Occurrence and transferability of b-lactam resistance inEnterobacteriaceae isolated inChildren's University Hospital in Bratislava

Occurrence and transferability of b-lactam resistance in 30 multi-resistantEscherichia coli, Klebsiella spp.,Enterobacter spp.,Pantoea agglomerans, Citrobacter freundii andSerratia marcescens strains isolated from children between 0 and 3 years of age is presented. The strains were resistant to ampicillin (30), cefoxitin (22), cefotaxime (30), ceftriaxone (30), ceftazidime (30) and aztreonam (28), but susceptible to cefepime (30) and imipenem (26). Twenty-eight of 30 isolates possessed a transferable resistance confirmed by conjugation and isolation of 79-89-kb plasmids. The b-lactam resistance was due to production of b-lactamases and ceftazidime proved to be stronger b-lactamase inductor than ceftriaxone. Twenty-five clinical isolates expressed transferable extended spectrum b-lactamases, and chromosomally encoded AmpC b-lactamase.