Staphylococci

Question 1

Staph species mainly responsible for female outpatient UTIs

Answer 1

S. saprophyticus

Question 2

Staphylococcal “A” antimicrobials?

Answer 2

• penicillin
• oxacillin/cefoxitin
• erythromycin, azithromycin, clarithromycin
• clindamycin
• SxT

Question 3

Foreign-body related infections (FBRIs) are associated with _________ formation

Answer 3

biofilm

Question 4

Staph vs micrococci LYSOSTAPHIN

Answer 4

Staph: S
Microccoci: R

Question 5

3 cell structures involved in S. aureus pathogenicity?

Answer 5

• teichoic acids
• capsule
• protein A

Question 6

What is an “A” category of antimicrobials?

Answer 6

They are always tested and always reported

Question 7

How is MRSA screened using chromagars (interpretation)?

Answer 7

Potential MRSA will be able to grow on the plate (has cefoxitin) AND produces a colour change (substrate taken up is specific to S. aureus)

Question 8

True CoNS represented by?

Answer 8

S. epidermidis

Question 9

TC: POS staph that are NOT S. aureus?

Answer 9

Veterinary staph

• S. hyicus
• S. intermedius
• S. pseudointermedius

Question 10

What would S. aureus isolated from urine indicate?

Answer 10

Rare => infection spread from another body site

Question 11

Staph vs micrococci BACITRACIN (Taxo A)

Answer 11

Staph: R
Micrococci: S

Question 12

Purpose of testing cefoxitin with oxacillin?

Answer 12

Cefoxitin tested as a surrogate for oxacillin = not reported for use, rather to test for mecA resistance to oxacillin (and therefore other B-lactams)

Question 13

Species of CoNS implicated in 80-90% of CoNS infections?

Answer 13

S. epidermidis

Question 14

Classic S. aureus on BAP description + smear

Answer 14

BH med gold op

s/ gpc pr

Question 15

What does hematogenous mean?

Answer 15

Involving, spread by, or arising in the blood

Question 16

Reasons for false POS catalase test?

Answer 16

• blood from BAP

- reactive metals (loops)

Question 17

What is the anti-MRSA cephem?

Answer 17

Ceftaroline

Question 18

Staph atmospheric?

Answer 18

Facultative anaerobes

Question 19

S. aureus PYR neg or pos? Other staph?

Answer 19

PYR: NEG

Other staph PYR: POS

Question 20

Staph vs micrococci PIGMENT

Answer 20

Staph: golden
Micrococci: grey-yellow

Question 21

What is heteroresistance?

Answer 21

2 subpopulations within the same culture - 1 exhibits R and the other exhibits S to the same antimicrobial

Question 22

Micrococci atmospheric?

Answer 22

Obligate aerobes

Question 23

Colour of S. saprophyticus on BAP?

Answer 23

Chalky white

Question 24

Significance of S. lugdunensis as an emerging pathogen?

Answer 24

Serious infections in the absence of manipulation + many virulence factors similar to S. aureus

Question 25

2 main virulence factors of CoNS?

Answer 25

• biofilm formation

- inherent resistance to antibiotics

Question 26

Why is detection of heteroresistance important?

Answer 26

Resistant cells grow more slowly = need to ensure recovery

Question 27

3 conditions to enhance detection of heteroresistance?

Answer 27

• Longer incubation (full 24 hrs)
• Increase salt content (enhance growth of salt-resistant cells)
• Lower incubation temperature (33-35C to favour resistant cells)

Question 28

Purpose of chromagars for MRSA? Selective agent in it?

Answer 28

Used to screen for MRSA in patient samples

Cefoxitin (rather than oxacillin)

Question 29

S. lugdunensis colonizes where?

Answer 29

Groin

Question 30

Staph vs micrococci MODIFIED OXIDASE

Answer 30

Staph: NEG
Micrococci: POS

Question 31

Responsible for 40% of CSF shunt infections and many inpatient catheter-related bacteremia, UTI

Answer 31

S. epidermidis

Question 32

Reasons for false NEG catalase test?

Answer 32

• old cultures

- inactive reagent

Question 33

Classic S. aureus morpholohy?

Answer 33

BH med golden op