high prevalence of multidrug resistance and metallo-beta-lactamase (mβl) producing acinetobacter baumannii isolated from patients in icu wards, hamadan, iran

background: acinetobacter baumannii is gram- negative opportunistic coccobacilli, the most important agent in nosocomial infections with high mortality rate. multidrug resistance in strains isolated from nosocomial infections , making it difficult to treat and sometimes impossible. the aim of the present study was to investigate antibiotic resistance in a. baumannii isolates from iranian patients in hamadan, west of iran. methods: in this cross sectional study 100 a. baumannii isolated from trachea, blood, urine, sputum and wound samples of patients bedridden in intensive care unit (icu) wards of three educational hospitals during june 2011 to october 2012 was included . isolates confirmed at species level using biochemical tests and tracing bla oxa-51 gene using polymerase chain reaction (pcr) and preserved frozen at -70 °c until examination. their susceptibility to 17 antibiotics was performed using kirby-bauer disc diffusion method. determination of minimum inhibitory concentration and metallo-beta-lactamase production was carried out using e-test method. results: resistance rate of isolates were 94%, 85%, 84%, 97%, 95% and 98% against meropenem, imipenem, amikacin, ciprofloxacin, piperacillin/tazobactam and cefotaxime, respectively. no resistant isolate was observed against tigecycline and also no sensitive isolate seen against aztreonam and cefotaxime. results of e-test illustrated that 99% of all isolates were metallo-beta-lactamase (mβl) producing, which were resistance to imipenem; also 85% of them were resistance to meropenem. mic50 and mic90 of the isolates were ≥256 and ≥32 mg/ml for imipenem and meropenem, respectively. conclusions: the antibiotic resistance against most of the antibiotics, especially carbapenems is very high in hamadan region. in addition colistin sulfate and tigecycline were most effective antibiotics and to be used in a. baumannii infections.