Streptococcus pneumoniae and Haemophilus influenzae type b carriage in Chinese children aged 12-18 months in Shanghai, China: a cross-sectional study

Background: The bacteria Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib) are leading causes of childhood pneumonia and meningitis and are major contributors to worldwide mortality in children younger than 5 years of age. Asymptomatic nasopharyngeal carriage of pneumococcus and Hib was determined for healthy children in Shanghai in 2009. Methods: Children from 5 immunization clinics were enrolled in this study. Specimens from the nasopharynx were collected and cultured in Columbia and chocolate agar to identify pneumococcal and Hib carriage. Pneumococcal specimens were serotyped with the Neufeld test, and antibiotic resistance for pneumococcal and Hib specimens used the E-test method. Significance of risk factors for carriage was assessed through chi-square tests. Results: Among 614 children, 16.6 % had pneumococcal carriage and 8.0 % Hib carriage. The predominant serotype of pneumococcus that was isolated was 19 F (52.9 %); serotype coverage was 68.6 % for both 7-valent pneumococcal conjugate vaccine (PCV) and PCV-10, and 82.3 % for PCV-13. Household residency and father's education were both significantly related to pneumococcal and Hib carriage. The majority of S. pneumoniae isolates were sensitive to most antimicrobials but there were high levels of resistance to azithromycin (51.0 %) and erythromycin (51.0 %). Haemophilus influenzae isolates were sensitive to almost all antimicrobials tested although 12.2 % of isolates were resistant to ampicillin. Conclusions: The pneumococcal and Hib vaccines require payment, and the children with the highest burden of disease may not be receiving these vaccines. Moreover, the presence of high antibiotic susceptibility towards pneumococcus, and to a lesser extent towards Hib, underscores the need for preventive protection against these diseases. Public funding of pneumococcal and Hib vaccines would be one mechanism to increase uptake of these vaccines.