Retrospective Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. May 26, 2019; 7(10): 1111-1121
Published online May 26, 2019. doi: 10.12998/wjcc.v7.i10.1111
Risk factors and clinical responses of pneumonia patients with colistin-resistant Acinetobacter baumannii-calcoaceticus
Hande Aydemir, Hande Idil Tuz, Nihal Piskin, Guven Celebi, Canan Kulah, Furuzan Kokturk
Hande Aydemir, Hande Idil Tuz, Nihal Piskin, Guven Celebi, Department of Infectious Diseases and Clinical Microbiology, Zonguldak Bulent Ecevit University, Faculty of Medicine, Zonguldak 67100, Turkey
Canan Kulah, Department of Microbiology, Zonguldak Bulent Ecevit University, Faculty of Medicine, Zonguldak 67100, Turkey
Furuzan Kokturk, Department of Biostatistics, Zonguldak Bulent Ecevit University, Faculty of Medicine, Zonguldak 67100, Turkey
Author contributions: Aydemir H and Tuz HI contributed together to this work; Aydemir H, Piskin N and Celebi G designed research; Aydemir H, Tuz HI and Kulah C performed research; Kokturk F analyzed data; and Aydemir H wrote the paper.
Institutional review board statement: This study was approved by the ethics committee of Zonguldak Bulent Ecevit University Teaching and Research Hospital.
Informed consent statement: Patients were not required to give informed consent statement for this study due to the suggestion of ethical committee of our hospital. We did not use any personal data. The data which was used for this study is available from our hospital’s computer system. But written informed consent forms were taken for the agreement to treatment of pan-drug resistant Acinetobacter baumannii infections from patients or legal representatives.
Conflict-of-interest statement: All authors declare no conflicts of interest related to this article.
Data sharing statement: The datasets used and/or analyzed during this study available from the corresponding author on reasonable request.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Hande Aydemir, MD, Associate Professor, Department of Infectious Diseases and Clinical Microbiology, Zonguldak Bulent Ecevit University, Faculty of Medicine, Bülent Ecevit Üniversitesi Tıp fakültesi, Enfeksiyon hastalıkları A. D, Zonguldak 67100, Turkey. drhaydemir@yahoo.com
Telephone: +90-538-3712756 Fax: +90-372-2610264
Received: February 10, 2019
Peer-review started: February 12, 2019
First decision: April 18, 2019
Revised: April 24, 2019
Accepted: May 1, 2019
Article in press: May 1, 2019
Published online: May 26, 2019
ARTICLE HIGHLIGHTS
Research background

Acinetobacter species are simultaneously resistant to many antimicrobial agents, and treatment options are extremely limited. Although colistin appears to be the only remaining therapeutic option for extensively-resistant Acinetobacter infections, colistin resistance in Acinetobacter strains has been reported worldwide. Knowledge of the risk factors is important for colistin resistance. This study highlights risk factors of colistin resistance and salvage therapies in Acinetobacter sp. Infections.

Research motivation

Infections with resistant Acinetobacter strains were found to be associated with high mortality rates. Combination therapies were commonly recommended since resistance could develop during therapies. The main goals for control of multidrug-resistant Acinetobacter should be early recognition, knowing risk factors, aggressive control of spread of the resistant strains. The problem for treatment of nosocomial infections with extensively- or pandrug-resistant Acinetobacter strains may be solved in future with development of new antimicrobial agents targeting these resistant strains.

Research objectives

In our study we evaluated the clinical responses and the outcomes of ventilator-associated pneumonia (VAP) patients with resistant Acinetobacter strains. The risk factors for colistin resistance were also investigated.

Research methods

Between January 2015 and April 2018, 108 patients with VAP due to colistin-susceptible strains and 16 patients with colistin-resistant strains were included in this study retrospectively. These two groups were compared for the age, sex, comorbidities, prior receipt of antibiotics, mortality rates, APACHE II and SOFA scores, duration of microbiological cure and the clinical, laboratory, radiological, and microbiological responses. Mann-Whitney U test was used to compare continuous variables whereas Pearson’s χ2 test or Fisher’s Exact χ2 test was used to compare the categorical variables. The potential independent risk factors for infection with colistin resistant strains were identified by using a binary logistic regression model.

Research results

The median duration of microbiological cure (P < 0.001) was longer in colistin-resistant group. Clinical (P = 0.703), laboratory (P = 0.277), radiological (P = 0.551), microbiological response (P = 1.000) and infection related mortality rates (P = 0.603) did not differ between patients with pneumonia due to colistin-resistant and colistin-susceptible strains. Independent risk factors for pneumonia with colistin-resistant Acinetobacter strains were found to be high APACHE II scores (OR = 1.9, 95%CI: 1.4-2.7; P < 0.001) and prior receipt of teicoplanin (OR = 8.1, 95%CI: 1.0-63.3; P = 0.045). Different combination of antibiotic regimens included colistin, meropenem, ampicillin/sulbactam, amikacin and trimetoprim/sulfamethoxazole were given to patients with colistin-resistant strains. Among patients with infection due to colistin-resistant strains, seven of them were treated with antibiotic combinations included sulbactam. Clinical (6/7) and microbiological (5/7) response rates were quite high in these patients. Very limited data is available for the optimal therapy regimens of infections with pandrug-resistant Acinetobacter strains. Individual treatment combinations may be given to the patients with infection due to colistin-resistant Acinetobacter strains.

Research conclusions

High APACHE II scores and prior teicoplanin usage were found to be the risk factors for pneumonia due to colistin resistant Acinetobacter strains. Statistically significant difference was not found between the mortality rates of the patients with colistin-susceptible and colistin-resistant strains. Combination antibiotic regimens including sulbactam seemed to be more useful. Further prospective studies are needed to evaluate the optimal therapy regimens. As prior usage of teicoplanin was found to be an independent factor for colistin resistance, patients should be carefully treated with teicoplanin empirically.

Research perspectives

Prospective randomized-controlled studies investigating optimal therapy regimens or new antimicrobials targeting colistin resistant Acinetobacter strains are needed. Risk factors for colistin resistance should be well known and strict prevention and control methods should be used in intensive care units.