Empiric Antibiotic Selection

Question 1

What do we mean by empiric antibiotic therapy?

Answer 1

Choosing an antibiotic based on experience

Question 2

What are the two major questions you must ask yourself when empirically treating an infection?

Answer 2

Which bacteria most commonly causes infection at this site?

What antibiotic will treat those bacteria at that site?

Question 3

T/F: In general, 1st line antibiotics aren’t that important to human medicine

Answer 3

True

Question 4

When should we pursue first line treatment?

Answer 4

Common, non-life-threatening infections

Question 5

Prior to using second line antibiotics, it is recommended to _________

Answer 5

Submit culture and sensitivity

Question 6

A lil kitten at the shelter is brought to the clinic for conjunctivitis, congestion, and sneezing. Does this kitty need antibiotics?

Answer 6

Probably not - likely viral

Question 7

A 5yo MC dog presents to your clinic with acute diarrhea. Does this patient need antibiotics?

Answer 7

Probably not

Question 8

Antibiotics are commonly used inappropriately in horses. What are some examples of overprescription in horses?

Answer 8

Treatment of cough - consider asthma

Wounds over non-vital structures (ex. Wound over the flank compared to a wound over the pastern)

Only administering TMS once daily when it should be twice

Question 9

A dog has a dry, harsh, hacking cough that developed after a week in a kennel. The patient is otherwise normal. Does this patient need antibiotics?

Answer 9

Not at this time - highly suspicious of bordetella, which is often a self-limiting disease

Question 10

What clinical criteria might you use to decide to treat with antibiotics?

Answer 10

Fever, anorexia, lethargy
Purulent discharge
Cytology
Duration of CS >10d
Worsening CS

Question 11

Infections like sepsis, pneumonia, pyoderma, and UTIs often require drugs with a _________ Vd as the infection is located in the ___________.

Answer 11

Small; plasma ISF

Question 12

What locations of bacterial infections would require an antibiotic with a wide volume of distribution?

Answer 12

Eye
CNS
Prostate

Question 13

Name some drugs with a wide volume of distribution

Answer 13

Macrolides
Lincosamides
Chloramphenicol
Fluoroquinolones
Tetracyclines
Metronidazole

Question 14

Discuss of immune status would affect which antibiotic you choose

Answer 14

Immunocompromised patients are often in need of bactericidal, broad-spectrum antibiotics

Question 15

T/F: Systemic antibiotics are always indicated in cases of superficial bacterial folliculitis (SBF)

Answer 15

False - must take severity, chronicity, and underlying cause into consideration when treating cases of SBF

Question 16

Instead of using systemic antibiotics for SBF, you should consider __________

Answer 16

Topicals

Question 17

Name some commonly used drugs for skin and ST infections (remember, this location is connected to ECF)

Answer 17

Amoxicillin (+clav)
Ampicillin
TMS
Enrofloxacin
Cefovecin

Question 18

T/F: Once you prescribe a patient with SBF antibiotics, you can expect the infection to heal in about 7 days without reoccurrence.

Answer 18

False - always look for underlying conditions

If this patient has allergies, a metabolic condition, or is immunocompromised, the infection is likely to recur unless the primary cause is addressed.

Question 19

When treating a bite wound, what kind of bacteria should we suspect might be involved?

Answer 19

Anaerobes - can treat with doxycycline, clindamycin, or clavamox

Question 20

What are the three kinds of urinary tract “infections”?

Answer 20

Subclinical cystitis

Uncomplicated, sporadic, simple cystitis

Recurrent bacterial cystitis (3 or more episodes in a 12 month period)

Question 21

What can we sometimes use drugs with intermediate sensitivities to treat UTIs?

Answer 21

A lot of drugs concentrate in the urine

Do NOT use drugs listed as resistant on C&S

Question 22

What are some reasons that treatments for a UTI could fail?

Answer 22

Inappropriate duration

Calculi or epithelial tissue harboring bacteria

Increased urine production (administer drugs at night)

Prolonged corticosteroid therapy

Local factors affecting antibiotic efficacy

Infection isn’t in the urine, but might be in the kidney or prostate

Question 23

What characteristics would you like to see in a drug for treatment of prostatitis?

Answer 23

Low protein binding
Unionized
Lipophilic
Doses high enough to provide a concentration gradient for diffusion

Side note: using basic drugs could lead to ion trapping in the prostate, which would increase prostatic concentrations

Question 24

T/F: the lungs are difficult to penetrate with antibiotics and often require advanced techniques for delivery

Answer 24

False - Relatively few barriers to drug penetration into the lung

Question 25

What types of infections are common in the respiratory tract?

Answer 25

Mixed! - Aerobic and anaerobic bacteria are likely, so start with broad spectrum treatment

Question 26

What two drugs are commonly used for empiric antibiotic therapy for RTIs until C&S results are available?

Answer 26

Beta-lactams and aminoglycosides/FQs

Question 27

Bones and joints are an extension of the _____

Answer 27

ECF!

Question 28

Overall, joints and bones aren’t hard to reach with antibiotics; however, there are some exceptions, can you name some?

Answer 28

Joints with excessive purulent debirs
Sequestration
Implants and biofilms

Question 29

Discuss the relationship between tetracyclines and bone

Answer 29

Tetracyclines are chelated by calcium, basically becoming stuck in the bone. There is a question of whether this inactivates the drug and contributes to therapeutic failure.

Question 30

T/F: because transient bacteremia is likely during dental procedures, providing prophylaxis is almost always indicated

Answer 30

False - we really only use antibiotics for dental disease when there is a severe infection, the patient is immunosuppressed, the patient has underlying heart or renal/hepatic disease

Question 31

What kind of bacteria are commonly found in the mouth?

Answer 31

Anaerobes

Question 32

For a septic patient, what kind of antibiotic therapy should you initiate?

Answer 32

Broad-spectrum

Often use combination therapy of FQ and potentiated amino penicillin or cephalosporin

Question 33

What bacteria are commonly involved in cases of bacterial endocarditis? What should we do to figure out who is involved?

Answer 33

Staphs, streps, E. coli
Erysipelothrix
Corynebacteria
Bartonella
Anaerobes like bacterioides

Culture the blood!

Question 34

What kind of antibiotic should you use for empiric therapy of bacterial endocarditis?

Answer 34

Bactericidal
IV

Most cases utilize penicillin/BLI and FQ

Question 35

What drugs are commonly used to treat hepatobiliary disease in dogs and cats? Horses?

Answer 35

Dogs & Cats - Clavamox, Enro, Metro

Horses - TMS, Enro, Metro

Question 36

_____________ is used to treat histiocytic ulcerative colitis in boxers

Answer 36

Enrofloxacin

Question 37

A client brings their 2yo MC Great Pyrenees (outdoor, working dog) into the clinic for itchy, gross skin (pustules, papules, and crusted lesions).

The patient is not on any preventatives, so you suspect this might the result of a flea infestation. What can you do for this dog?

Answer 37

Find the fleas and get started on preventatives!

Because the patient is showing signs of a skin infection, we can empirically treat.

We can suggest topicals, but if the owner cannot bathe the dog 3x per week (which sounds like she can’t b/c outdoor and working, we can use first line antibiotics like clavamox, clindamycin, and cephalexin.