Invasive Pneumococcal Disease in Children Aged <5 Years Admitted to 3 Urban Hospitals in Ibadan, Nigeria

Background. Streptococcus pneumoniae remains a major cause of childhood morbidity and mortality in the world. The introduction of pneumococcal conjugate vaccine in developing countries will be facilitated by a clearer understanding of the disease burden for bacterial causes of pneumonia and meningitis and the prevalent serotypes of S. pneumoniae. Methods. We conducted a prospective, hospital-based surveillance for a 2-year period involving children aged 2-59 months at 3 urban hospitals in Ibadan, Nigeria, using standard microbiological methods with confirmation and further testing of isolates at the Medical Research Council Laboratories in The Gambia. Results. There were 1210 cases overall: 481 (39.8%) were meningitis, 399 (33.0%) were pneumonia, and 330 (27.2%) were bacteremia clinical syndromes. There were 24 cases of definite meningitis, of which 9 were caused by S. pneumoniae, 11 by Haemophilus influenzae type b, and 4 by Klebsiella species. Of the 90 culture-positive pneumonia cases, 9 were caused by S. pneumoniae, 2 by H. influenzae type b, and 79 by other species. Among cases of bacteremia, the pathogen isolation rate was 28.8% (95 of 330); the isolated species included S. pneumoniae (3 isolates), Staphylococcus aureus (20 isolates), Klebsiella species (13 isolates), Salmonella species (15 isolates), and Escherichia coli (6 isolates). Of the 23 S. pneumoniae isolates, 11 were serotyped; the serotypes found were 5 (5 isolates), 19F (3 isolates), and 4 (3 isolates), and 1 isolate was nontypeable. These isolates were all susceptible to penicillin. Eight of 9 patients with definite pneumococcal meningitis died, whereas all patients with pneumococcal pneumonia and septicemia survived. Conclusions. Of the pneumococcal serotypes identified, 55% were covered by the licensed 7-valent pneumococcal conjugate vaccine, whereas all are covered by the 10- and 13-valent vaccines.