Outbreak of Efficiently Transferred Carbapenem-Resistant <i>bla</i> _NDM -Producing Gram-Negative Bacilli Isolated from Neonatal Intensive Care Unit of an Indian Hospital

Abstract

The emergence of bla NDM particularly in Gram-negative bacteria is a burden on the health care system in developing countries. Hence, this study was initiated to screen New Delhi Metallo-β-lactamase (NDM)-producing Gram-negative bacterial strains from neonatal intensive care unit (NICU) of an Indian Hospital. A total of 18 bla NDM -producing isolates were detected in the present study. Out of 18 bla NDM variant isolates, 6 were Klebsiella pneumoniae , 4 Escherichia coli , 2 Enterobacter aerogenes , 1 Acinetobacter lwoffii , 1 Enterobacter cloacae , 3 Acinobacter baumannii, and 1 Cedecea davisae from NICU, showing resistance against all antibiotics, except colistin and polymixin. The transferability of resistance determinants was tested by conjugation. Transfer of bla NDM -producing strains was successful in all 18 strains. In the case of transconjugants, the minimum inhibitory concentration values were found to decrease. The bla NDM -producing isolates contained detectable plasmids of size 66, 38, and 6 kb. Plasmi/d-based replicon typing revealed the incompatibility types Inc (A/C, FIIA, FIC, K, F, W, FIA, P, X, FIB, B/O) in bla NDM -carrying isolates. This study revealed the outbreak of multiple variants of bla NDM (13 NDM-1, 4 NDM-5, and 1 NDM-7). Moreover, other resistance markers, viz. bla OXA-1 , bla C MY-1 , bla VIM-1 , and bla SHV-1 coassociated with bla NDM were also found. In this study, we reported NDM–producing C. davisae as a first report to the best of our knowledge. This study is an attempt to reveal the dissemination of bla NDM isolated from neonates in NICU and their efficient transferability among Gram-negative bacilli through horizontal gene transfer.