Bacteria Genomes - STREPTOCOCCUS PYOGENES

This human pathogen, also known as group A streptococcus (GAS) is the leading cause of bacterial pharyngitis and tonsillitis. It may also produce sinusitis, otitis, arthritis and bone infections. Some strains prefer skin, producing either superficial (impetigo) or deep (cellulitis) infections. Later, following skin infections an after effect of disease or injury can include rheumatic fever following respiratory infections and glomerulonephritis (a painful kidney disease) .

Streptococcus pyogenes is the leading causative agent of rheumatic fever. Despite its reputation as a disease gone-by, acute rheumatic fever remains the leading cause of heart disease among children worldwide epsecially in the third world. Recently Salt Lake City has been the site for two epidemics of rheumatic fever and researchers believe by sequencing both genomes and comparing them, that the pathogen had remained in the poulation for over 12 years before its resurgence.

Once inside a person, the bacteria often subvert the immune system, allowing them to attack heart tissue. In severe cases, surgery is required to replace damaged heart valves. Researchers have tried for many years to make the connection between bacterial infection and heart disease.

There are more than a hundred varieties of group A Streptococcus each of which is distinguished by the type of 'M' protein it has. The M proteins serve as important virulence factors that help the organism resist phagocytosis (cell eating). Two M18 proteins in particular caught the attention of the researchers. They look like another M18 protein, called SPEC, which triggers a massive immune reaction in host cells and leads to streptococcal toxic shock syndrome, these types of protein are called superantigens, which allow the bacterium to survive in the host for an extended period of time.

Occasionally, S. pyogenes causes rapid and progressive infection of subcutaneous tissue resulting in massive systematic inflammation and tissue destruction - hence the dramatic reports of "flesh-eating" bacteria.

References:

http://www.ebi.ac.uk/integr8/QuickSearch.do?action=doOrgSearch&organismName=Streptococcus+pyogenes
http://www.genomenewsnetwork.org/articles/03_02/rheumatic_bacterium.shtml