Nasopharyngeal carriage, antibiotic susceptibility patterns and serotype distribution of streptococcus pneumoniae among children under five in Cape Coast, Ghana

Abstract

The introduction of the 13 valent pneumococcal conjugate vaccine has been reported to reduce nasopharyngeal carriage of vaccine types of the pneumococcal serotypes and the antibiotic resistant strains of the bacteria. However, studies conducted have revealed serotype replacement of the vaccine types. The goal of this study was to determine the nasopharyngeal carriage and serotype distribution of S. pneumoniae among children under five years in the post-vaccination era. A cross-sectional study was conducted where nasopharyngeal swabs were taken from 398 children in the Cape Coast Metropolis. Pneumococcal isolates were identified using optochin sensitivity testing and the presence of lytA and cpsA genes. Isolates were subjected to antibiotic susceptibility testing against different classes of antibiotics. Multiplex PCR was done on the isolates to serotype and determine the presence of penicillin resistance genes such as PBP1a, PBP2b and PBP2x. The overall carriage prevalence was found to be 23.4%. About 51.6% of the isolates belonged to known serotypes. The most occurring serotypes were 6A/B (10.8%), 23F (8.6%), 14 (7.5%) and 19F (6.5%). All the isolates were susceptible to Levofloxacin whereas 60.2%, 87.1% and 64.5% were non-susceptible to oxacillin, co-Trimoxazole and tetracycline respectively. About 50.5% of the isolates were multidrug resistant. Most of the oxacillin non-susceptible isolates were vaccine serotypes. All the isolates contained at least one of the penicillin resistant genes. In conclusion, antibiotic resistant vaccine type serotypes still persist even though new non-vaccine serotypes were detected. This indicates the presence of newly emerged serotypes.