Epidemiology of invasive pneumococcal disease in bangladeshi children before introduction of pneumococcal conjugate vaccine

Background: Because Bangladesh intended to introduce pneumococcal conjugate vaccine (PCV)-10 in 2015, we examined the baseline burden of invasive pneumococcal disease (IPD) to measure impact of PCV. Methods: During 2007-2013, we performed blood and cerebrospinal fluid cultures in children <5 years old with suspected IPD identified through active surveillance at 4 hospitals. Isolates were serotyped by quellung and tested for antibiotic susceptibility by disc diffusion and E-test. Serotyping of culture-negative cases, detected by Binax or polymerase chain reaction, was done by sequential multiplex polymerase chain reaction. Trends in IPD case numbers were analyzed by serotype and clinical syndrome. Results: The study identified 752 IPD cases; 78% occurred in children <12 months old. Serotype information was available for 78% (442/568), including 197 of 323 culture-negative cases available for serotyping. We identified 50 serotypes; the most common serotypes were 2 (16%), 1 (10 %), 6B (7%), 14 (7%) and 5 (7%). PCV-10 and PCV-13 serotypes accounted for 46% (range 29%-57% by year) and 50% (range 37%-64% by year) of cases, respectively. Potential serotype coverage for meningitis and nonmeningitis cases was 45% and 49% for PCV-10, and 48% and 57% for PCV-13, respectively. Eighty-two percent of strains were susceptible to all antibiotics except cotrimoxazole. Conclusion: The distribution of serotypes causing IPD in Bangladeshi children is diverse, limiting the proportion of IPD cases PCV can prevent. However, PCV introduction is expected to have major benefits as the country has a high burden of IPD-related mortality, morbidity and disability.