A retrospective study of clinical Streptococcus pneumoniae isolates from four health facilities in South-West Nigeria

Abstract

Nigeria is currently one of the highest pneumococcal disease burdened countries not implementing routine pneumococcal conjugate vaccine (PCV) immunization and having limited clino-biological data on Streptococcus pneumoniae. This retrospective study provides phenotypic and genotypic data on 15 isolates of S. pneumoniae recovered from clinical samples provided by 75 bacteremia, asthma, pneumonia, otitis media, meningitis, severe malaria and sickle cell anaemia (SCA) patients, attending health facilities within the south-West region of the country. The recovered S. pneumoniae isolates were serotyped and had their antibiotic susceptibilities determined by disk diffusion and MIC assays. They were further analyzed for disparity by SDS-PAGE and RAPD analysis coupled with genotyping for ply and lyt genes to query virulence. Empirical antibiotic prescription and demographic data were also extracted from the patients’ medical records with consent. The 15 recovered S pneumoniae isolates belonged to 5 distinct serotypes: 19F (n = 6), 5 (n = 3) and 2 each of 6B, 9V and 23F. More isolates were recovered from children than adults and from invasive diseases than non-invasive ones. However, serotype 9V isolates (adults only) were distinctively invasive and genotyping revealed some levels of clonal diversity and virulence among the multi-drug resistant strains. All the strains were within the vaccine coverage of PCV-13. Key words: Streptococcus pneumoniae, serotypes, antibiotic susceptibility, random amplified polymorphic DNA (RAPD), pneumococcal conjugate vaccine coverage, Nigeria