RÉSUMÉ
Klebsiella pneumoniae is an important agent of nosocomial infections, and is often associated to multidrug antibiotic resistance that limit therapeutic options. A study was performed to characterize antibiotic resistance among K. pneumoniae isolates identified in nosocomial infection at our hospital. 18 isolates (from 17 patients) collected between January and July 1997 were analyzed according to the Kirby-Bauer procedure, and characterized according to antibiotyping, cluster analysis and phenotypic identification of known 13-lactamases. Results showed a high percentage of resistance against trimetroprim-sulfamethoxazol, cloramphenicol, ciprofioxacin, gentamicin and cephalosporins. Furthermore, a high percentage of isolates demonstrated resistance against 13-lactams-13-lactamase inhibitors combinations. Antibiotyping and cluster analysis indicated 3 phenotypic grups, characterized by a minor group (22 percent) of highly susceptible strains and two multiresistant groups, being one of these, associated with an outbreak in an intensiva care unit. Phenotypic identification of known 13-lactamases suggests that extended spectrum 13-lactamases are prevalent and hyperproduced in highly resistant isolates