Aetiological agents of cerebrospinal meningitis: a retrospective study from a teaching hospital in Ghana

Meningitis is an important cause of morbidity and mortality in low-resource settings. In sub-Saharan Africa, the meningitis belt has been characterized by particularly high and seasonal incidences of bacterial meningitis extending throughout life. Despite the progress being made in treating the condition, the mortality rates continue to be high, ranging between 2% and 30% globally. In Ghana, the mortality rate of meningitis has been estimated to range from 36% to 50%. However little information is available on the pathogens contributing to meningitis and their antimicrobial susceptibilities. Updated information is essential to adjust the recommendations for empirical treatment or prevention of meningitis which could have immense implications for local and global health.

We retrospectively reviewed laboratory records of all patients suspected of bacterial meningitis who underwent a lumbar puncture from January 1, 2008 to December 31, 2010. Data were retrieved from laboratory record books and double entered into a Microsoft(®) excel spreadsheet.

Records of 4,955 cerebrospinal fluid samples were analysed. Of these, 163 (3.3%, 95%CI: 2.8% to 3.8%) were confirmed meningitis and 106 (2.1%, 95%CI: 1.7% to 2.6%) were probable meningitis cases. Confirmed meningitis cases were made up of 117 (71.8%) culture positive bacteria, 19 (11.7%) culture positive Cryptococcus neoformans and 27(16.6%) Gram positive bacteria with negative culture. The most prevalent bacteria was Streptococcus pneumoniae 91 (77.7%), followed by E.coli 4 (3.4%), Salmonella species 4 (3.4%), Neisseria meningitidis 3 (2.5%), Pseudomonas species 3(2.5%) and others. Pneumococcal isolates susceptibility to penicillin, chloramphenicol and ceftriaxone were 98.9% (95%CI: 94.0% to 100.0%), 83.0% (95%CI: 73.4% to 90.1%) and 100.0% (95%CI: 95.8% to 100.0%) respectively.

Streptococcus pneumoniae is an important cause of meningitis among all age groups and its susceptibility to penicillin and ceftriaxone still remains very high. Ghanaians of all ages and possibly other developing countries in the meningitis belt could benefit from the use of the pneumococcal vaccine. Other bacterial and fungal pathogens should also be considered in the management of patients presenting with meningitis.