Practice Questions Flashcards
Which 3 antibiotic classes are LIPOPHILIC and can gain access to intracellular location as well as protected sites?
- FQs
- Phenicols
- Nitroimidazoles
Others: tetracyclines, macrolides, lincosamides, and pot. sulfas do NOT gain access to protected sites.
what 2 antibiotic classes are HYDROPHILIC?
- Beta lactams (penicillins and cephalosporins)
- Aminoglycosides
Give the MOA for the following antibiotic classes:
Beta-Lactams:
Aminoglycosides:
Tetracyclines:
Fluoroquinolones:
Pot. Sulfonamides:
Macrolides:
Lincosamides:
Phenicols:
Nitroimidazoles:
Beta-Lactams: cell wall synthesis inhibitors
Aminoglycosides: protein synthesis inhibitors at 30s
Tetracyclines: protein synthesis inhibitors at 30s
Fluoroquinolones: DNA gyrase inhibitors
Pot. Sulfonamides: Folic acid pathway inhibitors
Macrolides: protein synthesis inhibitors at 50s
Lincosamides: protein synthesis inhibitors at 50s
Phenicols: protein synthesis inhibitors at 50s
Nitroimidazoles: DNA synthesis inhibitors
What 4 antibiotic classes are TIME dependent?
- Beta-lactams (pen’s and ceph’s)*
- Potentiated sulfas
- Macrolides
- Lincosamides
What 4 antibiotic classes are CONCENTRATION dependent?
- Aminoglycosides*
- Fluoroquinolones*
- Tetracyclines
- Nitroimidazoles
Which 5 antibiotic classes are BACTERICIDAL?
- beta-lactams
- aminoglycosides
- fluoroquinolones
- pot. sulfas
- nitroimidazoles
which 4 antibiotic classes are BACTERIOSTATIC?
- tetracyclines
- macrolides
- lincosamides
- phenicols
Which antibiotic class would empirically cover giardia?
nitroimidazoles
Which antibiotic class covers gram negative aerobes (pseudomonas, brucella, campylobacter, lepto, actinobacillus, bordetella, E. coli) and staphs, but NOT streps or anaerobes?
Aminoglycosides
What is the spectrum for penicillins?
streps
anaerobes
what is the spectrum for cephalosporins?
streps
gram + anaerobes
gram negatives (better with higher generations; needs higher doses)
Which antibiotic class would be BEST for mannheimia or histophilus infections (gram negatives)?
Macrolides
These antibiotics also cover gram positives
T/F: a lincosamide is an appropriate choice for clostridial, actinomyces, or nocardia infection
true – lincosamides should cover gram positives and anaerobes. They are great for abscesses and prophylaxis prior to dental procedures
Which 4 antibiotic classes are considered “broad spectrum”?
- FQs (gram -, staphs, rickettsia, mycoplasma)
- Pot. sulfas (gram +, -, protozoa)
- Tetracyclines (gram +, -, anaerobes, rickettsia)
- Phenicols (gram + aerobes and anaerobes, mycoplasma, rickettsia)
What are the 2 major potential side effects of beta lactams?
mild GI signs
hypersensitivity
what are the 3 major potential adverse effects of aminoglycosides?
nephrotoxicity
ototoxicity
vestibular toxicity
Decrease toxicity and increase efficacy by dosing ONCE daily.
What are the major potential side effects of tetracyclines?
esophageal strictures in cats
if IV in horses, FATAL
skeletal and dental issues
what are the major potential side effects of FQs?
cartilage toxicity (young, heavier, active)
retinal toxicity (cats, enro>5 mg/kg)
bone marrow suppression and arrhythmogenesis (prado)
prohibited ELDU in food animals
T/F: FQs are prohibited for ELDU in food animals
true
What are the potential adverse side effects of pot. sulfas?
MANY in dogs – hypersensitivity, allergic rxns, cutaneous rxns, KCS, hypothyroidism, bone marrow suppression, urinary crystal formaton
safest in horses – some colitis risk
cats – slobbers
DECREASE risk of side effects if treat for <5 days.
What is the MOST severe adverse effect of macrolides and lincosamides in horses and rabbits?
FATAL diarrhea
What side effect can occur in foals prescribed macrolide antibiotics?
anhidrosis and hyperthermia
if combined with rifampin, also anemia and hepatotoxicity
T/F: a potential adverse side effect of lincosamide antibiotics in dogs is anorexia and vomiting
true
in cats – esophageal ulcers
why are phenicol antibiotics prohibited in food animals?
idiosyncratic irreversible aplastic anemia in ppl
what are the major adverse side effects of phenicol antibiotics?
hematologic toxicity - cats
non-palatible
florfenicol can cause dry eye
idiosyncratic aplastic anemia in ppl
what is the major potential side effect of nitroimidazoles?
neurotoxicity
T/F: nitroimidazoles are prohibited for ELDU in food animals
true
when is oral administration of antibiotics CONTRAINDICATED?
vomiting/diarrhea/GI disease
obstruction
anorexia
life-threatening illness
Though IM injections are tolerated well by patients and has reliable asborption, what is the downside to this administration route?
there is a risk of injection site reactions
when should you NOT choose SQ administration route?
dehydrated patients and horses (too large of volume)
IV administration is well tolerated by patients usually and achieves the highest absorption rates, what is the downside of this route?
highest risk for adverse effects due to such high absorption.
T/F: most clients are NOT good at administering medications more than 2x/day
true
Can you split tablets?
ONLY if they are scored
Why should you not underdose antibiotics?
Subtherapeutic concentrations lead to the development of resistant bacteria
When should you opt for using a higher dose in a dose range for treatment of bacterial infections?
- Bacterial MIC higher
- Difficult to treat site (CNS, eye, prostate, abscess)
- Anaerobic infection
- Poorly perfused tissue that cannot be removed
In what 3 scenarios does dose precision matter and you should NOT underestimate or overestimate the dose?
Neonates
Emaciated patient
Obese patient
What is the preferred administration route for the following drugs:
A. Procaine penicillin G
B. Potassium penicillin
A. Procaine penicillin G – IM, always change needle & aspirate before admin
B. Potassium penicillin – IV, slow, watch for tachycardia (take HR before admin), and monitor for resolution of cow flop diarrhea (should not extend past 15 min after dose)
What 4 things do you base an empirical antibiotic choice on?
- your experience
- common cause of infection at that site
- which antibiotic will kill that bacteria
- being judicious (using 1st line first)
What does PROTECT ME stand for?
Prescribe only when necessary
Reduce prophylaxis
Offer other options
Treat effectively
Emply narrow spectrum
Culture appropriately
Tailor practice policy
Monitor efficacy of Abs
Educate others
State whether the following are appropriate or not:
A. clavamox for URI or community acquired pneumonia
B. urinary tract signs without performing culture to confirm infection
C. metronidazole for acute diarrhea
D. enrofloxacin ones daily dosing
E. Abs for routine dental prophylaxis
F. Abs for cough in horses
G. prophylactically in clean surgeries
H. TMS twice daily dosing
I. prolonged Ab courses
A. clavamox for URI or community acquired pneumonia – NO; doxy is better option
B. urinary tract signs without performing culture to confirm infection – NO
C. metronidazole for acute diarrhea –NO
D. enrofloxacin ones daily dosing –YES, dont do twice daily dosing
E. Abs for routine dental prophylaxis – NO
F. Abs for cough in horses -NO
G. prophylactically in clean surgeries -NO
H. TMS twice daily dosing – YES; do not do once daily dosing
I. prolonged Ab courses – NO
What 4 things must be true to necessitate SYSTEMIC Abs?
- bacterial infxn confirmed
- infxn can cause critical illness
- infxn may progress w/o tx
- condition may be life-threatening
In what 2 instances would it be appropriate to use empiric Ab therapy?
- high suspicion of bacterial infxn (pus, CBC changes, knowledge of common pathogens)
- animal showing signs of sepsis or immunosuppression
What are the 3 most common tx options for LRT disease in horses caused by streptococcus zooepidemicus?
penicillin
TMS
ceftiofur
If your culture reports a SINGLE bacterial isolate, should you employ narrow or broad spectrum Abs?
narrow
If the bacterial you culture is within a protected site, abscess, or intracellular, should the Ab you choose have a large Vd or small Vd?
Large Vd
If an infection is severe or the patient is immunocompromised which Ab type is best – bactericidal or bacteriostatic?
bactericidal
Which Abs have a SMALL Vd and are appropriate for treating infections in the plasma / ISF?
Beta-lactams
Aminoglycosides
doxycycline (lipophilic but highly protein bound)
Which Abs have a LARGE Vd and are appropriate for treating infections located in abscesses, intracellularly, or in protected sites?
Macrolides, lincosamides
phenicols
FQs
minocycline
metronidazole
Which 2 antibiotic classes are inactivated by purulent environments?
aminoglycosides
pot. sulfas
BEST to drain the fluid BEFORE using antibiotics.
Which 1st tier antibiotics are appropriate for superficial bacterial folliculitis?
Clindamycin or lincomycin
1st gen cephalosporins (cephalexin)
Amoxi-clav
TMS
T/F: if a wound is not full thickness, it is unlikely an Ab is needed
true
unless located over important structures (ex. joints), chronic, necrotic, degloving, or bite/dirty wound
what are the BEST 3 antibiotics for bite wounds?
broad spectrum because usually multiple organisms from oral cavity and NF.
clavamox (penicillin)
clindamycin (lincosamide)
doxycycline (tetracycline)
State whether antibiotic are indicated or not for the following scenarios:
A. subclinical cystitis (no symptoms)
B. CFUs <100,000 + no clinical signs
C. lower urinary tract signs in cats
A. subclinical cystitis (no symptoms) – NO
B. CFUs <100,000 + no clinical signs – NO
C. lower urinary tract signs in cats – NO
which antibiotic would you choose to treat the following:
A. uncomplicated/sporadic UTI
B. complicated/recurrent UTI
C. subclinical bactiuria
D. pyelonephritis or prostatitis
F. horses with UTI
A. uncomplicated/sporadic UTI - amoxicillin or TMS
B. complicated/recurrent UTI - c/s
C. subclinical bactiuria - none
D. pyelonephritis or prostatitis – FQ then reassess based on c/s
F. horses with UTI – TMS, ceftiofur, enro
What are 6 possible reasons for treatment failure for UTIs?
- inadeq tx time
- increase urine production (inc drug excretion)
- prolonged corticosteroid tx
- sequestration of bacteria (calculi or epithelium)
- local factors (low pH, cations in urine - Ca)
- infection isnt in the urine (pyelonephritis, prostatitis)
T/F: respiratory infections are often mixed
TRUE – they are usually aerobic and anaerobic which is why you should use broad spectrum treatment initially until you get c/s back
(ex. Beta-lactams + aminoglycoside or FQ)
What antibiotic would be necessary for mycoplasma infection of the lungs?
tetrayclines or macrolides
What would be appropriate antibiotics to treat bordetella bronchiseptica lung infection in dogs?
tetracyclines or enrofloxacin
What are the best antibiotics to use in cases of UPPER respiratory tract infections?
doxycycline
amoxicillin
what antibiotics are best for pnuemonia (LRT infection)?
doxycycline (PO) if no sepsis signs
penicillin or clindamycin + FQ (IV) if signs of sepsis
What would be the best treatment for pyothorax?
FQ + penicillin or clindamycin
LAVAGE!!!
What 4 antibiotics are appropriate for empirical tx of osteomylitis?
- injectable cephalosporins at high doses
- clindamycin high dose
- amoxi-clav
- TMS (equine)
also important to do local/regional therapy – regional limb perfusion, intraarticular inj (amikacin, ceftiofur), or lavage
which 2 antibiotics are NOT appropriate for empiric tx of osteomyelitis?
- tetracyclines
- FQs
they chelate and inactivate the drug.
When should you use antibiotics for dentals?
- you have diagnosed an infection
- there are predisposing factors – immunosuppression, underlying heart disease, or renal/hepatic disease
what bacteria are most commonly being treated in dentals?
anaerobes
what 5 drugs are good options for dentals?
- amoxi-clav
- unsayn
- clindamycin
- cefoxitin
- doxycycline / doxirobe gel
What are the best antibiotics to use in a patient with sepsis and fever?
FQ + pot. aminopenicillin
FQ + cephalosporin
in horses: aminoglycoside + b-lactam, FQ + beta lactam, or high dose ceftiofur
which antibiotics should you use to treat bacterial endocarditis (strep, staph, e.coli, erysipelothrix, corynebacterium, bartonella)?
broad spec bactericidal (unasyn + baytril) IV
What are the BEST antibiotics for hepatobiliary disease (usually e. coli, enterococcus, anaerobes)?
SA: clavamox, enrofloxacin, metronidazole
eq: TMS, enro, metro
which 4 antibiotics have the potential to be eliminated in the bile?
- chloramphenicol
- macrolides
- clindamycin
- doxycycline, minocycline
what is the treatment for histiocytic ulcerative colitis?
enrofloxacin
what drug would you use to treat giardia or clostridial infection?
metronidazole
Chronic diarrhea in middle-aged large breed dogs may respond well to which antibiotic?
Tylosin
What drug is used to treat GI disease caused by salmonella in horses?
enrofloxacin
What drug is used to treat GI disease caused by clostridium in horses?
metronidazole
what drug is used to treat Potomac horse fever?
oxytetracycline
when your patient has prostatitis, what characteristics are u looking for in an antibiotic?
unionized
lipophilic
low protein binding
dose high enough to provide a concentration gradient for diffusion.
