Bacteremia due to extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in a pediatric oncology ward: Clinical features and identification of different plasmids carrying both SHV-5 and TEM-1 genes

Thirteen patients who had 16 episodes of bacteremia were observed between 1 993 and 1997 in a pediatric oncology ward with a high background isolation rate of cefotaxime- or aztreonam-resistant gram-negative bacteria, Four blo od isolates were Escherichia coli and 12 were Klebsiella pneumonine, and th ese isolates harbored extended-spectrum beta-lactamases (ESBLs), All episod es of bacteremia were nosocomial, all except one of the episodes occurred i n neutropenic patients, and all patients were treated with piperacillin or ceftazidime with amikacin and cefazolin prior to the onset of bacteremia, N ine of 13 patients were receiving extended-spectrum beta-lactam treatment w hen the bacteremias caused by ESBL producers occurred. Molecular studies re vealed that four K. pneumoniae SHV-2-producing isolates from 1994 were of t he same clone. Other ESBL producers, including six that carried both TEM-1 and SHV-5, five that carried SHV-5 and one that carried SHV-2 alone, were u nrelated. In conclusion, SHV-5 was present in 11 of the 16 isolates and coe xisted with TEM-1 in 6 isolates. Acquisition of resistance genes probably o ccurred under antibiotic selection pressure. This study highlights the impo rtance of routine checks for and detection of ESBL producers. Effective the rapy against ESBL producers should he considered early for children who hav e malignancies and neutropenia and who are septic, despite treatment with a regimen that includes an extended-spectrum beta-lactam, in a clinical sett ing of an increased incidence of ESBL-producing bacteria.