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ABSTRACT: Background
To characterize urinary isolates, the Clinical and Laboratory Standards Institute (CLSI) uses an amoxicillin breakpoint for cats based on plasma (not urine) drug concentrations (?0.25??g/mL), but a urine-specific breakpoint for dogs exists (?8??g/mL).Objectives
To measure urine concentrations of amoxicillin and clavulanate after PO administration of amoxicillin-clavulanate to cats, and to suggest updated urine-specific susceptibility breakpoints for PO amoxicillin and amoxicillin-clavulanate in cats.Animals
Eleven healthy purpose-bred cats.Methods
Cats were given 3 62.5?mg doses of amoxicillin-clavulanate PO q12h. After the third dose, urine was collected over 28?hours, recording urination time and volume. At least 3 urine samples were collected per cat. Liquid chromatography with mass spectrometry was used to determine the urine concentrations of amoxicillin and clavulanate.Results
Amoxicillin concentrations were >8??g/mL in all urine samples collected within 12?hours after administration (range, 31.6-1351??g/mL), with means of 929??g/mL (0-6?hours) and 532??g/mL (6-12?hours). The mean half-life of amoxicillin in urine was 1.99?hours, and mean recovery was 30%. Clavulanate was detected in all urine samples, with mean half-life of 2.17?hours.Conclusions and clinical importance
Orally administered amoxicillin-clavulanate resulted in urine amoxicillin concentrations above the cutoff (8??g/mL) for wild-type Escherichia coli in all cats. Because urine-specific susceptibility testing breakpoints can be determined using urine concentrations, this information should allow new CLSI uropathogen susceptibility breakpoints for amoxicillin and amoxicillin-clavulanate in healthy cats, increasing the urine breakpoint from ?0.25 to ?8??g/mL.
SUBMITTER: KuKanich K
PROVIDER: S-EPMC7848311 | biostudies-literature | 2020 Dec
REPOSITORIES: biostudies-literature
KuKanich Kate K Woodruff Kallie K Bieberly Zackery Z Papich Mark G MG KuKanich Butch B
Journal of veterinary internal medicine 20201206 1
<h4>Background</h4>To characterize urinary isolates, the Clinical and Laboratory Standards Institute (CLSI) uses an amoxicillin breakpoint for cats based on plasma (not urine) drug concentrations (≤0.25 μg/mL), but a urine-specific breakpoint for dogs exists (≤8 μg/mL).<h4>Objectives</h4>To measure urine concentrations of amoxicillin and clavulanate after PO administration of amoxicillin-clavulanate to cats, and to suggest updated urine-specific susceptibility breakpoints for PO amoxicillin and ...[more]