Aerobic gram +ve cocci - staph

Question 1

What is a good growth media for staph?

Answer 1

Blood agar

Question 2

What is the main staph species that is a human pathogen?

Answer 2

Staph aureus

Question 3

What does aureus stand for?

Answer 3

Golden

Question 4

Are all staph aureus species golden?

Answer 4

No, only certain strains

Question 5

Are the majority of staph strains gold?

Answer 5

No

Question 6

Why is agar so good?

Answer 6

Very different melting and freezing points.

Question 7

What does staph mean?

Answer 7

Grape

Question 8

How is staph aureus identified?

Answer 8

ID by colonial and gram stain morphology

Coagulate positive

Question 9

Where does staph aureus inhabit?

Answer 9

Anterior part of nose, skin and throat

Question 10

What are the cell wall virulence factors of staph aureus?

Answer 10

Protein A

Fibronectin-binding protein

Question 11

What does protein A do?

Answer 11

Binds to the Fc portion of IgG and inhibits phagocytosis

Question 12

What does fibronectin normally do?

Answer 12

Our bodies produce fibronectin to coat our mucosal surfaces - by coating our respiratory tract, we block out gram -ve rod binding sites

Question 13

What does fibronectin do against gram positive bacteria?

Answer 13

It doesn’t block gram +ve binding (rather gram -ve rod binding)

Question 14

What happens regarding fibronectin when someone gets sick? How can they get pneumonia?

Answer 14

Acute phase reaction producing elastase which cleaves fibronectin off our mucosa.
This opens up gram -ve binding sites and staph aureus will be there no matter what.
These are the causes of hospital acquired pneumonia

Question 15

What other virulence factors does staph aureus have other than its cell wall virulence factors?

Answer 15

Membrane damaging exotoxins - alpha, beta, gamma, delta and leukocidin

superantigen exotoxins

Question 16

Proteins pumped out of cells, specifically manufactured by bacteria to be virulence factors that are released into the environment.

Answer 16

exotoxin

Question 17

Protein toxins that have an affinity for a relatively highly conserved region of the TCR, the MHC class II complex. They stimulate a massive T cell response with outpouring of T cell cytokines.

Answer 17

Superantigen exotoxins

Question 18

What are some superantigen exotoxins from staph aureus?

Answer 18

Exfoliatin
Enterotoxins A, B, C, D, E, G
Toxic Shock syndrome toxin

Question 19

What does exfoliatin cause?

Answer 19

staphylococcal scalded skin syndromes

Question 20

What do the staph enterotoxins cause

Answer 20

staphylococcal food poisoning

Question 21

Infection occurring after or on top of an earlier infection, especially following treatment with broad-spectrum antibiotics.

Answer 21

Superinfection (or more aptly named supra-infection)

Question 22

What are the 4 major diseases/syndromes that staphylococcus aureus can cause?

Answer 22

1. Localized abscess
   2 .Sepsis and acute endocarditis
2. Hospital-acquired and post-influenzal pneumonia
3. Toxin-associated syndromes

Question 23

Localized collection of pus

Answer 23

abscess

Question 24

What is the mainstay of therapy for a skin or soft tissue abscess?

Answer 24

Incision and drainage

Question 25

Localized abscess in bone

Answer 25

osteomyelitis

Question 26

What is important with abscesses?

Answer 26

let the pus out

Question 27

infection of the heart lining, including valves

Answer 27

endocarditis

Question 28

Staph abscesses that occur where there is a hair follicle.

Answer 28

Folliculitis / furunculosis

Question 29

Where can you never get folliculitis?

Answer 29

palms of hands and soles of feet

Question 30

What are the four variants of expanded staph scalded skin syndromes?

Answer 30

ritters disease classic scalded skin syndrome staphylococcal "scarlet fever" Bullous impetigo

Question 31

Ritters occurs in who?

Answer 31

Newborns

Question 32

What is ritters? Why do children get it?

Answer 32

Newborns don't have antibodies and their kidneys are not fully developed. They cannot get rid of the toxin - tend to desquamate at a very deep level - often fatal;

Question 33

If a woman enters the ER in a coma state, what should be removed, if present?

Answer 33

Tampon

Question 34

How did a particular brand of tampon lead to toxic shock syndrome?

Answer 34

25% of woman have staph aureus growing in their vagina - only a subset can cause TSS Usually anaerobic in the vagina - but if a tampon is added, so is oxygen Blood from menstruation also provides nutrients Divalent cations (Mg2+) inhibits toxin production, but this tampon was very good at binding magnesium The tampon was also so absorbant that it dried out the vagina, causing microfissures, allowing the staph to enter the blood

Question 35

How is toxic shock syndrome treated?

Answer 35

Removal of the source of intoxication - drain abscesses or remove tampon Aggressive IV fluid replenishment IV immunoglobulin

Question 36

When are antibiotics used for toxic shock syndrome?

Answer 36

mainly serve to prevent recurrences

Question 37

Mobile plasmid that breaks up penicillin type antibiotics

Answer 37

B-lactamase carrying plasmid

Question 38

What does CAMRSA stand for?

Answer 38

community acquired methicillin resistant staph aureus

Question 39

What is the special virulence factor of CAMRSA?

Answer 39

Panton-Valentine Leukocidin

Question 40

What does VISA stand for?

Answer 40

Vancomycin intermedaite staph

Question 41

What is the general trend of antibiotic resistance for staph aureus?

Answer 41

Getting more and more resistant

Question 42

What is CAMRSA not related to?

Answer 42

Hospital acquired MRSA

Question 43

What does CAMRSA produce?

Answer 43

Produces soft tissue abscesses which tend to relapse. | May cause sepsis

Question 44

What is the difference in terms of virulence and resistance between hospital acquired and community acquired MRSA?

Answer 44

Hospital - more resistant, less virulent | Community - more virulent, less resistant

Question 45

What is one way in which staph aureus and staph epi can be differentiated biochemically?

Answer 45

Staph aureus is coagulase positive | Staph epidermidis is coagulase negative

Question 46

Where does staph epi usually live?

Answer 46

Commensal bacterium of the skin

Question 47

How does staph epidermidis most often cause opportunistic infections?

Answer 47

Can cause opportunistic infections if you have a foreign body inserted like an IV line or through prosthetic devices

Question 48

What is needed to treat staph epi infections?

Answer 48

Vancomycin since it is very antibiotic resistant

Question 49

What does saprophyte mean?

Answer 49

Grows on dead, organic matter

Question 50

What does staph saprophyticus mostly cause?

Answer 50

2nd most common cause of UTI in young women

Question 51

Staph saprophyticus is coagulase __________.

Answer 51

negative

Question 52

Describe staph saprophyticus in terms of antibiotic resistance.

Answer 52

antibiotic susceptible