Editing Streptococcus (section)

==== Group A ====
Group A ''[[Streptococcus pyogenes|S. pyogenes]]''  is the causative agent in a wide range of [[group A streptococcal infection]]s (GAS). These [[infection]]s may be noninvasive or invasive. The noninvasive infections tend to be more common and less severe. The most common of these infections include [[streptococcal pharyngitis]] (strep throat) and [[impetigo]].<ref name="Cohen-Poradosu 2007">{{cite journal | vauthors = Cohen-Poradosu R, Kasper DL | title = Group A streptococcus epidemiology and vaccine implications | journal = Clinical Infectious Diseases | volume = 45 | issue = 7 | pages = 863–865 | date = October 2007 | pmid = 17806050 | doi = 10.1086/521263 | doi-access = free }}</ref> [[Scarlet fever]] is another example of Group A noninvasive infection.

The invasive infections caused by group A beta-hemolytic streptococci tend to be more severe and less common. This occurs when the bacterium is able to infect areas where it is not usually found, such as the [[blood]] and [[Organ (anatomy)|organ]]s.<ref>{{cite web|title=Streptococcal Infections (Invasive Group A Strep)|url=http://www.nyc.gov/html/doh/html/cd/cdstrep.shtml|publisher=New York City Department of Health and Mental Hygiene|access-date=21 November 2012|archive-date=6 November 2012|archive-url=https://web.archive.org/web/20121106194414/http://www.nyc.gov/html/doh///html/cd/cdstrep.shtml|url-status=dead}}</ref> The diseases that may be caused include streptococcal [[toxic shock syndrome]], [[necrotizing fasciitis]], [[pneumonia]], and [[bacteremia]].<ref name="Cohen-Poradosu 2007"/> Globally, GAS has been estimated to cause more than 500,000 deaths every year, making it one of the world's leading [[pathogen]]s.<ref name="Cohen-Poradosu 2007"/>

Additional complications may be caused by GAS, namely acute [[rheumatic fever]] and acute [[glomerulonephritis]]. [[Rheumatic fever]], a disease that affects the [[joints]], [[kidneys]], and [[heart valves]], is a consequence of untreated strep A infection caused not by the bacterium itself, but due to the antibodies created by the immune system to fight off the infection cross-reacting with other proteins in the body. This "cross-reaction" causes the body to essentially attack itself and leads to the damage above. A similar autoimmune mechanism initiated by [[Group A streptococcal infection|Group A beta-hemolytic streptococcal (GABHS) infection]] is hypothesized to cause [[PANDAS (disorder)|pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS)]], wherein autoimmune antibodies affect the basal ganglia, causing rapid onset of psychiatric, motor, sleep, and other symptoms in pediatric patients.

GAS infection is generally diagnosed with a [[rapid strep test]] or by culture.