Group A streptococcal infection overview

Overview
The group A streptococcus bacterium (Streptococcus pyogenes, or GAS) is a form of Streptococcus bacteria responsible for most cases of streptococcal illness. Other types (B, C, D, and G) may also cause infection. Several virulence factors contribute to the pathogenesis of GAS, such as M protein, hemolysins, and extracellular enzymes. For further explanation of these virulence factors, see the main article on Streptococcus pyogenes.

Also known as: Strep. throat, necrotizing fasciitis, impetigo.

Types of infection
Infections are largely categorized by the location of infection:

(Note that some of these diseases can be caused by other infectious agents as well.)
 * bacteremia -- bloodstream
 * impetigo, cellulitis, and erysipelas -- skin and underlying tissues
 * focal infections -- limited to a particular site. Bacteremia can be associated with these infections, but it is not always present. Treatment depends on the specific clinical findings. Types include:
 * pneumonia -- pulmonary alveolus
 * tonsillitis -- tonsils
 * septic arthritis -- joints
 * osteomyelitis -- bones
 * peritonitis -- peritoneum
 * meningitis -- meninges
 * necrotizing fasciitis -- skin, fascia and muscle
 * scarlet fever -- upper body
 * sinusitis - nose.
 * strep throat -- pharynx
 * toxic shock syndrome -- multiple systems

Severe streptococcal infections
Some strains of group A streptococci (GAS) cause severe infection. Those at greatest risk include children with chickenpox; persons with suppressed immune systems; burn victims; elderly persons with cellulitis, diabetes, blood vessel disease, or cancer; and persons taking steroid treatments or chemotherapy. Intravenous drug users also are at high risk. GAS is an important cause of puerperal fever world-wide, causing serious infection and, if not promptly diagnosed and treated, death in newly delivered mothers. Severe GAS disease may also occur in healthy persons with no known risk factors.

All severe GAS infections may lead to shock, multisystem organ failure, and death. Early recognition and treatment are critical. Diagnostic tests include blood counts and urinalysis as well as cultures of blood or fluid from a wound site. The antibiotic of choice is penicillin, to which GAS is particularly susceptible and has never been found to be resistant. Erythromycin and clindamycin are other treatment options, though resistance to these antibiotics exists.