Antibiotic resistance pattern and distribution of Vietnamese extended-spectrum- β lactamase (VEB-1) gene in Acinetobacter baumannii isolated from hospitalized patients in Kashan Shahid Beheshti hospital during 2013-2014

Background: Acinetobacter baumannii are widely distributed pathogens in hospitals. They have the ability to have various mechanisms of resistance. Multiple drug resistant (MDR) strains of A. baumannii have created therapeutic problems worldwide. The aim of the present study was to determine the antimicrobial susceptibility and detection of blaOXA51 and VEB-1 genes of A. baumannii isolated from clinical specimens in teaching hospital. Materials and Methods: A descriptive cross-sectional study was performed on 124 A. baumannii strains isolated from patients in Beheshti hospital, Kashan, Iran, during 2013-2014. At the species level, the isolates were identified by conventional biochemical tests and then confirmed by the Microgen kit (GNA). An antibiotic susceptibility test was performed for 17 antimicrobial agents according to the CLSI guidelines. Multiple drug resistant was defined as presence of resistance to three or more classes of antibiotics. The presence of blaOXA51 and VEB-1 genes was investigated using the polymerase chain reation. Results: Acinetobacter baumannii isolates demonstrated the highest resistance to ceftriaxone, ceftazidime and cefotaxime. All isolates were sensitive to colistin and polymyxin. All isolates were positive for blaOXA51. Thirty-two isolates (25.8) were positive for the VEB-1 gene. Conclusion: This study highlights the high frequency of MDR isolates. The VEB-1 gene, which produces extended spectrum beta lactamase enzymes and inactivates third generation cephalosporins, was positive in more than 25 of the samples

Sensitivity of levofloxacin in combination with ampicillin-sulbactam and tigecycline against multidrug-resistant Acinetobacter baumannii

Background and Objectives: The selection of alternative treatment options with antibiotic combinations may be used for successful managing of multidrug-resistant Acinetobacter baumannii. The aim of this study was to determine the synergistic effects of ampicillin-sulbactam combined with either levofloxacin or tigecycline against MDR A. baumannii. Materials and Methods: A total 124 of A.baumannii isolates collected from clinical samples of hospitalized patients which assessed for antibiotic susceptibility using disk diffusion method. E-test was used on 10 MDR A. baumannii isolates to determine the minimum inhibitory concentration (MIC) of ampicillin-sulbactam, levofloxacin and tigecycline. Any synergistic effects were evaluated at their own MIC using E-test assay at 37°C for 24 hours. Synergy was defined as a fractional inhibitory concentration index (FICI) of ≤0.5. Results: Levofloxacin plus ampicillin-sulbactam combination was found to have synergistic effects (FIC index: ≤0.5) in 90% of the isolates, but there was no synergistic effect for ampicillin-sulbactam/tigecycline and tigecycline/ levofloxacin combination. The antagonist effect in 50% of isolates (FIC index: >2) showed in combination of levofloxacin/tigecycline. Conclusion: The emergence of multidrug A. baumannii isolates requires evaluating by combination therapy. The combination of levofloxacin plus a bactericidal antibiotic such as ampicillin-sulbactam is recommended. Results should be confirmed by clinical studies. Keywords: Acinetobacter baumannii, Etest Methods, Microbial Drug Resistance, Synergistic effec

The synergistic activity of various antibiotics against multidrug-resistance acinetobacter baumannii isolates using the disk diffusion method

Bachground: Acinetobacter baumannii as an opportunistic gram-negative bacterium is the leading cause of nosocomial infections, especially in patients admitted to intensive care units. Given the increment of resistance to multidrug-resistant A. baumannii isolates and the lack of suitable treatment options, the needs for investigating new drugs or combinations of drugs are felt. The aim of this study was to determine the synergistic effects of Vancomycin in combination with Tigecycline, Levofloxacine, Gentamycin, Colistin and Meropenem and the combination of Colistin with Meropenem and Rifampin against the infections caused by multidrug-resistance A. baumanni isolates. Material and Methods: This experimental study was done on multi-drug A. baumannii isolates (n=10) from blood cultures, tracheal tube samples, sputum and the urine of patients hospitalized in the Beheshti Hospital between June 2014 and June 2015. Antibiotic susceptibility testing was performed by disk diffusion method according to CLSI standards. synergy testing was done by disk diffusion method. Results: On combining the Vancomycin with Tigecycline Levofloxacine, Gentamycin, Colistin and Meropenem, no synergy was detected. The combination of Colistin/Meropenem and Colistin/Rifampin were indifferent with no synergistic effect. Conclusion: The combination of other antibiotics could be considered as an alternative antibiotic treatment for multi-drug A. baumannii isolates. Due to the smaller sample size in our study, for taking better results the future studies should focus on well-designed in vitro models on a large scale

The synergistic activity of various antibiotics against multidrug-resistance acinetobacter baumannii isolates using the disk diffusion method

Bachground: Acinetobacter baumannii as an opportunistic gram-negative bacterium is the leading cause of nosocomial infections, especially in patients admitted to intensive care units. Given the increment of resistance to multidrug-resistant A. baumannii isolates and the lack of suitable treatment options, the needs for investigating new drugs or combinations of drugs are felt. The aim of this study was to determine the synergistic effects of Vancomycin in combination with Tigecycline, Levofloxacine, Gentamycin, Colistin and Meropenem and the combination of Colistin with Meropenem and Rifampin against the infections caused by multidrug-resistance A. baumanni isolates. Material and Methods: This experimental study was done on multi-drug A. baumannii isolates (n=10) from blood cultures, tracheal tube samples, sputum and the urine of patients hospitalized in the Beheshti Hospital between June 2014 and June 2015. Antibiotic susceptibility testing was performed by disk diffusion method according to CLSI standards. synergy testing was done by disk diffusion method. Results: On combining the Vancomycin with Tigecycline Levofloxacine, Gentamycin, Colistin and Meropenem, no synergy was detected. The combination of Colistin/Meropenem and Colistin/Rifampin were indifferent with no synergistic effect. Conclusion: The combination of other antibiotics could be considered as an alternative antibiotic treatment for multi-drug A. baumannii isolates. Due to the smaller sample size in our study, for taking better results the future studies should focus on well-designed in vitro models on a large scale

Emergence of multidrug resistant, extended-spectrum β-lactamase and metallo-β-lactamase strain of Acinetobacter baumannii in ICU ward of Kashan Beheshti Hospital during 2013-14

Background: Acinetobacter baumannii (A .baumannii) is a nosocomial opportunistic pathogen especially in intensive care unit (ICU) patients with innate resistance to many antibiotics. The aims of this study were to determine the antibiotic resistance patterns, the frequency of extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) enzymes among the A. baumannii isolated from tracheal tubes of hospitalized patients in ICU ward of Beheshti hospital (Kashan, Iran) during 2013-2014. Materials and Methods: A descriptive cross-sectional study was performed on 40 isolates of A .baumannii. Antibiotic susceptibility test for seventeen antimicrobial agents was performed according to the CLSIs guidelines. ESBL and MBL producing isolates were confirmed by double-disk diffusion test. The presence of blaOXA51 gene was investigated using PCR. Results: All of A. baumannii isolates were resistant to Piperacillin, Piperacillin-Tazo­bactam, Ceftazidime, Cefepime, Cefotaxime, Ceftriaxone, Meropenem, Imipenem, Ciprofloxacin, Levofloxacin, and Trimethoprim-Sulfamethoxazole; 100 of the isolates were multi-drug resistant (MDR). Two (5) and 26 (65) strains were ESBL- and MBL-positive, respectively. All isolates were positive for blaOXA-51 gene. Conclusions: The study emphasizes the high frequency of MDR in Kashan Shahid Beheshti hospital. Since the resistance genes are located on mobile elements, to prevent further spread of the infection, rapid identification of the mentioned strains is essential