Enterococcal Infections (cont.)
Important nosocomial pathogen
Vancomycin resistant Enterococcus
(VRE)
Enterococcus
Diagnostic Laboratory Tests
•Resistant to bile
•Esculin hydrolysis
•BEA media
Enterococcus
Group D Streptococcus
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Bile Esculin Agar |
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Bile Esculin Agar |
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NEG |
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Esculin
Bile
Assay
REVIEW
Lancefield Serogroup Classification of
Beta-Hemolytic Streptococci Important in
Human Disease
Group A Streptococci:
Streptococcus pyogenes
One of Most Important Human Pathogens
Suppurative Diseases: Pharyngitis; Scarlet Fever;
Cutaneous & Soft Tissue Infections; Systemic
Disease
Non-Suppurative Sequelae:ARF,RHD,AG
Group B Streptococci:
Streptococcus agalactiae
Systemic, Cutaneous, UTI's
Neonatal disease
Obstetric Complications
REVIEW
Nonsuppurative Sequelae of Acute Group A Streptococcal Infection
Acute Rheumatic Fever (ARF)
Inflammatory reaction characterized by arthritis, carditis, chorea (disorder of CNS with involuntary spastic movements), erythema marginatum (skin redness with defined margin), or subcutaneous nodules
Within 2-3 weeks following pharyngitis
•Epidemic pharyngitis: ARF in as many as 3%
•Sporadic pharyngitis: ARF in 1 per 1000
Morbidity & mortality linked to subsequent disease of heart valve
(Rheumatic Heart Disease)
Poorly understood pathogenesis with several proposed theories including cross-reactivity of heart tissues & strep AGNs
•?? (Type II hypersensitivity, exotoxins, direct invasion)REVIEW
Nonsuppurative Sequelae of Acute Group A Streptococcal Infection (cont.)
Acute Glomerulonephritis
Follows either respiratory (pharyngitis) or cutaneous (pyoderma) streptococcal infection
Associated with well-defined group of M-types Incidence varies from <1% to 10-15%
Most often seen in children manifesting as dark, smoky urine with RBC's, RBC casts, white blood cells, depressed serum complement, decreased glomerular filtration rate
Latent period: 1-2 weeks after skin infection and 2-3 weeks after pharyngitis
Granular accumulations of immunoglobulin due to deposition |
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of immune complexes within the kidney |
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(Type III Hypersensitivity) |
REVIEW |
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