Epidemiological study of Streptococcus pneumoniae carriers in healthy primary-school children

To obtain information on the Streptococcus pneumoniae carrier state in Span ish children, 332 healthy 6-year-old children from nine primary schools in northern Spain were screened. Thirty-six percent of the children had positi ve cultures yielding 128 strains. Seventy-one strains belonged to 14 serogr oup/serotypes, the most frequent being 19, 23, 3, 24 and 11. Fifty-seven st rains were non typeable. The identification of strains with equivocal resul ts was confirmed at species level by means of hybridisation with a specific probe, pneumolysin-mediated agglutionation and a pathogenicity test in mic e. Sixty-four percent of strains showed resistance to penicillin. 22% of th ese also being resistant to cefotaxime. More than 40% of the strains were r esistant to trimethoprim-sulfamethoxazole, tetracycline and erythromycin. T wenty percent of the erythromycin-resistant strains were susceptible to cli ndamycin. Two strains were resistant to rifampicin and one strain was resis tant to ofloxacin. All strains were susceptible to vancomycin. Previous ant ibiotic administration and having siblings under the age of 2 years correla ted with the carriage of pneumococcus. There was no correlation with the ca rriage of antibiotic-resistant strains, or a record of previous infections, previous hospital admissions or having relatives with chronic respiratory disease.