Prevalence and characterization of extended-spectrum beta-lactamases in Klebsiella pneumoniae and Escherichia coli isolates from Colombian hospitals.

Gram-negative pathogens harboring extended-spectrum beta-lactamases (ESBL) are widely prevalent in Latin America, but little is known about their prevalence in Colombia. A network of 8 tertiary care hospitals in Bogotá, Medellín, and Cali, Colombia, was formed in January 2002 to determine the prevalence of ESBL-producing Klebsiella pneumoniae and Escherichia coli. We characterized and established the molecular epidemiology of ESBLs from these hospitals. Data from 1074 E. coli and 394 K. pneumoniae isolates were obtained from hospital laboratories during 6 months. Isolates resistant to third-generation cephalosporins or aztreonam were sent to a central laboratory. The prevalence of strains with this phenotype was 32.6% in K. pneumoniae and 11.8% in E. coli from the intensive care units, with slightly lower percentages from wards. Although TEM and SHV enzymes were present, the dominant class was CTX-M. Molecular typing of chromosomal DNA showed that most strains were not clonal.