Antimicrobial resistance of nasopharyngeal isolates of Streptococcus pneumoniae in healthy carriers: report of a study in 5-year-olds in Marcory, Abidjan, Côte d'Ivoire.

The increasing prevalence of antibiotic-resistant Streptococcus pneumoniae is of growing public health concern. The aim of this study was to assess resistance rates of S. pneumoniae to penicillin and other antimicrobial agents. Between November 1997 and February 1998 in a community health centre in Marcory, an Abidjan suburb, 138 S. pneumoniae strains were isolated from the nasopharynxes of 218 apparently healthy children aged 3-60 months. The sensitivity of the isolates was tested using the Kirby-Bauer method. In isolates with a possibly abnormal sensitivity to the Kirby-Bauer test, minimum inhibitory concentrations (MIC) were estimated using the E-test. Antimicrobials tested included penicillin G, amoxycillin, cefotaxime, cotrimoxazole, tetracycline, chloramphenicol, erythromycin, rifampicin and vancomycin. Twelve of 108 isolates (8.7%) had reduced sensitivity to penicillin G, and in three of them the MIC for penicillin reached at least 2 micrograms/ml. Resistance to amoxycillin and cefotaxime was lower than to penicillin (2.2%). With regard to cotrimoxazole, 37% were moderately resistant and 15.2% highly resistant. The lowest resistance rate observed was to rifampicin (2.2%) and the highest was to tetracycline (57.2%). Rates of resistance to erythromycin and chloramphenicol were 11.6% and 2.9%. All strains were sensitive to vancomycin. Multidrug resistance (MDR) was detected in 9.4% of S. pneumoniae isolates. In children, epidemiological surveillance of resistance can be monitored by bacteriological surveys, as shown in this study.