Multidrug Resistant Acinetobacer baumanni: the occurrence of polymyxin resistance in Rio de Janeiro

Higher prevalence of carbapenem-resistant A. baumannii infections has led to the return of old antimicrobials, such as polymyxins, "last-resort" drugs for the clinical therapy. This study aimed to determine the susceptibility profile of 60 A. baumannii isolates from a hospital in the city of Rio de Janeiro, 27 isolates obtained from patients in an outbreak in 2011, and a total of 33 isolates from both patients and the hospital environment collected in the 2014-15 period, in the same hospital. Isolates showed high levels (>= 80%) of resistance to the antimicrobials tested: piperacillin/tazobactam, cefotaxime, ciprofloxacin, cefepime, imipenem and meropenem. The highest resistance percentage presented in isolates from the 2011 period was to ciprofloxacin (96%). Regarding the environmental isolates, the highest resistance percentage was found to cefotaxime (94%). Among the 60 isolates tested, 19 (32%) were sensible to polymyxin B (MIC <= 2 mg/mL) and 41 (68%) were resistant (MIC >= 4 mg/mL), 27 were obtained from patients (20 from the 2011 period and 7 from the 2014-2015 period) and 14 from the hospital environment. The resistance to polymyxins is still rare; however, the extensive use of polymyxins has led to the emergence of resistant strains of A. baumannii.