Group A, beta-hemolytic strep
Spread by respiratory droplets or skin contact. Person to person.
Does not survive well in the environment.
Reservior - infected patient or healthy carriers (on skin, mucous membrane (esp nasopharyngeal)
Major cause, probably more than staph aureus
Most common bacterial cause, esp in 2 to 20 y.o.
Most cases are mild, compared to other etiology
Severe, purulent inflammation of posterior oropharynx and tonsillar area
Sunburn-like rash
Caused by staph aureus and strep pyogenes
Most commonly on lower legs
Treated with topical agent (mupirocin) and/or penicillin or first-generation cephalosporin
All age gropus.
Fiery red, advancing erythema, esp on face or lower limbs.
Purulent vaginal discharge plus systemically unwell
Cellulitis or necrotising fasciitis/myositis (cellulitis with necrosis)
+ toxic-shock-like syndrome (fever, hypotension, multi-organ involvement, sunburn-like rash)
Due to cross-reaction between the strep antigen (esp M protein) and antigens of the heart and joint tissues.
2 to 3 weeks after pharyngitis
Rheumatic fever is preventable with 10 days of antibiotics (and the reason for it)
1 week after pharyngitis or impetigo
Deposit of antigen-antibody complex on the glomerular basement membrane.
No evidence that antibiotic treatments prevent acute GN.
Colony morphology - small, opalescent, surrounded by large zone of beta hemolysis.
Serology - antibody to streptolysin-O (ASO test)
Serology - anti-DNAse B titers (ADB test) for strep skin infections.
First line - Penicillin G
Second line - clarithromycin, azithromycin (for penicillin allergy patients)
Drainage and debridement for necrotizing fasciitis/myositis
Prolonged prophylactic antibiotic therapy indicated after just one episode of rheumatic fever
Things to revise/add later:
Bibliography: LWW microbiology
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Created | 20040322 |