Isolation and molecular characterization of New Delhi metallo-beta-lactamase-1 producing superbug in Bangladesh.

Introduction: New Delhi metallo-beta-lactamse-1 (NDM-1) producing superbugs create a global public health problem because of their resistance to most antibiotics. This study was conducted to determine the presence of MBL producers, including NDM-1 producers, in Bangladesh, along with the antimicrobial resistance patterns of these organisms. Methodology: Thirty-five isolates resistant to imipenem by disk diffusion technique were investigated for MBL production. Minimum inhibitory concentration (MIC) of imipenem was determined by agar dilution method. MBL producers were phenotypically detected by double disk synergy test and combined disk assay. Gene encoding bla IMP-1, bla IMP-2, bla VIM-1, bla VIM-2, bla NDM-1 and class 1 integron was identified by PCR. Results: Thirty-one (88.57%) MBL producers were detected by PCR, 24 (68.57%) by double disk synergy test, and 30 (85.71%) by combined disk assay. Eight (22.86%) were positive for bla NDM-1, 13 (37.15%) for bla VIM-1, 21 (60.00%) for bla VIM-2, 18 (51.43%) for bla IMP-1, and 9 (25.71%) for bla IMP-2. More than one bla MBL was present in 23 (65.71%) of the isolates. MIC of imipenem of MBL producers ranged from ≥256 µg/ml to ≤8 µg/ml. All the NDM-1 producing isolates carried class 1 integron. NDM-1 producers were 100% resistant to amoxicillin, cephradine, cefuroxime, ceftazidime, cefotaxime, ceftriaxone, aztreonam, gentamicin and piperacillin, 87.5% to amikacin, 75% to ciprofloxacin, and 62.5% to co-trimoxazole and the combination of tazobactam and piperacillin. All were sensitive to colistin. Conclusion: The results of this study provide insight into the presence of bla MBL, including bla NDM-1, in Bangladesh. Urgent epidemiological monitoring of MBL producers in Bangladesh may combat their rapid dissemination.