Survey New Delhi metalo-beta-lactamase variants in enterobacteria spp. isolated in Southern Vietnam

Abstract

The New Delhi Metallo-beta-lactamse (NDM) – a Carbapenemase is an enzyme that makes the bacteria resistant to a broad range of beta-lactam antibiotics. The 〖bla〗_NDM gene that synthesizes the enzyme is located on plasmid that has conjugation or mobilization to create the multi-drug resistant bacteria. Since the 〖bla〗_NDM gene is identified on the Enterobacteriaceae spp. and has variety in different populations, we investigated whether there are variants of the 〖bla〗_NDM gene in Enterobacteriaceae spp. in the Southern Vietnam. A total of 106 strains of the Escherichia coli, Klepsiella pneumoniae, Enterobacter cloacae, Salmonella spp. and Shigella spp. resistant to Carbapenem isolated from hospitalized patients in Southern Vietnam in 2011 and 2013 were selected in this study. Hodge test was performed to identify the phenotype of Carbapenemase producing bacteria and then NDM genotype was identified by PCR assay and deciphered by sequencing method. Using conjugation and poly reaction chain method, we demonstrated that plasmids carrying NDM gene can be transferred from one organism to others. Basing on the typical replicon region, we identified the types of plasmid by poly reaction chain based – replicon typing method. There are 5 multiplex PCR were performed to detect HI1, HI2, I1, X, L/M, N, FIA, FIB, W, Y, P, FIC, A/C, T and FIIAs ,and 3 simple PCR to detect F, K and B/O type. Besides NDM-1, 2 other types of NDM – NDM-3, NDM-4 are recognized in Southern Vietnam. There were eight types of plasmid that have conjugation and carry NDM gene found in the studied strains. These results exposed the variant of NDM gene in Southern Vietnam and suggested the potential of NDM to be a worldwide public health problem is great, and cooperative surveillance is needed. Key words: New Delhi Metallo-beta-lactamse (NDM) Carbapenemase Enterobacteriaceae spp. Sequencing method Plasmid typing PCR-based replicon typing method