Abstract
A collection of 88 Escherichia coli and 22 Klebsiella pneumoniae strains previously studied for the carriage of bla (CTX-M-15) were screened for the presence of bla (ampC) using multiplex PCR, and analysed for antibiotic resistance and co-carriage of bla (ampC) and bla (CTX-M-15). Cefoxitin resistance was noticed in total of 41.8% isolates. Concomitant resistance to third and fourth generation cephalosporins, aztreonam, gentamicin, trimethoprim and ciprofloxacin was noted. A total of 20% (22/110) isolates (14.5% E. coli and 5.5% K. pneumoniae) carried plasmidic bla (ampC) of the CIT-family. Sequencing of the representative isolates revealed CMY-6 AmpC-beta-lactamase. Simultaneous occurrence of bla (ampC) and bla (CTX-M) was noticed in 77.3% (17/22) isolates. Plasmid analysis of the selected isolates showed the presence of a single plasmid of ca. similar to 23 kb. Curing and transconjugation experiments provided evidence of carriage of bla (CMY) and bla (CTX-M) on same plasmid. RAPD typing revealed the presence of bla (CMY) and bla (CTX-M) in a wider range of strains of E. coli and K. pneumoniae.