Resistance Flashcards
define MRSA
staph aureus organisms resistant to the anti-staphylococcal penicillins (methicillin and oxacillin)
also resistant to ALL beta-lactams, including all generations of cephalosporins!!
what gene gives MRSA resistance
MecA
what are risk factors for MRSA infections
prior admin of antimicrobials (esp beta-lactams and fluoroquinolones), IV catheterization
what are the most common locations for MRSA infection
ear and skin
can treat topically :)
T/F: MRSA is not associated with increased risk of mortality
true
what infection is commonly caused by MRSP
pyoderma in dogs
what species is affected by methicillin resistant staph epidermidis infections
horses
how are MRSA/MRSP infections treated
based on C/S
sometimes are sensitive to doxycycline, chloramphenicol, TMS, rifampin
don’t always need the big gun
what topical antibiotic can be used for canine bacterial infections of the skin (including MRSP/MRSA)
bactoderm (mupiricin)
what are ESBLs
gram negative bacteria that produce beta-lactamases that provide resistance to penicillins and cephalosporins
how can you identify an ESBL on C/S
resistant to cefpodoxime
what are the common options for treatment of ESBLs
amikacin, imipenem, meropenem
clavamox may be an option in the urine but not always susceptible
what bacteria are commonly ESBLs
Klebsiella pneumoniae #1 in human med
E. coli may be #1 in vet med
also pseudomonas, salmonella, and others
what is a risk factor for ESBL infection
previous use of 3rd generation cephalosporins like cefovecin
which are the most common enterococci and what do you do about them
E. faecalis and E. faecium
usually just treat the other bug present and they go away. not usually virulent
when should you treat an infection with enterococci
pure, heavy growth and clinical signs present
what can be used to treat enterococci
options limited
ampicillin usually
vancomycin is tx of choice in people, so we want to reserve its use
what are the most common uses of rifampin
MRSP pyodermas in dogs/cats
R. equi in foals
reserve its use for methicillin resistant staphs b/c not much resistance yet!!
what do you need to remember about dosing rifampin
it can create resistance during use, so keep treatment course short
what are the most common uses of carbapenems
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!!
which carbapenem is best for use in small animals? why?
meropenem better than imipenem b/c it can go SQ and less likely to be nephrotoxic
what drug class are carbapenems in
beta-lactams, so they are pretty safe
what is the most common use of vancomycin
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)
what is the most common use of linezolid
MRSP pyoderma/surgical site infection in dogs
only if not susceptible to anything else or requiring oral administration
what is the most common use of nitrofurantoin
resistant UTI
only useful in urine! will not treat systemic infections
used most commonly of all the reserved drugs
if you have a resistant UTI that is only susceptible to imipenem, what should you do?
ask the lab for nitrofurantoin susceptibility before deciding to give imipenem
what is the most common use of fosfomycin
only UTIs in dogs, usually if resistant to nitrofurantoin
what is the most important thing to keep in mind with resistant infections
BIOSECURITY
when are enterococci such a concern that the CDC may get involved
when they are resistant to vancomycin
