Resistance

Question 1

define MRSA

Answer 1

staph aureus organisms resistant to the anti-staphylococcal penicillins (methicillin and oxacillin)
also resistant to ALL beta-lactams, including all generations of cephalosporins!!

Question 2

what gene gives MRSA resistance

Answer 2

MecA

Question 3

what are risk factors for MRSA infections

Answer 3

prior admin of antimicrobials (esp beta-lactams and fluoroquinolones), IV catheterization

Question 4

what are the most common locations for MRSA infection

Answer 4

ear and skin
can treat topically :)

Question 5

T/F: MRSA is not associated with increased risk of mortality

Answer 5

true

Question 6

what infection is commonly caused by MRSP

Answer 6

pyoderma in dogs

Question 7

what species is affected by methicillin resistant staph epidermidis infections

Answer 7

horses

Question 8

how are MRSA/MRSP infections treated

Answer 8

based on C/S
sometimes are sensitive to doxycycline, chloramphenicol, TMS, rifampin
don’t always need the big gun

Question 9

what topical antibiotic can be used for canine bacterial infections of the skin (including MRSP/MRSA)

Answer 9

bactoderm (mupiricin)

Question 10

what are ESBLs

Answer 10

gram negative bacteria that produce beta-lactamases that provide resistance to penicillins and cephalosporins

Question 11

how can you identify an ESBL on C/S

Answer 11

resistant to cefpodoxime

Question 12

what are the common options for treatment of ESBLs

Answer 12

amikacin, imipenem, meropenem
clavamox may be an option in the urine but not always susceptible

Question 13

what bacteria are commonly ESBLs

Answer 13

Klebsiella pneumoniae #1 in human med
E. coli may be #1 in vet med
also pseudomonas, salmonella, and others

Question 14

what is a risk factor for ESBL infection

Answer 14

previous use of 3rd generation cephalosporins like cefovecin

Question 15

which are the most common enterococci and what do you do about them

Answer 15

E. faecalis and E. faecium
usually just treat the other bug present and they go away. not usually virulent

Question 16

when should you treat an infection with enterococci

Answer 16

pure, heavy growth and clinical signs present

Question 17

what can be used to treat enterococci

Answer 17

options limited
ampicillin usually
vancomycin is tx of choice in people, so we want to reserve its use

Question 18

what are the most common uses of rifampin

Answer 18

MRSP pyodermas in dogs/cats
R. equi in foals

reserve its use for methicillin resistant staphs b/c not much resistance yet!!

Question 19

what do you need to remember about dosing rifampin

Answer 19

it can create resistance during use, so keep treatment course short

Question 20

what are the most common uses of carbapenems

Answer 20

life-threatening, multi-drug resistant ESBL infections, pseudomonas

this is the last line of treatment in people, so only use it if it is your only option!!

Question 21

which carbapenem is best for use in small animals? why?

Answer 21

meropenem better than imipenem b/c it can go SQ and less likely to be nephrotoxic

Question 22

what drug class are carbapenems in

Answer 22

beta-lactams, so they are pretty safe

Question 23

what is the most common use of vancomycin

Answer 23

life-threatening clostridial infections only when C/S dictates it is the only option
(Dr. Davis has never used it, used for MRSA in humans)

Question 24

what is the most common use of linezolid

Answer 24

MRSP pyoderma/surgical site infection in dogs
only if not susceptible to anything else or requiring oral administration

Question 25

what is the most common use of nitrofurantoin

Answer 25

resistant UTI
only useful in urine! will not treat systemic infections

used most commonly of all the reserved drugs

Question 26

if you have a resistant UTI that is only susceptible to imipenem, what should you do?

Answer 26

ask the lab for nitrofurantoin susceptibility before deciding to give imipenem

Question 27

what is the most common use of fosfomycin

Answer 27

only UTIs in dogs, usually if resistant to nitrofurantoin

Question 28

what is the most important thing to keep in mind with resistant infections

Answer 28

BIOSECURITY

Question 29

when are enterococci such a concern that the CDC may get involved

Answer 29

when they are resistant to vancomycin