Journal de bactériologie et parasitologie

Abstrait

Phenotypic and Genotypic Differences in Invasive and Non-Invasive Strains of Streptococcus pneumoniae

Fariha Altaaf*, Abbas Muhammad

Streptococcus pneumoniae (S. pneumoniae) is a human pathogen and a major cause of mortality and morbidity throughout the world. Streptococcus pneumoniae is the causative agent of otitis media, pneumonia, meningitis and bacteremia. Children, elderly and patient with compromised immune system are at a higher risk to attain infection by these bacteria. According to immunochemistry of their capsular polysaccharide, S. pneumoniae has divided into more than 90 serotypes. Many surface proteins are present on S. pneumoniae e.g. surface protein A, pneumolycin, hyaluronate lyase etc. The capsule is a major virulent factor for pneumococci and it prevents the bacteria from phagocytosis by host’s immune system. Some antigenic determinants have also studied for their potential to prompt a protective immune response in different clinical trials and experiments. The population biology of S. pneumoniae has poorly understood. Most of the problems arise by the molecular characterization, well-sampled population from carriage and from various discloser pneumococcal diseases. To address this, a multilocus sequence typing scheme and database by sequencing-450 bp fragments of seven housekeeping loci from 295 isolates were developed. The allelic combination of seven loci gives a sequence type or allelic profile. This typing scheme was validated using pneumococci of known genetic relatedness and could resolves >6 billion sequence type. The multilocus sequence-typing scheme allocates a powerful new approach to the characterization of pneumococci, since it delivers molecular typing data that are electronically portable between laboratories, and which may use to probe aspects of the population and evolutionary biology of these organisms. In this project, we compared two different strains of S.pneumoniae to check which one is growing rapidly and observed the difference between invasive and non-invasive strains based on phenotype and genotype.