Micro: Staphylococci

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1

what distinguishes strep and staph

catalase (positive=staph)

2

what distinguishes staphylococcus and micrococcus

staph ferments glucose, micrococcus does NOT

3

how does s. aureus split from the rest of the staphylococci

staph is coagulase positive

4

how do s. saprophyticus and s. epidermidis split

s. saprophyticus is novobiocin resistant and s. epidermidis is not

5

what are the clinical manifestations of s. aureus

cutaneous abscesses
cellulitis
wound infections
endocarditis
osteomyelitis
pneumo post flu
food poisoning
TSS
SSS

6

what types of cutaneous absecess does s. aureas make

furuncles, carbuncles or abscesses in other tissues

7

what is the incubation time of s. aureus

1-8 hours

8

what does staph grow in for food poisoning

meats, dairy, bakery products

9

what causes staph food poisoning

enterotoxin

10

how long do symptoms of s. aureus food poisoning symptoms last

24-48 hours

11

what are the symptoms of TSS

fever, skin rash, hypotension, multiorgan system damage

12

how is s. aureus transmitted

survive for long periods on dry inanimate objects, humans major reservoirs, carried on skin and nose in 30% of individuals

if skin and mucus membranes disrupted, bacteria can enter and initiate infection

13

what are the toxins that s. aureus has

enterotoxin
TSST-1
exfoliatin
alpha toxin
catalase
coagulas
hyaluronidase
beta-lactamase
Panton-valentine leukocidin
misc: coagulase, fibronolysin, hyaluronidase, proteases, nucleases, lipases

14

what are the symptoms of enterotoxin

nausea and vomiting

15

how does enterotoxin work

stimulates release of IL-1 and IL-2

16

how many types of enterotxins are there

6, A through F

17

is enterotoxin heat resistant

moderately: not inactivatied by brief cooking

18

what happens to TSST-1

binds directly to MHC II molecules without intracellular processing

interaction with T cells results in release of large amounts of IL-1 and IL-2

19

how is TSST-1 produced

infected wounds or contaminated tampons

20

what is TSST-1 part of

pyogenic toxin superantigens

21

how many of s. aureus strains produce TSST-1

20%

22

what is exfoliatin mediated by

phage mediated

23

what is exfoliatin's diseasse

scalded skin syndrome

24

what is another name for alpha toxin

leukocidin

25

what does alpha toxin produce

hemolysis, necrosis of skin

produces pores in cell membranes

26

how many units of alpha toxin assemble in the cell membrane to form pores

six (hexamer)

27

what is the role of catalase

degrades H2O2 into O2 and H2O

28

what cell's killing action is counteracted by catalse

neutrophils

29

what is the role of coagulase

converts fibrinogen to fibrin so neutrophils can't penetrate clots to get to organisms

30

what is the role of hyaluronidase

hydrolyzes matrix of CT and facilitates spread in tissue

31

what ie the role of panton-valentine leukocidin

2 component toxin that forms pores in cell membranes, especially leukocytes

32

what is PVL a member of

cytotoxin (beta pore forming toxins)

33

what is PVL's presence associated with

increased virulence of certain strains of s. aureus

34

what specific organsim is particularly associated with necrotic lesions involving skin and mucosa and necrotic hemorrhagic pneumonia

community associated MRSA

35

what is PVL produced from

genetic material of bacteriophage that infects s. aureus making it more virulent

36

what are the virulence factors of s. aureus

teichoic acid
protein a
mutation in PBP mutations

37

what is techioic acid a polymer of

ribitol and glycerolphosphates

38

what is tecihoic acid involved in

adherence of organism to mucosal cells

39

what does teichoic acid do

mediates septic shock syndrome similar to lipid A in gram negative organisms

40

what does protein A do

binds nonspecifically to Fc portion of IgG

41

what does protein A interfere with

opsonization

42

what does a mutation in PBP do

renders organisms resistant to beta-lactamase stable penicillins (MRSA)
VRSA also possible

43

what do staph aureus lab tests look like

grape like clusters of gram positive cocci on gram stain

yellow/gold colonies on blood agar

beta hemolytic on blood agar

44

what important things are positive in s. aureus

catalse and coagulase positive

45

how much of s. aureus is penicllin resistant and due to what

95% penicillin resistant due to beta lactamase production

46

how do you treat s. aureus

beta lactamase stable penicillins or cephalosporins, beta lactamase inhibitors, or other antibiotics

47

what does s. saprophyticus cause

occasional cause of UTI in women

48

what is s. epidermidis involved in clinically

nosocomial bacteremia in indwelling vascular catheters

endocarditis with prostethci heart valves

infection of prosthetic materials in general

chronic osteomyelitis

ocular infections

49

what types of prosthetic materials are infected by s. epidermidis

IV catheters
CSF shunts
peritoneal dialysis catheters
prosthetic joints
vascular

50

when do people get ocular infections from s. epidermidis

endopthalmitis after ocular surgery

51

where can you find s. epidermidis

normal skin flora

52

what is part of the pathogenesis of s. epidermidis

exopolysaccharide (slime)- adheres organism to plastic surfaces

53

what do the lab tests look like for s. epidermidis

gp cocci

54

is s. epidermidis coagulase positiv

no

55

is epidermidis coagulase novobiocin sensitive

yes

56

what is the treatment for s. epiddermidis

vancomycin

removal of prosthetic material