Molecular identification of TEM and SHV extended spectrum $\beta$-lactamase in clinical isolates of Acinetobacter baumannii from Tehran hospitals

Multidrug resistance (MDR) Acinetobacter baumannii, producing the extended-spectrum -lactamases (ESBL) is one of the major concerns in hospitals. According to the infection reports caused by A.baumannii in Iran, the aim of this study is to identify the genes encoding the -lactamases TEM and SHV in A.baumannii isolates in Tehran hospitals using PCR method. A total number of 200 clinical isolates A. baumanniii were diagnosed at first using culture methods and biochemical tests followed by antibiogram using 16 different antibiotics by disk diffusion method based on CLSI guidelines. The ESBL was determined by double disk synergy test (DDST) and the results were verified using combined disk method. PCR for determining the prevalence of genes was performed using specific primers for all isolates. There was a high antibiotic resistance among the isolates with a high MDR rate of 82.5% and 51% strains were producing ESBL. The minimum inhibitory concentration (MIC) rate of cefepime and ceftazidime in the isolates were 8-128 µg/ml. The prevalence of TEM and SHV were respectively 56% and 63%. These results indicate the necessity of a monitoring program to timely identify these strains to prevent the resistance spread and increase efficient antibiotics usage.