Drug-resistant pneumococci in children with acute lower respiratory infections in Vietnam.

Background: Acute lower respiratory infections (ALRI), primarily pneumonia, are the leading cause of death in children under 5 years of age. Most of these deaths occur in Africa and southeast Asia. Increasing rates of drug resistance in pneumococcal strains emphasize the necessity of prevention of pneumococcal vaccines. The aim of the present study was to determine the frequency of drug resistance and the distribution of serotype of pneumococcal strains isolated from pediatric patients with ALRI in Vietnam. Methods: Two hundred and twenty pediatric patients with ALRI under 5 years of age were enrolled in Hanoi, Vietnam between 2001 and 2002. Bacterial pathogens with a heavy growth (10(6) c.f.u./mL) were isolated from nasopharyngeal secretions on quantitative culture. Fifty-three pneumococcal strains isolated from the nasopharynx of pediatric patients were examined for antibiotic susceptibility including drug-resistant genes and serotyping. Results: A total of 73.6% of pneumococcal strains were genotypic penicillin-resistant Streptococcus pnemoniae (gPRSP), possessing altered penicillin-binding protein genes pbp 1a + 2x + 2b; 67.9% of these strains were gPRSP and simultaneously had the ermB gene, which is responsible for high resistance to erythromycin. The majority of gPRSP strains were serotype 19F or 23F. Conclusion: gPRSP strains with serotype 19F or 23F are highly prevalent among pediatric patients with ALRI under 5 years of age in Hanoi, Vietnam.