Streptococci (Catalase negative)

Question 1

S. pneumoniae

Answer 1

Lancet-shaped G(+) Diplococcus. Encapsulated. Alpha-hemolytic. Optochin sensitive. IgA protease. Lysed by bile

Polysaccharide and conjugate vaccine. Most common cause of MOPS (Menengitis, Otitis Media, Pneumonia, Sinusitis) Rusty sputum, Sepsis in sickle cell anemia and splenectomy

Question 2

Viridans group

Answer 2

Multiple species: S. mitis, S. sanguis (endocarditis). Alpha-hemolytic. Optochin resistant

Subacute bacterial Endocarditis (S. Sanguis), dental work, dental carries (S. Mutans), oral flora.

Question 3

Group A (S. pyogenes)

Answer 3

Beta-hemolytic. Catalase negative. Bacitracin sensitive. Hyaluronic acid capsule. M-protein (binds fibrinogin).

“Pyogenic pus: Pharyngitis -> glom. neph and rheumatic. Cellulitis. Impetigo (more commonly preceeds glom. neph than pharangitis). Erysipelas.
Toxogenic: Scarlet fever (scarlet rash that spares the face, strawberry tongue, scarlet throat), Toxic Shock-like syndrome. Nec. fasciitis
Immunologic: Acute glomerulonephritis, Acute rheumatic fever (J♡NES criteria: Joints (polyarthritis), Carditis, Nodules (subcutaneous), Erythema marginatum, Sydenham’s chorea). ASO titer (detects recent infection).”

Question 4

Group B (S. agalactiae)

Answer 4

Beta-hemolytic. Bacitracin resistant. Hippurate test (+).

Colonizes vagina (mother). pneumonia, menengitis, sepsis (baby). CAMP factor (enlarges area of hemolysis caused by S. aureus). Peripartum infections (mother and baby).

Question 5

Group D Strep (Enterococcus)

Answer 5

E. faecalis, E. faecium. Grown in 6.5% NaCl. Penicillin G- resistant

UTI. Biliary tract infection. Subacute endocarditis. VRE (Vancomycin-resistant enterococci), Nosocomial

Question 6

Group D Strep (Non-Enterococcus)

Answer 6

S. Bovis, No growth in NaCl.

Colon Cancer. Bacteremia & endocarditis in colon cancer patients