Identification of the serotypes of bacterial meningitis agents; implication for vaccine usage

BACKGROUND AND OBJECTIVES: Bacterial meningitis is one of the most serious infections and should be treated as emergency. As it has significant morbidity and mortality throughout the world, every country should have precise information regarding the etiological agents of disease and populations at risk to design public health prevention strategy. In the present study in addition of evaluation of common etiological agents (Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae) in bacterial meningitis cases, we sero-grouped or serotyped the obtained agents in order to predict the usefulness of existing vaccines against bacterial meningitis. MATERIALS AND METHODS: Cerebrospinal fluid of 182 suspected meningitis patients were collected, from which 114 cases were approved by biochemical, microbiological and molecular tests as bacterial meningitis. The isolated bacteria were serogrouped or serotyped to determine the dominant serotypes. RESULTS: Streptococcus pneumoniae accounted for 36%, Haemophilus influenza for 26% and Neisseria meningitidis for 14% of cases. From 13 serogroups of N. meningitides the most frequent serogroups, were meningococcus group B (51%), C(24%) A (18%), Z(2%), W135 (1%) and 3% was not identified. In H. influenzae group only serotype b (100%) have been identified and in pneumococcal meningitis the most common serotype among our cases were 18C (44%) followed by14 (17%), 19A (13%), 6A (9%), 7F (4%), 4(3%), 3 (3%), 9V (2%), 8 (2%), 23f (2%), 5 (1%). CONCLUSION: Since there is no nationwide mass immunization program for common agents of bacterial meningitis in Iran, the result of this study can be used to improve the existing vaccines to cover the detected serotypes and consequently reduce the incidence of bacterial meningitis.