Resistencia de streptococcus pneumoniae a penicilina y su asociación con factores clínicos y epidemiológicos / Resistance of streptococcus pneumoniae to penicillin: clinical and epidemiological aspects

Background: Penicillin and third generation cephalosporin resistant pneumococcal isolates have emerged in Chile, mainly in the pediatric population. These isolates complicate therapeutic alternatives, specially among patients with central nervous system infections. Aim: To assess the frequency of penicillin and third generation cephalosporin resistance among isolates obtained from pediatric patients with invasive pneumococcal infections, and to study serotypes and clinical risk factors associated with resistance. Material and methods: Microbiological isolates obtained from children between April 1994 and May 1999 with pneumococcal invasive infections, were serotyped and analyzed according to their susceptibility to penicillin and cefotaxime by E-test and broth microdilution testing. Potential risk factors studied included patient's age, previous antibiotic use or admissions, comorbidity, and serotypes. Results: Seventy eight patients were studied. Penicillin-resistant pneumococcal isolates were detected in 35.9 percent of cases (21.8 percent with intermediate and 14.1 percent with high level resistance) without significant variation among different clinical conditions. Most of the high level penicillin-resistant pneumoccocal isolates had MIC ü4 µg/mL (8 out of 11 strains). One third of penicillin-resistant isolates also expressed cefotaxime resistance. Multivariate analysis indicated an age ²36 months (OR=6.8; IC 95 percent: 1.4 to 33.5) and serotype 14 (OR=6.3; IC 95 percent: 1.7 to 23.3) as factors associated with penicillin resistance. Conclusions: One third of the invasive pneumococcal isolates obtained from pediatric patients were resistant to penicillin. Risk factors involved a younger age and pneumococcal isolates belonging to serotype 14

Salmonella enteritidis: un patógeno emergente en Chile / Salmonella enteritidis: an emergent pathogen in Chile

Materials and methods: Cases of clinical infections by Salmonella enteritidis were recorder from bacteriological and demographic notifications obtained at The National Reference Laboratory for Enterobacteria. Infection rates were calculated using the total Chilean population and the population of the different Health Services along the country. Results: Until 1993, 13,57 Salmonella enteritidis strains per year were received at the Reference Laboratory. The figures increased to 478 and 432 in 1994 and 1995, respectively. National rates were 3,41 and 3.04 notifications/100.000 inhabitans in 1994 and 1995 respectively. Northern regions were the most affected and 90 percent of observed cases during 1994 came from Arica and Antofagasta. At the present time, 20 percent of cases are observed in Santiago, located in the mid-portion of the country. The outbreak has mainly affected children and young adults (yo percent of cases). Strains have been isolated from stool cultures, suggestig gastrointestinal infections as the main clinical presentation. More than 98 percent of strains are susceptible to chloramphenicol, ampicillin, tetracycline, sulfa-trimetroprim, cefotaxime or ciprofloxacin. Conclusions: The obtained data clearly indicate the existence of an epidemic outbreak of Salmonella enteritidis infections, with a geographic progression from North to South