Streptococcus pyogenes Flashcards
What is the classification/structure of streptococcus pyogenes?
Gram positive cocci in pairs and chains.
What are the clinical manifestations of strep?
“Strep throat”; Impetigo; Scarlet fever.
What are some complications with recurring strep infections?
Acute rheumatic fever; poststreptococcal glomerulonephritis.
Testing used to detect Group A Strep.
Culture; Strep Antigen Detection; Strep Antibody Detection; ASO; Anti-DNase B testing; Streptozyme testing.
Describe the Lateral Flow Immunochromatographic Assay (LFA) for Group A Antigen testing.
Collected by a throat swab; Strep A is capture and immobilized with Anti-Strep A reacting to bind conjugated antibody.
Positive and Negative (Control Line).
Describe the principle of ASO testing.
ASO is an antibody that is targeted against streptolysin O (toxic enzyme) which can lyse RBCs.
Testing method for ASO.
Nephelometric method - uses light scatter to measure immune complexes that contain streptolysin antigen.
Is ASO elevated in skin related strep infections?
No.
What are the methodologies that can be used for Anti-DNase B testing?
Macrotiter; microtiter; EIA; Nephelometry
Anti-DNase B testing is especially useful for patients with what?
Acute glomerulonephritis post impetigo.
What are the advantages of Group A Strep PCR testing?
High sensitivity and culture confirmation is not required.
What are the disadvantages of Group A Strep PCR testing?
Cost; some instruments can be large; multiple instruments may be needed.
