Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh

The main objective of this study was to investigate the prevalence of bla _NDM-1 in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla _NDM-1 gene. Among 403 isolates, 14 (3.5 %) were positive for bla _NDM-1, and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla _NDM-1-positive isolates were resistant to multiple antibiotics. Among β-lactamase genes, bla _{CTX-M-1-group} was detected in ten isolates (eight bla _CTX-M-15), bla _OXA-1-group in six, bla _TEM in nine, bla _SHV in seven, and bla _VIM and bla _CMY in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60–100 MDa) carrying bla _NDM-1 were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.