negative bacteria common in the environment, and it is the normal flora in human respiratory and digestive tracts. The bacteria is a zoonotic and opportunistic pathogen that causes various infections, including nosocomial infections. The aim of this study was to identify A. lwoffii strains isolated from bovine milk with subclinical mastitis in China and get a better understanding of its antimicrobial susceptibility and resistance profile. This is the first study to analyze the drug resistance spectrum and corresponding mechanisms of A. lwoffii isolated in raw milk.

Four A. lwoffii strains were isolated by PCR method. Genetic evolution analysis using the neighbor-joining method showed that the four strains had a high homology with Acinetobacter lwoffii. The strains were resistant to several antibiotics and carried 17 drug-resistance genes across them. Specifically, among 23 antibiotics, the strains were completely susceptible to 6 antibiotics, including doxycycline, erythromycin, polymyxin, clindamycin, imipenem, and meropenem. In addition, the strains showed variable resistance patterns. A total of 17 resistance genes, including plasmid-mediated resistance genes, were detected across the four strains. These genes mediated resistance to 5 classes of antimicrobials, including beta-lactam, aminoglycosides, fluoroquinolones, tetracycline, sulfonamides, and chloramphenicol.

These findings indicated that multi-drug resistant Acinetobacter lwoffii strains exist in raw milk of bovine with subclinical mastitis. Acinetobacter lwoffii are widespread in natural environmental samples, including water, soil, bathtub, soap box, skin, pharynx, conjunctiva, saliva, gastrointestinal tract, and vaginal secretions. The strains carry resistance genes in mobile genetic elements to enhance the spread of these genes. Therefore, more attention should be paid to epidemiological surveillance and drug resistant A. lwoffii.

Ammonium polyphosphate (APP), a pivotal constituent within environmentally friendly flame retardants, exhibits notable decomposition susceptibility and potentially engenders ecological peril. Consequently, monitoring the APP concentration to ensure product integrity and facilitate the efficacious management of wastewater from production processes is of great significance. A fluorescent assay was devised to swiftly discern APP utilizing 4',6'-diamino-2-phenylindole (DAPI). With increasing APP concentrations, DAPI undergoes intercalation within its structure, emitting pronounced fluorescence. Notably, the flame retardant JLS-PNA220-A, predominantly comprising APP, was employed as the test substrate. Establishing a linear relationship between fluorescence intensity (F-F0) and JLS-PNA220-A concentration yielded the equation y = 76.08x + 463.2 (R2 = 0.9992), with a LOD determined to be 0.853 mg/L. The method was used to assess the degradation capacity of APP-degrading bacteria. Strain D-3 was isolated, and subsequent analysis of its 16S DNA sequence classified it as belonging to the Acinetobacter genus. Acinetobacter nosocomialis D-3 demonstrated superior APP degradation capabilities under pH 7 at 37 °C, with degradation rates exceeding 85% over a four-day cultivation period. It underscores the sensitivity and efficacy of the proposed method for APP detection. Furthermore, Acinetobacter nosocomialis D-3 exhibits promising potential for remediation of residual APP through environmental biodegradation processes.

Multidrug-resistant (MDR) bacteria of the utmost importance are extended-spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. (VRE). In this study, an evaluation of MDR bacteria in surgical intensive care units in a tertiary referral hospital was conducted. The study aimed to characterize β-lactamases and other resistance traits of Gram-negative bacteria isolated in surgical intensive care units (ICUs). Disk diffusion and the broth dilution method were used for antibiotic susceptibility testing, whereas ESBL screening was performed through a double disk synergy test and an inhibitor-based test with clavulanic acid. A total of 119 MDR bacterial isolates were analysed. ESBL production was observed in half of the Proteus mirabilis, 90% of the Klebsiella pneumoniae and all of the Enterobacter cloacae and Escherichia coli isolates. OXA-48 carbapenemase, carried by the L plasmid, was detected in 34 K. pneumoniae and one E. coli and Enterobacter cloacae complex isolates, whereas NDM occurred sporadically and was identified in three K. pneumoniae isolates. OXA-48 positive isolates coharboured ESBLs belonging to the CTX-M family in all but one isolate. OXA-23 carbapenemase was confirmed in all A. baumannii isolates. The findings of this study provide valuable insight of resistance determinants of Enterobacterales and A. baumannii which will enhance surveillance and intervention strategies that are necessary to curb the ever-growing carbapenem resistance rates.

Acinetobacter baumannii has become a prominent nosocomial pathogen, primarily owing to its remarkable ability to rapidly acquire resistance to a wide range of antimicrobial agents and its ability to persist in diverse environments. However, there is a lack of data on the molecular epidemiology and its potential implications for public health of A. baumannii strains exhibiting clinically significant resistances that originate from non-clinical environments. Therefore, the genetic characteristics and resistance mechanisms of 80 A. baumannii-calcoaceticus (ABC) complex isolates, sourced from environments associated with poultry and pig production, municipal wastewater treatment plants (WWTPs), and clinical settings, were investigated. In total, our study classified 54 isolates into 29 previously described sequence types (STs), while 26 isolates exhibited as-yet-unassigned STs. We identified a broad range of A. baumannii STs originating from poultry and pig production environments (e.g., ST10, ST238, ST240, ST267, ST345, ST370, ST372, ST1112 according to Pasteur scheme). These STs have also been documented in clinical settings worldwide, highlighting their clinical significance. These findings also raise concerns about the potential zoonotic transmission of certain STs associated with livestock environments. Furthermore, we observed that clinical isolates exhibited the highest diversity of antimicrobial resistance genes (ARGs). In contrast to non-clinical isolates, clinical isolates typically carried a significantly higher number of ARGs, ranging from 10 to 15. They were also the exclusive carriers of biocide resistance genes and acquired carbapenemases (blaOXA-23, blaOXA-58, blaOXA-72, blaGIM-1, blaNDM-1). Additionally, we observed that clinical strains displayed an increased capacity for carrying plasmids and undergoing genetic transformation. This heightened capability could be linked to the intense selective pressures commonly found within clinical settings. Our study provides comprehensive insights into essential aspects of ABC isolates originating from livestock-associated environments and clinical settings. We explored their resistance mechanisms and potential implications for public health, providing valuable knowledge for addressing these critical issues.

Acinetobacter baumannii is a major cause of nosocomial infections, and its highly adaptive nature and broad range of antibiotic resistance enable it to persist in hospital environments. A. baumannii often employs two-component systems (TCSs) to regulate adaptive responses and virulence-related traits. This study describes a previously uncharacterized TCS in the A. baumannii ATCC19606 strain, consisting of a transcriptional sensor, DJ41_1407, and its regulator, DJ41_1408, located adjacent to GacA of the GacSA TCS. Markerless mutagenesis was performed to construct DJ41_1407 and DJ41_1408 single and double mutants. DJ41_1408 was found to upregulate 49 genes and downregulate 43 genes, most of which were associated with carbon metabolism and other metabolic pathways, such as benzoate degradation. MEME analysis revealed a putative binding box for DJ41_1408, 5'TGTAAATRATTAYCAWTWAT3'. Colony size, motility, biofilm-forming ability, virulence, and antibiotic resistance of DJ41_1407 and DJ41_1408 single and double mutant strains were assessed against wild type. DJ41_1407 was found to enhance motility, while DJ41_1408 was found to upregulate biofilm-forming ability, and may also modulate antibiotic response. Both DJ41_1407 and DJ41_1408 suppressed virulence, based on results from a G. mellonella infection assay. These results showcase a novel A. baumannii TCS involved in metabolism, with effects on motility, biofilm-forming ability, virulence, and antibiotic response.

Acinetobacter pneumonia is a significant healthcare-associated infection that poses a considerable challenge to clinicians due to its multidrug-resistant nature. Recent world events, such as the COVID-19 pandemic, have highlighted the need for effective treatment and management strategies for Acinetobacter pneumonia. In this review, we discuss lessons learned from recent world events, particularly the COVID-19 pandemic, in the context of the treatment and management of Acinetobacter pneumonia. We performed an extensive literature review to uncover studies and information pertinent to the topic. The COVID-19 pandemic underscored the importance of infection control measures in healthcare settings, including proper hand hygiene, isolation protocols, and personal protective equipment use, to prevent the spread of multidrug-resistant pathogens like Acinetobacter. Additionally, the pandemic highlighted the crucial role of antimicrobial stewardship programs in optimizing antibiotic use and curbing the emergence of resistance. Advances in diagnostic techniques, such as rapid molecular testing, have also proven valuable in identifying Acinetobacter infections promptly. Furthermore, due to the limited availability of antibiotics for treating infections caused A. baumannii, alternative strategies are needed like the use of antimicrobial peptides, bacteriophages and their enzymes, nanoparticles, photodynamic and chelate therapy. Recent world events, particularly the COVID-19 pandemic, have provided valuable insights into the treatment and management of Acinetobacter pneumonia. These lessons emphasize the significance of infection control, antimicrobial stewardship, and early diagnostics in combating this challenging infection.

This study investigated the genetic diversity, antimicrobial resistance profiles, and virulence characteristics of Acinetobacter non-baumannii isolates obtained from four hospitals in southern Thailand. Clinical data, genome information, and average nucleotide identity (ANI) were analyzed for eight isolates, revealing diverse genetic profiles and novel sequence types (STs). Minimum spanning tree analysis indicated potential clonal spread of certain STs across different geographic regions. Antimicrobial resistance genes (ARGs) were detected in all isolates, with a high prevalence of genes conferring resistance to carbapenems, highlighting the challenge of antimicrobial resistance in Acinetobacter spp. infections. Mobile genetic elements (MGEs) carrying ARGs were also identified, emphasizing the role of horizontal gene transfer in spreading resistance. Evaluation of virulence-associated genes revealed a diverse range of virulence factors, including those related to biofilm formation and antibiotic resistance. However, no direct correlation was found between virulence-associated genes in Acinetobacter spp. and specific clinical outcomes, such as infection severity or patient mortality. This complexity suggests that factors beyond gene presence may influence disease progression and outcomes. This study emphasizes the importance of continued surveillance and molecular epidemiological studies to combat the spread of multidrug-resistant (MDR) Acinetobacter non-baumannii strains. The findings provide valuable insights into the epidemiology and genetic characteristics of this bacteria in southern Thailand, with implications for infection control and antimicrobial management efforts.

Bacterioplankton play a vital role in maintaining the functions and services of lake ecosystems. Understanding the diversity and distribution patterns of bacterioplankton, particularly the presence of potential pathogenic bacterial communities, is crucial for safeguarding human health. In this study, we employed 16S rRNA gene amplicon sequencing to investigate the diversity and geographic patterns of bacterioplankton communities, as well as potential pathogens, in eight volcanic lakes located in the Arxan UNESCO Global Geopark (in the Greater Khingan Mountains of China). Our results revealed that the bacterial communities primarily comprised Bacteroidota (45.3%), Proteobacteria (33.1%), and Actinobacteria (9.0%) at the phylum level. At the genus level, prominent taxa included Flavobacterium (31.5%), Acinetobacter (11.0%), Chryseobacterium (7.9%), and CL500-29 marine group (5.6%). Among the bacterioplankton, we identified 34 pathogen genera (165 amplicon sequence variants [ASVs]), with Acinetobacter (59.8%), Rahnella (18.3%), Brevundimonas (9.6%), and Pseudomonas (5.8%) being the most dominant. Our findings demonstrated distinct biogeographic patterns in the bacterial communities at the local scale, driven by a combination of dispersal limitation and environmental factors influenced by human activities. Notably, approximately 15.3% of the bacterioplankton reads in the Arxan lakes were identified as potential pathogens, underscoring the potential risks to public health in these popular tourist destinations. This study provides the first comprehensive insight into the diversity of bacterioplankton in mountain lake ecosystems affected by high tourist activity, laying the groundwork for effective control measures against bacterial pathogens.

Acinetobacter bereziniae has recently gained medical notoriety due to its emergence as a multidrug resistance and healthcare-associated pathogen. In this study, we report the whole-genome characterization of an A. bereziniae strain (A321) recovered from an infected semiaquatic turtle, as well as a comparative analysis of A. bereziniae strains circulating at the human-animal-environment interface. Strain A321 displayed a multidrug resistance profile to medically important antimicrobials, which was supported by a wide resistome. The novel Tn5393m transposon and a qnrB19-bearing ColE1-like plasmid were identified in A321 strain. Novel OXA-229-like β-lactamases were detected and expression of OXA-931 demonstrated a 2-64-fold increase in the minimum inhibitory concentration for β-lactam agents. Comparative genomic analysis revealed that most A. bereziniae strains did not carry any antimicrobial resistance genes (ARGs); however, some strains from China, Brazil, and India harbored six or more ARGs. Furthermore, A. bereziniae strains harbored conserved virulence genes. These results add valuable information regarding the spread of ARGs and mobile genetic elements that could be shared not only between A. bereziniae but also by other bacteria of clinical interest. This study also demonstrates that A. bereziniae can spill over from anthropogenic sources into natural environments and subsequently be transmitted to non-human hosts, making this a potential One Health bacteria that require close surveillance.

Emergence of carbapenem-resistant A. baumannii (CRAB) is a global, ongoing healthcare concern. CRAB is among the topmost priority pathogens, with various studies focusing on its global population structure and resistant allelic profiles. However, carbapenem-susceptible A. baumannii (CSAB) isolates are often overlooked due to their sensitivity to beta-lactams, which can provide important insights into origin of CRAB lineages and isolates. In the present study, we report genomic investigation of CRAB and CSAB coexisting in Indian hospital setting. MLST based population structure and phylogenomics suggest they mainly follow distinct evolutionary routes forming two phylogroups. PG-I exclusively for a successful clone (ST2) of CRAB and PG-II comprises diversified CSAB isolates except PG3373, which is CRAB. Additionally, there are few CRAB isolates not belonging to PG-I and sharing clonal relationship with CSAB isolates indicating role of genome plasticity towards extensive drug resistance in the nosocomial environment. Further, genealogical analysis depicts prominent role of recombination in emergence and evolution of a major CRAB lineage. Further, CRAB isolates are enriched in resistomes as compared to CSAB isolates, which were encoded on the genomic island. Such comparative genomic insights will aid in our understanding and localized management of rapidly evolving pandrug resistant nosocomial pathogens.

Acinetobacter baumannii is a gram-negative bacterium that causes hospital-acquired and opportunistic infections, resulting in pneumonia, sepsis, and severe wound infections that can be difficult to treat due to antimicrobial resistance and the formation of biofilms. There is an urgent need to develop novel antimicrobials to tackle the rapid increase in antimicrobial resistance, and antimicrobial peptides (AMPs) represent an additional class of potential agents with direct antimicrobial and/or host-defense activating activities. In this study, we present GATR-3, a synthetic, designed AMP that was modified from a cryptic peptide discovered in American alligator, as our lead peptide to target multidrug-resistant (MDR) A. baumannii. Antimicrobial susceptibility testing and antibiofilm assays were performed to assess GATR-3 against a panel of 8 MDR A. baumannii strains, including AB5075 and some clinical strains. The GATR-3 mechanism of action was determined to be via loss of membrane integrity as measured by DiSC3(5) and ethidium bromide assays. GATR-3 exhibited potent antimicrobial activity against all tested multidrug-resistant A. baumannii strains with rapid killing. Biofilms are difficult to treat and eradicate. Excitingly, GATR-3 inhibited biofilm formation and, more importantly, eradicated preformed biofilms of MDR A. baumannii AB5075, as evidenced by MBEC assays and scanning electron micrographs. GATR3 did not induce resistance in MDR A. baumannii, unlike colistin. Additionally, the toxicity of GATR-3 was evaluated using human red blood cells, HepG2 cells, and waxworms using hemolysis and MTT assays. GATR-3 demonstrated little to no cytotoxicity against HepG2 and red blood cells, even at 100 μg/mL. GATR-3 injection showed little toxicity in the waxworm model, resulting in a 90% survival rate. The therapeutic index of GATR-3 was estimated (based on the HC50/MIC against human RBCs) to be 1250. Overall, GATR-3 is a promising candidate to advance to preclinical testing to potentially treat MDR A. baumannii infections.

Animal carcass decomposition may bring serious harm to the environment, including pathogenic viruses, toxic gases and metabolites, and antibiotic resistance genes (ARGs). However, how wild mammal corpses decomposition influence and change ARGs in the environment has less explored. Through metagenomics, 16S rRNA gene sequencing, and physicochemical analysis, this study explored the succession patterns, influencing factors, and assembly process of ARGs and mobile genetic elements (MGEs) in gravesoil during long-term corpse decomposition of wild mammals. Our results indicate that the ARG and MGE communities related to wildlife corpses exhibited a pattern of differentiation first and then convergence. Different from the farmed animals, the decomposition of wild animals first reduced the diversity of ARGs and MGEs, and then recovered to a level similar to that of the control group (untreated soil). ARGs and MGEs of the gravesoil are mainly affected by deterministic processes in different stages. MGEs and bacterial community are the two most important factors affecting ARGs in gravesoil. It is worth noting that the decomposition of wild animal carcasses enriched different high-risk ARGs at different stages (bacA, mecA and floR), which have co-occurrence patterns with opportunistic pathogens (Comamonas and Acinetobacter), thereby posing a great threat to public health. These results are of great significance for wildlife corpse management and environmental and ecological safety.

Microbial community, as the decomposers of constructed wetland (CW), plays crucial role in biodegradation and biotransformation of pollutants, nutrient cycling and the maintenance of ecosystem balance. In this study, 9 water samples, 6 sediment samples, and 8 plant samples were collected in Annan CW, which has the functions of water treatment and wetland culture park. The characteristics of microbial community structure in different media were illustrated by using of high-throughput sequencing-based metagenomics approach and statistical analysis. Meanwhile, this study identified and classified human pathogens in CW to avoid potential risks to human health. The results showed that dominant bacteria phyla in CW include Proteobacteria, Bacteroides, Actinobacteria, Firmicutes and Verrucomicrobia. The distribution of microorganisms in three media is different, but not significant. And the pH and DO profoundly affected microbe abundance, followed by water temperature. The microbial diversity in sediments is the highest, which is similar with the detection of human pathogens in sediments. Moreover, compared with Calamus, Lythrum salicaria and Reed, Scirpus tabernaemontani has fewer pathogenic microorganisms. The distribution of microorganisms in the CW is complex, and a variety of human pathogens are detected, which is more prone to create potential risks to human health and should receive additional attention.

Acinetobacter baumannii is one of the most serious opportunistic pathogens according to WHO. The difference between bacterial and mammalian fatty acid biosynthesis pathways makes FASII enzymes attractive targets in drug discovery. 3-oxoacyl-[acyl-carrier-protein] synthase I (FabB) from the FAS II pathway catalyze the condensation of malonyl ACP with acyl-ACP, and elongates the fatty acid chain by two carbons. To investigate potential inhibitors of the A. baumannii FabB, we used computational approaches including homology modeling, high-throughput virtual screening, molecular docking, molecular dynamics simulations, and MM-GBSA free energy calculations. After the high-throughput virtual screening, the resulting ligands were further screened using the QM-polarized ligand docking (QPLD) and induced fit docking (IFD) approaches. Molecular dynamics simulations were performed for 100 ns. And according to binding free energy calculations, we have identified nine compounds with the best binding affinities. Three of these compounds were selected for an additional 1 μs MD simulation to assess ligand stability. Two of them named L6 and L7 showed promised stability and affinity to the target. Here, we present novel compounds against A. baumannii FabB via structure-based computational approaches. These compounds might pave the way for the design of new lead structures and inhibitors for multidrug-resistant A. baumannii.

Bread undergoes physicochemical processes known as 'staling', which limits shelf life and quality. Despite the fact that several chemical emulsifiers have been employed to combat this issue, they may offer risks to human health. In this investigation, the effects of bioemulsan, a natural bioemulsifier (BE), on bread quality and staleness were examined. The yield of emulsan generated by Acinetobacter calcoaceticus RAG-1 was 1.49 g/L. The presence of clear zones around colonies, high emulsification value of 100%, and remaining surface tension below 40 mN/m after heating (at 250 °C for 15-20 min) verified emulsan thermal stability. BE-supplemented bread had a greater moisture percentage than the control, resulting in reduced crumb hardening and improved bread quality during storage as measured by moisture content. The first day after adding 0.5% emulsan, the hardness rose from 90.45 N (for the control) to 150.45 N. Texture analysis showed that although the hardness increased during storage, adding emulsan allowed obtaining bread with clearly softer crumb after 2 and 3 days of baking, especially at 0.5% level (from 215.6 N for the control to 150.5 N for 0.5% BE-enriched bread after 2 days, and from 425.7 to 210.25 N after 3 days). Based on the sensory evaluation results, emulsan did not lead to any unpleasant changes on bread organoleptic parameters. Therefore, using bioemulsifier RAG-1 as a green emulsifier and anti-staling agent found to be more promising.

Acinetobacter nosocomialis (A. nosocomialis) is a glucose non-fermentative, gram-negative bacillus that belongs to the Acinetobacter calcoaceticus-baumannii complex. In recent years, studies have found an increased clinical prevalence of A. nosocomialis. However, given the increasing trend of antibiotic resistance, developing new antibacterial agents is vital. Currently, research regarding bacteriophage therapy against A. nosocomialis is only limited.

Two A. nosocomialis bacteriophages, TCUAN1 and TCUAN2, were isolated from sewage. Experiments such as transmission electron microscopy (TEM), host-range analysis, and sequencing were performed to determine their biological and genomic characteristics. TCUAN2 were further subjected to in vivo experiments and their derived-endolysin were cloned and tested against their bacteria host.

Transmission electron microscopy revealed that TCUAN1 and TCUAN2 belong to Myoviridae and Podoviridae, respectively. Both phages show a broad host spectrum and rapid adsorption efficiency. Further biological analysis showed that TCUAN2 possesses a shorter latent period and larger burst size compared to TCUAN1. Because TCUAN2 showed a better antibacterial activity, it was injected into A. nosocomialis-infected mice which resulted in a significant decrease in bacterial load levels in the blood and increased the mice's survival. Finally, genomic analysis revealed that the complete nucleotide sequence of TCUAN1 is 49, 691 bps (containing 75 open reading frames) with a G + C content of 39.3%; whereas the complete nucleotide sequence of TCUAN2 is 41, 815 bps (containing 68 open reading frames) with a G + C content of 39.1%. The endolysin gene cloned and purified from TCUAN2 also showed antibacterial activity when used with a chelator EDTA.