Structure and Physiology
Streptococcus pyogenes is a Gram-positive, spherical, and facultative anaerobic bacterium. Similar in cellular morphology to Staphylococcus species, this species of bacteria grows in long chains versus the grape-like clusters observed as Staphylococcus. Known as the flesh eating bacteria, S. pyogenes is the most pathogenic bacterium in the whole genus. Antigen A is present on the cell wall of this microbe and can cause zones of beta-hemolysis. Beta-hemolysis is the complete disruption of erythrocytes and the release of hemoglobin. S. pyogenes also contains protein F, a fibronectin binding protein, that gives it the ability to adhere to epithelial cells along the respiratory tract. Protein M, another virulence factor, has a fibrillar coiled-coil that allows the bacterium to resist and reduce phagocytosis. With these virulence factors and the addition of a hyaluronic acid capsule, S. pyogenes is a highly effective pathogen.
Transmission and Disease
Infection from S. pyogenes usually starts from the surface of the skin or throat and then spreads deeper. The adhesion proteins allow S. pyogenes to strongly bind to host cell surfaces and then invade epithelial cells. The versatility of this bacterium makes it difficult to develop a vaccine to stop infection, but it does remain acutely sensitive to penicillin. The symptoms may include fever, severe pain, dizziness, and red rash at wound site. These can lead to illnesses such as strep throat, impetigo, scarlet fever, glomerulonephritis, and necrotizing fasciitis.
Because of the wide range of diseases and prevalence as an opportunistic pathogen that normally inhabits the skin, disinfection of this microorganism is critical. Similar to some Staphylococcus species, S. pyogenes can be difficult to disinfect but does demonstrate susceptibility to low level disinfectants.
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