Thirty-one strains of Klebsiella pneumoniae (including 10 duplicates) from 21 septicemic pediatric patients (age, <2 months) were studied during a 4-month period (June to October 1996) in which the fatality rate was 62% (13 of 21). These isolates identified by the API 20E system yielded the same biotype. Pulsed-field gel electrophoresis experiments revealed the same clone in 31 strains. The isolates were multidrug-resistant but were still susceptible to ciprofloxacin, imipenem, and cefoxitin. A 135-kb plasmid was harbored in all of the isolates. No transconjugants were obtained that were resistant to ampicillin, cefotaxime, tetracycline, or gentamicin. Isoelectric focusing for ␤-lactamases was performed on all strains, and three bands with pIs of 5.4, 7.6, and 8.2 were obtained. Of these, the pI 8.2 ␤-lactamase had an extended-spectrum ␤-lactamase phenotype. PCR amplification of both TEM-and SHV-type genes was obtained. The sequence analysis of the SHV PCR product indicated a mutation corresponding to the SHV-5 ␤-lactamase.Klebsiella pneumoniae is an important hospital-acquired pathogen with the potential of causing severe morbidity and mortality in pediatric patients. Several outbreaks of infection caused by K. pneumoniae isolates that are simultaneously resistant to broad-spectrum cephalosporins and aminoglycosides have been widely reported (8,9,18,21). Some of these multidrug-resistant isolates produce extended-spectrum ␤-lactamases (ESBLs) that are able to hydrolyze expanded-spectrum cephalosporins (e.g., ceftriaxone, cefotaxime, and ceftazidime), aztreonam, and related oxyimino-␤-lactams. Most of these enzymes are TEM-or SHV-type ␤-lactamases in which the substitution of one or more amino acids has altered the configuration of the active site (7,14,19). Most of the plasmids determining ESBLs are large (Ն80 kb) and encode multiple resistances (10). Little is known about the ESBL-producing Enterobacteriaceae in Mexico (23). The present work is a characterization of 31 ESBL-producing K. pneumoniae isolates from a nosocomial outbreak occurring in a hospital in Cuernavaca, Mexico. MATERIALS AND METHODSPatients and bacterial strains. The General Hospital in the state of Morelos is a secondary-care facility with 100 beds. The neonatal intensive care unit has 8 beds. An outbreak was suspected in the neonatal intensive care unit due to an increased number of isolates of K. pneumoniae from blood cultures during a 4-month period. A retrospective epidemiological investigation included 74 children less than 2 months old hospitalized from June to October 1996.Twenty-one clinical isolates were from blood; another 10 duplicate strains were from sites other than blood (urine and catheter tip) corresponding to 10 patients. In total there were 31 clinical isolates identified as K. pneumoniae by the API 20E system (BioMerieux, Merck).Susceptibility testing. The antimicrobial susceptibility was initially determined with the MicroScan (Dade) system, using the Combo 14 panel. Subsequently, MICs of several ␤-lactams were determine...

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In order to review the epidemiology of Gram-negative infections in the pediatric and neonatal intensive care units (PICUs and NICUs) of Latin America a systematic search of PubMed and targeted search of SciELO was performed to identify relevant articles published since 2005. Independent cohort data indicated that overall infection rates were higher in Latin American PICUs and NICUs versus developed countries (range, 5%-37% vs 6%-15%, respectively). Approximately one third of Latin American patients with an acquired PICU or NICU infection died, and crude mortality was higher among extremely low-birth-weight infants and those with an infection caused by Gram-negative bacteria. In studies reporting > 100 isolates, the frequency of Gram-negative pathogens varied from 31% (Colombia) to 63% (Mexico), with Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli the predominant pathogens in almost all countries, and Acinetobacter spp. and Serratia spp. isolated sporadically. The activity of quinolones and third-generation cephalosporins against P. aeruginosa, Acinetobacter spp., and Enterobacteria was seriously compromised, coincident with a high prevalence of circulating extended-spectrum β-lactamases. Furthermore, we identified two observational studies conducted in Chile and Brazil reporting infections by P. aeruginosa and Acinetobacter baumannii in PICUs, demonstrating resistance to carbapenems, and two outbreaks of carbapenem-resistant K. pneumoniae in Colombia and Brazil. The endemicity of multidrug-resistant Gram-negative infections in Latin American PICUs and NICUs is punctuated by intermittent clonal outbreaks. The problem may be alleviated by ensuring ICUs are less crowded, increasing staffing levels of better-trained health care personnel, and implementing antimicrobial stewardship and surveillance programs.