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SpanishEvaluation of a Rapid Immunoassay for Point-of-Care Detection of Bacteria in Cat Urine
Dr. Byron is an Associate Professor in Small Animal Internal Medicine at The Ohio State University. She received her DVM from OSU in 1998, completed a rotating internship at VCA West Los Angeles Animal Hospital, and completed her residency in Internal Medicine at OSU in 2004.
She was a faculty member at University of Illinois College of Veterinary Medicine for 6 years and joined OSU’s faculty in 2011. Her Master’s research involved diagnosis and treatment of urinary incontinence, and she continues to be active in the field of urology and nephrology today.
She has received a number of teaching honors, including the Norden/Pfizer Teaching Excellence Award in 2011 and The Dean’s Award for Creativity in Teaching in 2015.
Abstract
Lower urinary tract signs in cats (LUTS) are more frequently due to sterile
inflammation rather than infection. Practitioners may forgo microbiological
culture due to cost, and prescribe antimicrobial agents empirically,
incurring unnecessary selection pressure and side effects on most patients.
Therefore, a rapid screening test for detection of bacteria in cat urine could
direct appropriate therapy.
A “dip-stick” style immunoassay to detect bacteria was performed on
feline urine (n = 100) submitted for routine bacterial culture in a Veterinary
Teaching Hospital. The immunoassay was performed according to
manufacturer instructions and culture was performed quantitatively on
Columbia agar with 5% sheep’s blood, with a maximum 72 hour incubation
time at 35˚C in ambient air. Bacteria were identified using matrix-assisted
laser-desorption time-of-flight mass spectrometry.
Eleven samples yielded ≥ 100,000 cfu/ml in culture, ten of which
(90.9%) were positive on the immunoassay, and consisted of E. coli (n
= 5), Enterococcus spp. (n = 5), and Staphylococcus felis (n = 1). Three
samples yielded ≤ 200 cfu/ml, one of which (33.3%) was positive on the
immunoassay, and consisted of E. coli (n = 2), and Staphylococcus felis + E.
coli (n = 1). The immunoassay was positive for two (2.3%) culture negative
samples. The immunoassay correctly categorized the bacteria as gram-negative
or gram-positive for eleven (100%) of the concordant samples.
When samples with ≤ 1000 cfu/ml were considered negative, sensitivity
and specificity of the immunoassay were 90.9% and 96.6% respectively,
with positive and negative predictive values of 76.9% and 98.9%. Given
the low prevalence of bacterial cystitis in cats, these data suggest that the
immunoassay is a useful screening tool for cats presenting with LUTS.