The epidemiology of Streptococcus pneumoniae in northern Tanzania
To achieve representative bacterial surveillance it is important to have effective transport and storage media. In this thesis two transport media, STGG and SGG were evaluated and shown to be suitable for optimal transport and storage of S. pneumoniae. These media will be particularly useful for field studies in developing countries. A previously published serotyping technique based on amplification by PCR and RFLP of the first two genes of the capsulation locus, cpsA and cpsB, was evaluated and modified for use directly on clinical specimens. This method did not produce serotype specific data from a single PCR reaction so an alternative method was devised. PCR amplification of the whole capsulation locus (~20kbp) was adopted followed by restriction digestion to produce different patterns. It was shown that the patterns obtained were capable of discrimination to the serotype level. This technique is fully portable. In conjunction with a study to evaluate azithromycin distribution for the community wide treatment of trachoma, the impact of azithromycin on macrolide resistance in S. pneumoniae was assessed. No increase in macrolide resistance was found among pneumococcal isolates. Significant association was found between resistance to penicillin and co-trimoxazole, both commonly used antibiotics. Co-colonisation was found by isolates of different serotypes in a few carriers. Carriage was not found to last for more than a few months and familial transmission was not found to be an important mechanism of transmission in this population. The population structure of the penicillin non-susceptible pneumococci (PNSP) was studied using penicillin binding protein PCRs and RFLP. The results showed many different PBP genotypes suggesting that the population is polymictic and that there has been recent recombination of PBP genes. Pneumococcal penicillin resistance is thought to be evolving in this community independently of international clones.