Things unique to Gram-positive bactiera

• ribitol or glycerol liked to peptidoglycan are major antigens of Strep and Staph

• lipoteichoic acid allows bacteria to adhere to fibronectin and cell surfaces; this is why Gram-positive infections proliferate in sinuses and around catheters

How to identify the flesh-eating bacteria

• Gram-positive cocci in chains

• β-hemolysis on blood plates

• sensitive to bacitracin

Colonial morphology

• clear β-hemolysis on plates were indicative of Group A Strep

• Pneumococci do not lyse blood cells but instead cause a green color on the plate. this is termed α-hemolysis

Agglutination by specific antisera coupled to latex beads

• specific antisera can be used to agglutinate unknown bacteria

• reagents are available to identify Group A, B, C, D Streptococci and Pneumococci

Category: Microbiology Notes