Prevalence of plasmid mediated bla(TEM-1) and bla(CTX-M-15) type extended spectrum beta-lactamases in patients with sepsis

Abstract

Objective: To characterize the bacterial pathogens in patients having gram negative septicaemia. Further, to evaluate the antimicrobial resistance and underlying molecular mechanisms in these strains.

Methods: A total number of 70 cases of gram negative sepsis were included in this prospective, open labeled, observational study. Standard methods for isolation and identification of bacteria were used. Antimicrobial susceptibility and ESBL testing was performed by the standard disc diffusion method. PCR amplification was performed to identify bla(CTX-M), bla(SHV) and bla(TEM) type ESBLs. Conjugation experiments were performed to show resistant marker transfer.

Results: The most prevalent isolates Escherichia coli (E. coli) 58.6%, Klebsiella Spp. 32.9% and Pseudomonas 8.6%, were resistant to most of the antimicrobials including cefazolin, ceftriaxone, cefuroxime, ampicillin and co-trimoxazole but sensitive to imipenem and meropenem. ESBL and MBL production was seen 7.3% and 12.2% of E. coli isolates respectively. Three isoaltes were found to have bla(CTX-M-15) and two of them also showed bla(TEM-1) type enxyme. Whereas, none of them showed bla(SHV). Conjugation experiments using J-53 cells confirmed these resistant markers as plasmid mediated.

Conclusions: This work highlights the molecular epidemiology of escalating antimicrobial resistance and likely switch over of bla(CTX-M-15) type extended spectrum beta-lactamases by bla(TEM) type ESBLs in India. Further, the antimicrobial resistance by horizontal gene transfer was predominant among Enterobacteraceae in the community setting.