Determination of Antimicrobial Resistance and Resistant Genes in Acinetobacter Baumannii from Human Clinical Samples

Objective:The aim of this study is to determine the prevalence, antimicrobial resistance and various resistance genes in Acinetobacter baumannii (A baumannii) from human clinical specimens at the payambaran and Baqiyatallah Hospitals in the city of Tehran, Iran, over a period of six months (September 2012 to March 2013).Methods: A total of 500 samples including blood, phlegm, urine, cerebrospinal fluid (CSF) and pus were collected from patients on admission in these hospitals.A baumannii was identified by using standard microbiological procedures and conventional polymerase chain reaction (PCR) technique.Antimicrobial susceptibility test was performed according to clinical and laboratory standard institute (CLSI) guidelines using Kirby-Bauer disc diffusion technique, while different resistance genes were detected using PCR method.Results: A total of 121 A baumannii was detected out of 500 samples, representing 24.20% period prevalence.A baumannii was detected from all the sample groups, but a higher prevalence was observed in the blood (43.87%) and phlegm (24.11%).Antibiotic resistance profile showed higher resistance of A baumannii to tetracycline (90.90%), trimethoprim (61.98%) and cotrimoxazole (51.23%), followed by aminoglycosides (9.91-31.40%).Relatively low resistance was observed to cephalosporins (16.52-20.66%),quinolones (6.61-9.91%)and macrolides (8.26-14.04%),while the lowest resistance was observed to carbapenems (3.3-5.78%),chloramphenicol and nitrofurantoin.Highest detection for resistant genes was observed for tetA (58.67%), aac (3)- IV (56.19%), sul1 (55.37%) and dfrA1 (48.76%).Relatively low detection was observed for aad A1, bla-genes (SHV, CTX-M, OXA-like, VIM, SIM and IMP) and lowest detection was observed for cat1 and cmlA, while no qnr gene was detected.Conclusions: Multidrug-resistant Acinetobacter infections are posing an increasing threat to the population in these communities.Carbapenems provide an effective option against infections caused by resistant A baumannii.