Nasopharyngeal isolates of S. pneumoniae from healthy carriers and children with pneumonia: colonization rates and antimicrobial susceptibility

Objectives: to compare colonization rates and antimicrobial resistance of nasopharyngeal pneumococci in healthy carriers and children with pneumonia. Methods: a cross-sectional study. Healthy subjects of this study were selected from randomly chosen immunization centers and day-care centers, and those with pneumonia were selected in pediatric emergency rooms. Flexible pernasal alginate swabs were employed to collect nasopharyngeal pneumococci specimens. Isolation and identification were performed according to standard procedures. Minimum Inhibitory Concentrations were assessed by microdilution techniques. Results: we studied 911 children, 429 healthy controls (60% of carriers, 72% attending day care centers and 49% recruited in immunization centers) and 482 children with pneumonia (50% of carriers) (P=0.02). The Minimum Inhibitory Concentration of penicillin to 441 isolates detected 198 (45%) of intermediate and 16 (4%) fully resistant pneumococci. Antimicrobial resistance rates of isolates from healthy carriers and children with pneumonia were, respectively: penicillin 48% (37% for immunization centers and 55% for day-care centers) and 50% (P>0.05), erythromycin 28% and 19% (P=0.05); cotrimoxazole 81% and 76% (P>0.05), chloramphenicol 6% and 7% (P>0.05), rifampin 5 and 3% (P>0.05) ceftriaxone 2 and 4% (P>0.05) and vancomycin 0% in both groups. An association among pneumococcal resistance to penicillin, erythromycin and cotrimoxazole was detected. Conclusions: pneumococcal carriage rate was higher in healthy children than in children with pneumonia. Penicillin and cotrimoxazole resistance rates were high, especially among those attending day-care centers.

Streptococcus pneumoniae; antibiotic resistance; acute respiratory infection; pneumonia

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