Dissemination of carbapenem resistance and plasmids encoding carbapenemases in Gram-negative bacteria isolated in India

Abstract

Background: Carbapenem resistance in Gram-negative bacteria is an ongoing public health problem of global dimensions leaving very few treatment options for infected patients. Objectives: To study the dissemination of plasmid-borne carbapenemase genes in Gram-negative bacteria from a diagnostic centre in Tamil Nadu, India. Methods: A total of 151 non-repetitive isolates belonging to 10 genera were collected between January 2015 and December 2016 from a diagnostic centre in Tamil Nadu. The isolates included Escherichia coli (57), Klebsiella pneumoniae (45), Pseudomonas aeruginosa (10), Salmonella Typhi (8), Enterobacter cloacae (8), Acinetobacter baumannii (7), Serratia marcescens (5), Achromobacter xylosoxidans (5), Proteus mirabilis (5), Klebsiella oxytoca (5) and Elizabethkingia meningoseptica (1). Results: Of the 151 isolates, 71% (107) and 68% (103) were found to be resistant to meropenem and imipenem, respectively. The most prevalent β-lactamase gene was blaNDM-1 (22), followed by blaOXA-181 (21), blaGES-1 (11), blaOXA-51 (9), blaGES-9 (8), blaOXA-23 (7) and blaIMP-1 (3). We also observed blaOXA-23 in E. coli (4), and three K. pneumoniae were positive for both, blaOXA-23 and blaOXA-51. Plasmid incompatibility (inc/rep) typing results showed that the resistance genes (11) were present in the isolates carrying plasmid-types IncX, IncA/C, IncFIA-FIB and IncFIIA. The plasmid-borne resistance genes in E. coli and K. pneumoniae were transferred to susceptible E. coli AB1157. Conclusions: This study highlights the prevalence of carbapenem resistance and the acquisition of plasmid-borne carbapenemase genes in Gram-negative bacteria isolated at this centre.