Streptococcus pyogenes is a spherical, Gram-positive, nonmotile, nonsporeforming bacteria that is the cause of Group A streptococcal infections. S. pyogenes are one of the most common pathogens in humans and can cause many human diseases ranging from minor skin irritations to severe systemic infections. More than seven million cases of S. pyogenes infections are reported each year. Of the six-hundred-fifty-thousand severe infections reported each year it is estimated that twenty-five percent are fatal. Quicker and more accurate detection methods for individual types of S. pyogenes bacteria are under development. Most concentrate on the M protein that most streptococcus bacteria use to adhere to various host cells because it is believed to be the weakest point in the pathogen’s defense and because each of the M proteins is unique to each strain.
S. pyogenes is estimated to be carried by as much as fifteen percent of the population without presenting any signs of the disease, usually in the respiratory tract where the fermentation conditions best suited for S. pyogenes metabolism. Exposure by immune compromised individuals or vulnerable tissue can result in instantaneous infection. The normal incubation period is approximately one to three days in non-immune compromised individuals.
Typically, mild S. pyogenes infections begin in the throat (pharyngitis or “strep throat”) or on the skin (“impetigo”). Subcutaneous infections, like erysipelas and cellulitis, can become complicated because of the systemic effects of pyrogenic toxins and a wide array of virulence factors. Recently, an increasing number of cases of severe invasive infections that resist antibiotics such as necrotizing fasciitis or “flesh eating bacteria” and streptococcal toxic shock syndrome have been cited, and require severe measures to treat including, but not limited to, surgery.