[Fecal colonization by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit].

BACKGROUND: Fecal colonization by multiresistant bacteria can be a source of nosocomial infections. The aim of this work was to study fecal colonization by Klebsiella pneumoniae in neonatal intensive care unit (NICU) patients and investigate the resistance profiles of the strains.
METHODS: From May to October 2001, 11 stool specimens were collected from each patient hospitalized in the NICU during this period (425 specimens). Antimicrobial susceptibility was determined in K. pneumoniae isolates, and 30 strains resistant to third-generation cephalosporins were tested by polymerase chain reaction (PCR) to detect the blaCTX-M-2 gene.
RESULTS: K. pneumoniae grew in the 66% of the samples. Extended-spectrum b-lactamases (ESBL) were detected in 82.5% of these strains (ESBL-K. pneumoniae), 54.3% of all the strains studied. Among the neonates colonized by ESBL-K. pneumoniae (56% of patients), significant differences in colonization rates were observed according to gestational age, but not according to the mode of delivery or sex. ESBL-K. pneumoniae strains showed a high frequency of gentamicin resistance (97.3%) and amikacin resistance (71.4%). Nevertheless, they were all susceptible to cefoxitin and imipenem, and more than 90% were also susceptible to ciprofloxacin and piperacillin-tazobactam. In all the cefotaxime-resistant strains, an amplicon consistent with a CTX-M-type beta -lactamase was found by PCR.
CONCLUSION: A high percentage of NICU patients were colonized with ESBL-K. pneumoniae strains belonging to the CTX-M family, with elevated rates of aminoglycoside resistance. Gestational age was the only variable associated with significant differences in colonization rates.