Molecular characterization and resistance profile of nosocomial Acinetobacter baumannii intensive care unit of tertiary care hospital in Bangladesh.

This study was designed to investigate the resistance profile along with the genetic background of resistance to beta-lactam antibiotics among the nosocomial A. baumannii in Bangladesh. A. baumannii was confirmed by detecting blaoXA-51-like. Antibiotic susceptibility was determined by disk diffusion method. Agar dilution method was used to determine MIC of ceftazidime and imipenem. All A. baumannii were phenotypically screened for ampC, ESBL and MBL production. Genetic markers of antibiotic resistance. such as blaampC, blaOXA-51, 23, 40, 58 and 143, blaKPc, blaMp, blavi and blaNDM-j, genetic environment around blaADc and ISAbal upstream of blaoXA, were evaluated by PCR. Twenty-four (96%) A. baumannii were considered as MDR. 96% A. baumanii were resistant to amoxiclav, ceftazidime, ciprofloxacin and cefoxitin, 92% to cefotaxime and piperacillin-tazobactam, 88% to cefepime, amikacin and imipenem, 52% to sulbactam- cefoperazone and 40% were resistant to aztreonam. Everything were sensitive to colistin. The distribution of several beta-lactamase genes such as blaoxa-51 (100%), blaADC-like (92%), blaNDM-i (92%), EBC group (84%), blaoxa-23 (76%), blavm (72%), blacpc (44%), DHA group (24%), blaoxa-58 (16%), ACC group (8%) and CIT group (4%) were observed among the 25 A. baumannii. This is the first reported plasmid mediated ampC beta-lactamases in A. baumannii. blaoxa-51 was positive in 100%, blandm-i in 95.45%, blaoxa-23 in 77.27%, blavim in 72.73%, blakpc in 50% and blaOXA-58 in 18.18% of imipenem resistant isolates. MDR profile of nosocomial A. baumannii would highlight the importance of standard guideline of antimicrobials use and infection control policy in the hospitals of Bangladesh.