Post-Vaccination Surveillance of Invasive Pneumococcal Disease in Ghana.

BACKGROUND

Streptococcus pneumoniae, also referred to as pneumococcus, is of immense public health significance. In particular, it causes severe invasive diseases among children. This has led to the recommendation of anti-pneumococcal prophylaxis, including the administration of penicillin and pneumococcal conjugate vaccines (PCVs), which have become available in about 90% of the countries in sub-Saharan Africa. Nonetheless, breakthrough disease still occurs. Also, PCVs can cause a shift in the distribution of pneumococcal serotypes, usually towards non-vaccine types. However, in many sub-Saharan African countries where PCVs have been introduced, there are hardly any comprehensive post-vaccination surveillance data on pneumococcus.

AIM: To describe the post-vaccination epidemiology of invasive pneumococcal disease (IPD) in Ghana, including the prevalence, serotype distribution and antibiotic resistance.

METHODS

The study was cross-sectional and involved 14,597 patients recruited at the Korle Bu Teaching Hospital, Greater Accra Regional Hospital, Princess Marie Louise Children's Hospital, Ho Regional Hospital, Eastern Regional Hospital, and Zonal Public Health and Reference Laboratory, Tamale. Specimens of cerebrospinal fluid (obtained by lumbar puncture) and blood were collected routinely from meningitis patients, while blood specimens were taken from pneumonia patients. These were cultured for S. pneumoniae following standard microbiological methods and subjected to antimicrobial susceptibility testing. The isolates were serotyped by the pneumotest latex agglutination kit, and the results confirmed by Quellung reaction, using serotype-specific antisera.

RESULTS

The overall prevalence of IPD was 0.66% (n = 97), varying across syndromes: bloodstream infections (0.53%, n = 38), meningitis (2.45%, n = 43), and pneumonia (0.28%, n = 16). The majority of the cases (56.70%, n = 55) occurred in the 11-20-year-old group. Ten pneumococcal serotypes were identified, with Serotype 1 being predominant (58.76%), followed by Serotypes 23B (11.34%), 33F (9.28%), and 12F (8.24%). Vaccine serotypes accounted for 81.44% of the isolates, while 18.56% were non-vaccine serotypes (23A, 23B, and 38). Antimicrobial resistance was highest against sulphamethoxazole-trimethoprim (52%), ampicillin (51%), and penicillin (46%). No resistance was observed against ciprofloxacin, levofloxacin, and vancomycin. The multidrug resistance proportion was 42.3% (n = 41).

CONCLUSIONS

Even in the post-vaccination era, vaccine-type IPD remains a significant public health issue in Ghana. The observed serotype distribution and antimicrobial resistance patterns warrant sustained surveillance, more adaptive vaccination policies, and rigorous antibiotic stewardship to effectively mitigate IPD burden.