Antibiotic resistance patterns and the prevalence of ESBLs among strains of Acinetobacter baumannii isolated from clinical specimens

The aim of current study was to define the antibiotic susceptibility patterns and detect the prevalence of producing strains of Extended-Spectrum β-Lactamase (ESBL) in 400 Acinetobacter baumannii (A. baumannii) which had been isolated from 3 major hospitals in Tehran clinical samples with combined disk test, The majority of isolates were from blood specimens. the susceptibility tests were carried out according to the Clinical and laboratory Standards Institute (CLSI) guidelines using disk diffusion method in order to determine sensitivity of 100 isolates of A. baumannii to 11 antibiotics, Isolates of A.baumannii revealed the highest resistance to cefepime, ceftriaxone, amikacin, respectively but polymyxin B considered as effective drugs in this study, multidrug resistant in these strains were 70%. The Minimum Inhibitory Concentrations (MIC) were determined for cefepime in 91% and for ceftazidime in 84% of the studied isolates were MIC≥ 128 μg/ml, and finally the phenotypic method of combined disk test demonstrated that 20% of samples were ESBL positive. Regarding to production of ESBL in this bacterium and possibility of coding genes transformation to the other bacteria, reconsideration in antibiotics consumption patterns and as well as more attention to nosocomial infections control criteria are inevitable.