Characterization of Pneumococcal Genes Involved in Bloodstream Invasion in a Mouse Model

Streptococcus pneumoniae (the pneumococcus) account for significant morbidity and mortality worldwide, causing life-threatening diseases such as pneumonia, bacteremia and meningitis. In this study, we used microarray analysis to compare gene expression patterns of either serotype 4 or serotype 6A pneumococci in the nasopharynx and blood of mice, as a model to identify genes involved in invasion of blood in the context of occult bacteremia in humans. Microarray experiments were performed on whole genome S. pneumoniae PCR arrays obtained from the Bacterial Microarray Group at St George's Hospital Medical School, London (http://bugs.sghms.ac.uk/). The array was designed using TIGR4 base strain annotation and extra target genes from strain R6. Pair-wise comparisons were made between the nasopharynx and blood RNA samples labeled with either Alexa Fluor 546 or Alexa Fluor 647 dye from the 48, 72 and 96 h time points.