staph and strep

Question 1

staphylococcus

Answer 1

gram pos, non motile cocci, pairs, short chains and clusters
facultative anaerobes (diverse)

indigenous bacteria (part of normal flora) alimentary tract (nasopharynx)
The ones that are clinically active make coagulase

Coagulase (differentiates S. aureus, contributes to clotting it converts fibrinogen to fibrin

satph vs strep
staph produce catalase when growing in aerobic conditions

Question 2

Protein a

Answer 2

unique to staph. aureus

Major protein component of cell wall bound to peptidoglycan. With IgG fc region binding to protein A

Mess with that Fc region to disrupt opsonization-> macrophage

Question 3

Toxins produced by s aureus

Answer 3

hemolysins, leukotoxins, enterotoxins (toxic shock syndrome), exfoliatative toxins

Question 4

Hemolysins

Answer 4

alpha, beta and gamma
staph hemolysins are beta hemolysins

rbc membrane damaging proteins

Question 5

leukotoxins

Answer 5

attacks pmn leukocyte and macrophage

Question 6

enterotoxins

Answer 6

large family of staphylococcus toxins
Superanitgens:
cause diarrhea and emesis, intoxicaion symptoms within a few hours, toxins are heat stable, toxic shock syndrome
enterotoxins and tsst bind directly on the mhc and tcr independent of antigen stimulating 20 % of ALL t cells

massive cytokine production–> crazy immune responsd

Question 7

exfoloative toxin

Answer 7

lysis in epidermis by proteases causes skin stuff

Question 8

strepto coccus pneumonia

Answer 8

gram postitive cocci in pairs or chains
most species are faculatative anaerobic, ferment carbs resultinc in lactic acid production need blood or serum to grow
catalase negative as opposed to staphylococci

Question 9

classification of the streptococci

Answer 9

classification is based on 3 overlapping schemes:
1. cell wall carb Ag: lancefield typing Group a strep: s. pyogenes, Group B: s. agalactiae

2. hemolytic pattern on agar with alpha (partial hemolysis or beta with complete or gamma with no
3. biochemical properties