Choosing an Antibiotic

Question 1

In what cases might you jump to empirical second line antibiotics?

Answer 1

(When you are assuming there will be resistance, in more severe infections, and when the benefits to the patient outweigh the impact using the second line drug will have on antibiotic resistance)

Question 2

What are some things that would make you highly suspicious of a bacterial infection in your patient?

Answer 2

(The presence of pus, CBC changes, and generally knowing the disease caused by certain pathogens and your patient fits into that criteria)

Question 3

You may answer the question ‘is a systemic antibacterial necessary?’ no but still give antibiotics to particularly sick patients pending further work-up, what is the caveat to the use of those antibiotics?

Answer 3

(You stop them as soon as you have an answer that indicates bacteria is not involved, don’t just finish the course because you started it; obviously if something indicates bacterial involvement you’ll either continue if the abx works or switch if it doesn’t)

Question 4

What is empirical therapy not used for?

Answer 4

(Worst case scenarios/life threatening situations and not when resistance is a possibility for the most part)

Question 5

Drugs with small volumes of distribution should be used in what type of infections/cases?

Answer 5

(Infections located in the plasma and/or interstitial fluid such as sepsis, pneumonia, pyoderma, and UTIs)

Question 6

Drugs with large volumes of distribution should be used in what type of infections/cases?

Answer 6

(Infections located in protected sites such as CNS, eye, or prostate)

Question 7

Which of the beta lactams has the highest volume of distribution?

Answer 7

(Ampicillin)

Question 8

In what types of cases would you lean towards the use of a bactericidal antibiotic?

Answer 8

(Cases where there is immune compromise → steroid use, metabolic dz, cancer chemotherapy, neonates, geriatric patients, malnourished patients, and cases of sepsis)

Question 9

What characteristics of a superficial bacterial folliculitis case would indicate systemic antibiotics are needed over topical treatment?

Answer 9

(How extensive it is (more extensive, the more difficult it is to treat topically for the owner, might be easier to put them on a systemic) and the chronicity (more chronic = scarring/fibrosis = more difficult to treat especially topically))

Question 10

What PK/PD characteristic of a drug is most pertinent to skin and soft tissue infections?

Answer 10

(Protein binding, you want minimal protein binding so plenty of the drug can circulate through the ISF to the skin and soft tissue, don’t really care about Vd because its ISF/ECF so it could be super low Vd and it’ll work)

Question 11

What are the first tier drug choices for empirical treatment of superficial bacterial folliculitis?

Answer 11

(Clindamycin (or lincomycin), first generation cephalosporins, clavamox, and TMS if Staph pseudintermedius is suspected to be involved)

Question 12

What about a wound should be evaluated to aid in the decision to use antibiotics or not?

Answer 12

(Location (x3), cause, depth, size, and age of the wound)

Question 13

Why is metronidazole alone not a good choice for treatment of bite wounds?

Answer 13

(Bc metronidazole will get the anaerobes that will definitely be there from the bite wound but the anaerobes associated with bite wounds are very rarely cultured alone so broad spectrum abxs are needed)

Question 14

The first line drug options for sporadic UTIs are amoxicillin, clavamox, or TMS for 3-5 days, how does this change if it is a case of recurrent bacterial cystitis?

Answer 14

(At this point need a c/s, consider amoxicillin or TMS initially until c/s results back)

Question 15

(T/F) You can use drugs listed as both susceptible and intermediate for UTIs but should still avoid using drugs listed as resistant.

Answer 15

(T)

Question 16

What is the suggested duration of treatment of sporadic cystitis versus pyelonephritis?

Answer 16

(Sporadic cystitis is 3-5 days, pyelonephritis is 4-6 weeks minimum)

Question 17

Which drugs are most likely to be impacted by urine’s lower pH?

Answer 17

(Aminoglycosides and fluoroquinolones)

Question 18

Which drugs are most likely to be impacted by urine containing cations (such as calcium)?

Answer 18

(Tetracyclines and fluoroquinolones)

Question 19

You want your drug of choice for a prostate infection to be unionized/ionized (choose), hydrophilic/lipophilic (choose), and low/high (choose) protein bound.

Answer 19

(Unionized, lipophilic, and low protein binding, need to dose high enough to provide a concentration gradient for diffusion and something weakly basic would be nice because will be trapped in the prostate d/t lower pH)

Question 20

(T/F) There are relatively few barriers to drug penetration into the lungs.

Answer 20

(T but there are exceptions such as non-fenestrated capillaries in the alveoli, abscesses, and consolidated/poorly perfused lung)

Question 21

Respiratory infections are typically aerobic/anaerobic/mixed (choose).

Answer 21

(Mixed = broad spectrum coverage required initially)

Question 22

You are already treating a respiratory tract infection with clavamox, what would you add if you cultured Mycoplasma?

Answer 22

(Either a tetracycline or a macrolide)

Question 23

What bacteria do you have to make sure you are covering when treating respiratory infections in horses?

Answer 23

(Strep zooepidemicus)

Question 24

Bone and joint infections are not particularly difficult to treat because those spaces are just an extension of the extracellular fluid which most (if not all) abx can reach, what are some exceptions that may prove more difficult to treat?

Answer 24

(Joint infections with excessive purulent debris (will inactivate drugs), bone sequestra (its devitalized so no blood flow = no abx), and surgical implants bc biofilms)

Question 25

What are some of the drugs used to empirically treat osteomyelitis?

Answer 25

(Injectable cephalosporins, high dose clindamycin, clavamox, TMS, and fluoroquinolones (but FQs chelated by calcium so use is debatable))

Question 26

(T/F) Tetracyclines reach high concentrations in bone and are therefore great for treating osteomyelitis.

Answer 26

(F, reach high concentrations because it is chelating to all the calcium and potentially becoming inactive (there were a ton of ?s beside this point on the ppt))

Question 27

What are the drug combos typically used for cases of sepsis in small animal patients?

Answer 27

(Fluoroquinolone + potentiated aminopenicillin or fluoroquinolone + cephalosporin)

Question 28

What are the drug combos/options typically used for cases of sepsis in horses?

Answer 28

(Aminoglycoside + beta-lactam, fluoroquinolone + beta-lactam, or high dose ceftiofur)

Question 29

What are the most common bacteria associated with bacterial endocarditis?

Answer 29

(Staphs, streps, and E. coli; others are Erysipelothrix, Corynebacteria, Bartonella, and many others including anaerobes)

Question 30

What GI dzs is metronidazole good for treating in small animals?

Answer 30

(Giardia and Clostridial dzs (good for this in horses too))

Question 31

What GI dz is oxytetracycline good for treating in horses?

Answer 31

(Potomac horse fever)

Question 32

What is a good treatment timeline for pyoderma in a dog?

Answer 32

(Tx for 2-3 weeks, tell owner should be significantly better in 1-2 weeks, recheck at 2-3 week point and extend or discontinue as needed)

Question 33

What are some things you can do to minimize ceftiofur injection site reactions?

Answer 33

(Use a 16 G 1.5 inch needle, administer into a large muscle (cervical, semimem, semitend), do not administer more than 10 ml per site, and draw up drug with one needle/adm with another needle/switch needles when you switch sites)