High frequency of simultaneous presence of ESBL and carbapenemase producers among nosocomial coliform isolates in Faisalabad, Pakistan

OBJECTIVES: The objective of the current study was to find prevalence of relevant ESBL and carbapenemase producing genes in nosocomial E. coli and K. pneumoniae isolates and to check phenotypic susceptibility of all ESBL positive isolates to carbapenems. METHODS: Forty ESBL producing clinical isolates of Escherichia coli (n=33) and Klebsiella pneumoniae (n=7) were examined for the presence of β-lactamase genes (CTX-M, CTX-M-1, 2, 3, 4 and TEM). Carbapenem resistance was checked phenotypically and by presence of blaNDM-1 gene. RESULTS: Nine (27%) were positive for CTX-M genes, and 10 (30%) for TEM among E. coli isolates. Importantly, six isolates showed co-existence of CTX-M and TEM genes. In K. pneumoniae, two (28%) isolates were positive for CTX-M and one (14%) for TEM genes. Eight (24%) E. coli and one (14%) K. pneumoniae isolates were positive for CTX-M-1. Respective figures for CTX-M-4 were three (10%) and one (14%). CTX-M-2 and CTX-M-3 groups were not represented. Twenty (50%) isolates were resistant to both imipenem and meropenem out of which only four isolates expressed blaNDM-1 gene. CONCLUSIONS: The significant presence of both ESBL and carbapenemase producers and co-existence of ESBL and carbapenemases in the same isolates is worrisome.