Environmental Spread of New Delhi Metallo-beta-Lactamase-1-Producing Multidrug-Resistant Bacteria in Dhaka, Bangladesh

摘要

Resistance to carbapenem antibiotics through the production of New Delhi metallo-beta-lactamase-1 (NDM-1) constitutes an emerging challenge in the treatment of bacterial infections. To monitor the possible source of the spread of these organisms in Dhaka, Bangladesh, we conducted a comparative analysis of wastewater samples from hospital-adjacent areas (HAR) and from community areas (COM), as well as public tap water samples, for the occurrence and characteristics of NDM-1-producing bacteria. Of 72 HAR samples tested, 51 (71) samples were positive for NDM-1-producing bacteria, as evidenced by phenotypic tests and the presence of the bla(NDM-1) gene, compared to 5 of 41 (12.1) samples from COM samples (P < 0.001). All tap water samples were negative for NDM-1-producing bacteria. Klebsiella pneumoniae (44) was the predominant bacterial species among bla(NDM-1)-positive isolates, followed by Escherichia coli (29), Acinetobacter spp. (15), and Enterobacter spp. (9). These bacteria were also positive for one or more other antibiotic resistance genes, including bla(CTX-M-1) (80), bla(CTX-M-15) (63), bla(TEM) (76), bla(SHV) (33), bla(CMY-2) (16), bla(OXA-48-like) (2), bla(OXA-1) (53), and bla(OXA-47-like) (60) genes. Around 40 of the isolates contained a qnr gene, while 50 had 16S rRNA methylase genes. The majority of isolates hosted multiple plasmids, and plasmids of 30 to 50 MDa carrying bla(NDM-1) were self-transmissible. Our results highlight a number of issues related to the characteristics and source of spread of multidrug-resistant bacteria as a potential public health threat. In view of the existing practice of discharging untreated liquid waste into the environment, hospitals in Dhaka city contribute to the potential dissemination of NDM-1-producing bacteria into the community.