Choosing an Antibiotic Flashcards
In what cases might you jump to empirical second line antibiotics?
(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)
What are some things that would make you highly suspicious of a bacterial infection in your patient?
(The presence of pus, CBC changes, and generally knowing the disease caused by certain pathogens and your patient fits into that criteria)
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?
(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)
What is empirical therapy not used for?
(Worst case scenarios/life threatening situations and not when resistance is a possibility for the most part)
Drugs with small volumes of distribution should be used in what type of infections/cases?
(Infections located in the plasma and/or interstitial fluid such as sepsis, pneumonia, pyoderma, and UTIs)
Drugs with large volumes of distribution should be used in what type of infections/cases?
(Infections located in protected sites such as CNS, eye, or prostate)
Which of the beta lactams has the highest volume of distribution?
(Ampicillin)
In what types of cases would you lean towards the use of a bactericidal antibiotic?
(Cases where there is immune compromise → steroid use, metabolic dz, cancer chemotherapy, neonates, geriatric patients, malnourished patients, and cases of sepsis)
What characteristics of a superficial bacterial folliculitis case would indicate systemic antibiotics are needed over topical treatment?
(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))
What PK/PD characteristic of a drug is most pertinent to skin and soft tissue infections?
(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)
What are the first tier drug choices for empirical treatment of superficial bacterial folliculitis?
(Clindamycin (or lincomycin), first generation cephalosporins, clavamox, and TMS if Staph pseudintermedius is suspected to be involved)
What about a wound should be evaluated to aid in the decision to use antibiotics or not?
(Location (x3), cause, depth, size, and age of the wound)
Why is metronidazole alone not a good choice for treatment of bite wounds?
(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)
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?
(At this point need a c/s, consider amoxicillin or TMS initially until c/s results back)
(T/F) You can use drugs listed as both susceptible and intermediate for UTIs but should still avoid using drugs listed as resistant.
(T)
What is the suggested duration of treatment of sporadic cystitis versus pyelonephritis?
(Sporadic cystitis is 3-5 days, pyelonephritis is 4-6 weeks minimum)
Which drugs are most likely to be impacted by urine’s lower pH?
(Aminoglycosides and fluoroquinolones)
Which drugs are most likely to be impacted by urine containing cations (such as calcium)?
(Tetracyclines and fluoroquinolones)
You want your drug of choice for a prostate infection to be unionized/ionized (choose), hydrophilic/lipophilic (choose), and low/high (choose) protein bound.
(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)
(T/F) There are relatively few barriers to drug penetration into the lungs.
(T but there are exceptions such as non-fenestrated capillaries in the alveoli, abscesses, and consolidated/poorly perfused lung)
Respiratory infections are typically aerobic/anaerobic/mixed (choose).
(Mixed = broad spectrum coverage required initially)
You are already treating a respiratory tract infection with clavamox, what would you add if you cultured Mycoplasma?
(Either a tetracycline or a macrolide)
What bacteria do you have to make sure you are covering when treating respiratory infections in horses?
(Strep zooepidemicus)
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?
(Joint infections with excessive purulent debris (will inactivate drugs), bone sequestra (its devitalized so no blood flow = no abx), and surgical implants bc biofilms)
