Prevalence of plasmid-mediated AmpC β-lactamases in Escherichia coli and Klebsiella pneumonia at tertiary care hospital of Islamabad, Pakistan.

Enterobacteriaceae produces AmpC β-lactamases that make them resistant to commonly used antibiotics. AmpC β-lactamases can be chromosomal-mediated or plasmid-mediated AmpC β-lactamases (PABLs). The present study was undertaken to determine the occurrence of PABLs production in clinical isolates in Escherichia coli and Klebsiella pneumoniae. Among 1328 culture positive samples, 511 isolates were identified as E. coli (81.02%, n = 414) and K. pneumonia (18.98%, n = 97). Cefoxitin resistance was observed in E. coli (19.57%, n = 81) and K. pneumoniae (22.68%, n = 22). Out of these cefoxitin resistant isolates, 40.74% (n = 33) E. coli and 54.55% (n = 12) K. pneumoniae came out to be PABL producers. Prevalence of both PABLs and ESBLs in E. coli and K. pneumoniae was 29.24% (n = 8) and 47% (n = 5), respectively. Isolates coproducing PABLs and ESBL exhibited increased minimum inhibitory concentrations (MICs) for selected cephalosporins. This study documented a high frequency of PABLs producing isolates from hospital which may lead to serious therapeutic problem.