micro 2 Flashcards
what are the general characteristics of Streptococci? 6
gram-positive
Catalase-negative, Immotile, non-spore-forming, and anaerobes
Bacitracin sensitive
what are the adherence factors of Strep pyogenes? (3)
a. M protein
B. F protein
C. Lipoteichoic acid
what are the virulence factors of Strep pyogenes (responsible for evasion)? (3)
1- capsule (hyaluronic acid, antiphagocytic)
2- M protein (causes rheumatic fever)
3- C5a peptidase
what are the toxins released by Strep pyogenes? (2)
1- SPE: streptococcal pyrogenic exotoxin > associated with scarlet fever.
2- Streptolysin:
▪ O: oxygen-labile and immunogenic (ASO titer in RF)
▪ S: oxygen-stable and non-immunogenic
what is quinsy?
it is a URT infection caused by strep pyogenes
hallmark: peritonsillar abscess
what is scarlet fever and how do we test for it?
C/P:
- Pharyngitis, strawberry tongue
- Diffuse erythematous rash
- Sandpaper rash and circumoral pallor
Tests:
1- Dick test
2- Schultz-Charlton reaction: for diagnosis
what is Erysipelas?
Severe rapidly progressive superficial cellulitis with a sharp line of demarcation
what are the examples of non-suppurative diseases of S. pyogenes and what are they sequelae for? (2)
Rheumatic fever: sequelae for pharyngitis
acute Glomerulonephritis: sequelae for skin infections
what is the C/P for Rheumatic arthritis?
Polyarticular arthritis (most common), carditis (most serious)
what shape are strep pneumonia colonies?
Draughtsman
gram-stain of strep pneumonia
GP lancet-shaped
diplococci
what is a-hemolytic strep’s sensitivity to Optochin
Optochin
(ethylhydrocupreine):
strep pneumonia: Sensitive
strep viridans: Resistant
what is the most common cause of pneumonia?
Strep pneumonia (pneumococcus)
what are the general characteristics of Bacillus anthracis? (5)
Gram-positive bacilli, strict aerobic
Non-hemolytic, non-motile, and spore-former
what are the cutaneous clinical manifestations of Bacillus anthracis?
Cutaneous (Commonest form): dark-colored eschar (malignant pustule), bone meal
