[Antimicrobial susceptibility of Streptococcus pneumoniae in pediatric and adult population from Santiago, 1997-2003].

BACKGROUND In Chile, the emergence of drug-resistant strains of Streptococcus pneumoniae has complicated treatment decisions and may lead to treatment failures. AIM to examine antimicrobial resistance trends among pneumococcal isolates from the Catholic University Hospital between 1997 and 2003. MATERIAL AND METHODS During a seven-year period, we examined 901 strains of S. pneumoniae isolated from sterile and non-sterile samples from adult and pediatric population. RESULTS Overall, 20% of isolates showed intermediate resistance to penicillin (MIC: 0.12-1 microg/ml) y 10.8% high level of resistance to penicillin (MIC > or = 2 microg/ml). Pneumococcal resistance to penicillin did not change significantly during the study period, but it was more common in pediatric patients and isolates from non-sterile samples. No isolate had a MIC > or = 8 microg/ml for penicillin. Twenty one percent of pneumococcal strains were resistant to erythromycin, 41.6% to trimethoprim-sulfamethoxazole and 3.6% to chloramphenicol. Macrolides resistance tended to increase between 1997 and 2003. Fourteen percent of strains showed intermediate resistance (MIC: 1 microg/ml) and 2.5%, a high level of resistance to cefotaxime (MIC: > or = 2 microg/ml). No isolate had a CIM > or = 4 microg/ml for cefotaxime. Among those isolates with intermediate or high level of resistance to penicillin, there were significantly more isolates highly resistant to erythromycin, trimethoprim-sulfamethoxazole and cefotaxime. CONCLUSIONS Multidrug-resistant pneumococci are common and are increasing in our country, particularly in pediatric population, probably associated to indiscriminate ambulatory prescription of antimicrobials.