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128 Urinary Tract Infections 1193

Recommendations from this committee are considered extended‐release cephalosporins (e.g., cefovecin). Second‐
VetBooks.ir the gold standard for breakpoint determination. Veterinary tier antibiotics are not recommended as a first‐line treat-
ment for an uncomplicated UTI, without appropriate
laboratories (or human laboratories with appropriate
susceptibility panels for commonly used veterinary anti-
considered when rapid treatment is necessary to return
biotics) that follow CLSI guidelines should be used for culture and sensitivity results. However, these may be
culture and sensitivity testing. to function, prevent systemic spread of bacteria, or when
Depending on the laboratory, comparing antibiotics penetration into a specific tissue, such as the prostate, is
with similar susceptibility (e.g., cephalexin and cefazolin) needed. For penetration into prostatic tissue, antibiotics
may be necessary but requires making assumptions. For should be lipid soluble, not highly protein bound, and
example, when comparing cefazolin with cephalexin, ionize at the pH of the prostatic tissue. Good prostate
cefazolin is typically administered intravenously q6h gland penetration can usually be achieved with fluoro-
whereas cephalexin is typically administered orally quinolones, trimethoprim‐sulfa, and chloramphenicol.
q8–12h. It is also important to remember that in vitro
culture and sensitivity results may not correlate with in Uncomplicated UTI
vivo efficacy. For example, regardless of the susceptibility
results for Enterococcus, certain antibiotics including Dogs and cats with uncomplicated are typically treated
cephalosporins, trimethoprim‐sulfamethoxazole, clin- with a 7–14‐day course of antibiotics. It is reasonable to
damycin, and aminoglycosides should always be consid- assume that shorter durations of appropriate antibiotics
ered resistant since they are not effective clinically and (≤7 days) may be effective but clinical trials are needed to
do not correlate with in vitro results. further evaluate shorter duration treatments. It is always
In many cases, antibiotic sensitivity testing results pro- ideal to treat on the basis of urine culture and sensitivity
vide a clear direction for treatment with an antibiotic results, although economic constraints may preclude this
that is orally administered, has few potential adverse in first‐time patients with suspected uncomplicated UTI.
effects, and reasonable cost. In some cases, sensitivity In these cases, antimicrobial selection should be based on
results demonstrate a high degree of bacterial resistance, bacterial characteristics observed in the urine sediment
and route of administration, high cost, or potential (e.g., gram positive vs gram negative, cocci vs rods).
adverse effects of the potentially effective antibiotic may For example, if a gram‐negative rod or bacillus is seen
be a concern. Although MIC may be used as a guideline (e.g., E. coli, Enterobacter, Klebsiella, Proteus), cepalospor-
for antibiotic selection, veterinary breakpoints for most ins would be a good option. With gram‐positive cocci
antibiotics in the urinary tract of dogs and cats have (e.g., Staphylococcus, Streptococcus, Enterococcus), amoxi-
not been determined. When intermediate results are cillin and cephalosporin would be options. Clinical signs
obtained, it may be possible to achieve a cure if no alter- should resolve within 48 hours with appropriate treat-
native antimicrobial exists. This would most likely be ment. Along with resolution of clinical signs, evidence of
achieved by using a higher dose of an antimicrobial that inflammation in urine sediment should also resolve in 3–5
is excreted in the urine. In resistant infections, request- days of antibiotic treatment.
ing an expanded antimicrobial sensitivity profile (e.g., When empiric antibiotic treatment is used, instruc-
ceftazedime, carbenicillin) may suggest alternative treat- tions to owners regarding what to expect as well as fol-
ment regimes. Most commercial bacteriology laborato- low‐up plans are critical. If presenting clinical signs do
ries have a second and third tier of antibiotics for not resolve quickly, owners should be aware of the need
expanded sensitivity testing; however, high cost and par- for a follow‐up urinalysis and culture and sensitivity.
enteral administration may be trade‐offs. Owners should also be aware of the importance of com-
Inappropriate antibiotic dosages or unnecessary usage pleting the entire antibiotic regime, even if signs resolve
can lead to resistant organisms, affecting not only the early in the course of treatment. Finally, owners should
individual patient but potentially bacterial resistance in be instructed to observe their pets closely for signs of
other veterinary patients and owners. Antimicrobials UTI recurrence after the treatment regime is complete.
that are excreted in the urine are the mainstay of UTI Clear communication and understanding of the “game
treatment and initial antibiotic considerations should plan” will result in improved treatment outcome and
include amoxicillin, cephalexin or trimethoprim‐sulfadi- increased client willingness to return in cases of empiric
azine. When host defense mechanisms are compro- treatment failures.
mised, previous or current sensitivity results indicate
potential resistance, or when the infection involves the Short‐Course/High‐Dose Protocol
prostate or kidneys, second tier antibiotic choices Due to concerns with owner compliance during longer
should be considered including potentiated beta‐lactams treatment protocols, short‐course/high‐dose protocols
(e.g., amoxicillin‐clavulanic acid), fluoroquinolones, or have been proposed for the treatment of uncomplicated