Group A streptococcal infection

DiseaseDisorder infobox
Name = Streptococcus, group A, as the cause of diseases classified to other chapters
ICD10 = ICD10|B|95|0|b|95
ICD9 =
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".

Types of infection

Infections are largely categorized by the location of infection:

* 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

(Note that some of these diseases can be caused by other infectious agents as well.)

Complications

Acute rheumatic fever

Acute rheumatic fever (ARF) is a complication of a strep throat caused by particular strains of GAS. Although common in developing countries, ARF is rare in the United States, with small isolated outbreaks reported only occasionally. It is most common among children between 5-15 years of age. A family history of ARF may predispose an individual to the disease. Symptoms typically occur 18 days after an untreated strep throat. An acute attack lasts approximately 3 months. The most common clinical finding is a migratory arthritis involving multiple joints. The most serious complication is carditis, or heart inflammation (rheumatic heart disease), as this may lead to chronic heart disease and disability or death years after an attack. Less common findings include bumps or nodules under the skin (usually over the spine or other bony areas) and a red expanding rash on the trunk and extremities that recurs over weeks to months. Because of the different ways ARF presents itself, the disease may be difficult to diagnose. A neurological disorder, chorea, can occur months after an initial attack, causing jerky involuntary movements, muscle weakness, slurred speech, and personality changes. Initial episodes of ARF as well as recurrences can be prevented by treatment with appropriate antibiotics.

Post-streptococcal glomerulonephritis

Post-streptococcal glomerulonephritis (PSGN) is an uncommon complication of either a strep throat or a streptococcal skin infection. Symptoms of PSGN develop within 10 days following a strep throat or 3 weeks following a GAS skin infection. PSGN involves inflammation of the kidney. Symptoms include pale skin, lethargy, loss of appetite, headache and dull back pain. Clinical findings may include dark-colored urine, swelling of different parts of the body (edema), and high blood pressure. Treatment of PSGN consists of supportive care.

evere 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.

Severe Group A streptococcal infections often occur sporadically but can be spread by person-to-person contact. [Gamba MA, Martinelli M, Schaad HJ, Streuli RA, DiPersio J, Matter L, et al. Familial transmission of a serious disease producing group A streptococcus clone:case reports andreview. Clin Infect Dis 1997; 24: 1118-21. ] Close contacts of people affected by severe Group A streptococcal infections, defined as those who have had prolonged household contact in the week before the onset of illness, may be at increased risk of infection. This increased risk may be due to a combination of shared genetic susceptibility within the family, close contact with carriers, and the virulence of the Group A streptococcal strain that is involved. [Health Protection Agency, Group A Streptococcus Working Group (2004). Interim UK guidelines for management of close community contacts of invasive group A streptococcal disease. Commun Dis Public Health 2004; 7(4): 354-61. Available at: http://www.hpa.org.uk/cdph/issues/CDPHVol7/no4/guidelines1_4_04.pdf]

Public Health policies internationally reflect differing views of how the close contacts of people affected by severe Group A streptococcal infections should be treated. Health Canada [Guidelines for management of contacts of cases of invasive group A streptococcal disease (GAS) including streptococcal toxic shock syndrome (STSS) and necrotising fasciitis. Toronto, Ontario: Ministry of Health; 1995. Available at: http://www.microbiology.mtsinai.on.ca/protocols/pdf/k5b.pdf] and the US Centers for Disease Control [The Prevention of Invasive Group A Streptococcal Infections Workshop Participants. Prevention of invasive group A streptococcal disease among household contacts of cases patients and among postpartum and post surgical patients: Recommendations from the Centres for Disease Control andPrevention. Clin Infect Dis 2002; 35: 950-9.] recommend close contacts receive treatment with appropriate antibiotics; current UK Health Protection Agency guidance is that, for a number of reasons, close contacts should not receive antibiotics unless they are symptomatic but that they should receive information and advice to seek immediate medical attention if they develop symptoms. [Health Protection Agency, Group A Streptococcus Working Group (2004). Interim UK guidelines for management of close community contacts of invasive group A streptococcal disease. Commun Dis Public Health 2004; 7(4): 354-61. Available at: http://www.hpa.org.uk/cdph/issues/CDPHVol7/no4/guidelines1_4_04.pdf]

Relation with OCD

In recent years, children with obsessive compulsive disorder (OCD) thought to be caused by an autoimmune response to group A beta-hemolytic streptococcal infection (PANDAS) have been identified. This promises to bring increased understanding of the disorder's pathogenesis. [ [http://ocd.stanford.edu/treatment/history.html History of Treatment of OCD.] Stanford School of Medicine. Retrieved on 2007-04-12 [http://www.medscape.com/viewarticle/547096?rss] ]

References

Note: Elements of the original text of this article are taken from the NIH Fact Sheet "Group A Streptococcal Infections", dated March 1999. As a work of the U.S. Federal Government without any other copyright notice, this is assumed to be a public domain resource.

External links

* [http://www.niaid.nih.gov/factsheets/strep.htm Group A streptococcal infection] at National Institutes of Health
* [http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListDate/Page/1202487092166?p=1202487092166 Group A streptococcal infections - Frequently Asked Questions] at UK Health Protection Agency