Outbreak of Efficiently Transferred Carbapenem-Resistant blaNDM-Producing Gram-Negative Bacilli Isolated from Neonatal Intensive Care Unit of an Indian Hospital

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-beta-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.