Evaluation of a catalase-based urine test for the detection of urinary tract infection in dogs and cats

Evaluation of a rapid immunoassay for bacteriuria in dogs

BACKGROUND

The ability to detect bacteriuria in dogs with a point-of-care test might improve medical care and antimicrobial stewardship.

HYPOTHESIS AND OBJECTIVE

A rapid immunoassay (RIA; RapidBac) will provide acceptable sensitivity and specificity for diagnosis of bacteriuria.

ANIMALS

Forty-four client-owned dogs with a clinical indication for urinalysis and aerobic bacterial urine culture.

METHODS

Prospective study. Urine, collected by cystocentesis, was submitted for urinalysis and culture at a diagnostic laboratory. Owners completed an enrollment questionnaire regarding their dogs' clinical signs. The RIA was performed according to the manufacturer's guidelines. Results were compared to culture.

RESULTS

Forty-four urine specimens were evaluated from 44 dogs. The sensitivity and specificity of the RIA test to detect bacteriuria compared to urine culture were 81.8% (95% CI, 65.7%-97.9%) and 95.5% (95% CI, 86.8%-99.9%), respectively. For cultures yielding ≥10³  CFU/mL, sensitivity increased to 90.0% (95% CI, 76.9%-100%) and specificity was similar at 95.2% (95% CI, 86.1%-99.9%). Malodorous urine, bacteriuria, and pyuria were more likely to be present in dogs with positive RIA or urine culture results compared to dogs with negative results.

CONCLUSIONS AND CLINICAL IMPORTANCE

The RIA was easy to perform and had good sensitivity and excellent specificity in this group of dogs. The RIA might be a useful screening test for decision-making regarding antimicrobial therapy in dogs with a clinical indication for urine culture. Consideration could be given to amending the International Society for Companion Animal Infectious Disease definition of bacterial cystitis as the presence of signs of lower urinary tract disease together with positive culture or a positive RIA.

Comparison of a Chromogenic Urine Culture Plate System (UTid+) and Conventional Urine Culture for Canine and Feline Specimens

In companion animal medicine, urinary tract infection (UTI) is one of the most common indications for antimicrobial therapy. Definitive diagnosis of UTI requires isolation of bacteria with routine urine culture from an animal with concurrent clinical signs. Urine culture is typically performed at reference laboratories where paired susceptibility testing can be performed, but delays in shipment or processing can affect results. This study evaluated the use of a selective chromogenic, point-of-care culture system (UTid+) compared to conventional urine culture. A total of 119 (73 canine and 46 feline) cystocentesis urine samples were evaluated. Conventional urine culture was positive for 28 (23.5%) of the 119 cultures and UTid+ culture was positive for 26 (21.8%). The overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 92.3%, 97.8%, 92.3%, 97.8 and 96.6% for UTid+ respectively. Overall, the UTid+ culture system showed an acceptable level of accuracy when compared to conventional urine culture. Agreement of identification results was high (κ = 0.90) with an important exception being Proteus spp. which was only identified in 1/3 positive cultures. UTid+ may be useful in scenarios where a common UTI pathogen is expected and identification within 24 h is ideal; however, conventional urine culture remains the gold standard.

Development of a method for creating antibiograms for use in companion animal private practices

OBJECTIVE

To identify a method for developing antibiograms for use in companion animal private practices (PPs).

SAMPLES

Reports (n = 532) of aerobic bacterial culture and antimicrobial susceptibility testing performed between January 1, 2018, and December 31, 2018, at 11 PPs and 1 academic primary care practice (APCP).

PROCEDURES

Data extracted from reports included patient identification number, laboratory accession number, patient signalment, collection method, body site, and results of bacterial culture and antimicrobial susceptibility testing. A custom antibiogram was then constructed with the help of commonly available software by adapting methods used by human hospitals. Susceptibility patterns of bacteria isolated by PPs and the APCP were compared to identify challenges associated with collating data from multiple laboratories.

RESULTS

4 bacterial species (Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, and Staphylococcus pseudintermedius) and 3 bacterial groups (Enterobacteriaceae, Enterococcus spp, and coagulase-positive Staphylococcus spp) met the minimum requirement of ≥ 15 isolates for construction of an antibiogram. For urine samples, 3 bacterial species and 2 bacterial groups met the minimum requirement of ≥ 10 isolates. For samples from skin, 2 bacterial species and 2 bacterial groups met the minimum requirement of ≥ 10 isolates. Patient signalment, sample source, and distribution of bacterial isolates were similar between PP and APCP patients.

CONCLUSIONS AND CLINICAL RELEVANCE

Results demonstrated that it was feasible to adapt existing guidelines for developing antibiograms in human medicine to the veterinary outpatient setting. Use of antibiograms could aid in empirical antimicrobial drug selection in a manner that supports antimicrobial stewardship principles.

Diagnostic accuracy of a point-of-care test using voided urine samples for detection of bacteriuria in dogs with signs of lower urinary tract disease

BACKGROUND

Bacterial urine culture is recommended in dogs suspected of having urinary tract infection (UTI), but there is expense and delay in obtaining such results.

HYPOTHESIS/OBJECTIVE

To determine the diagnostic performance of a rapid immunoassay (RIA) dipstick for detection of bacteriuria using voided urine from dogs with clinical signs of lower UTI.

ANIMALS

Twenty-four client-owned dogs.

METHODS

Voided urine was collected and the RIA performed within 30 minutes. Urine collected by cystocentesis was submitted for aerobic urine culture. McNemar's test and kappa coefficient were calculated to determine agreement between the 2 tests.

RESULTS

Nine of 21 dogs (43%) had UTI verified by aerobic urine culture. There was 1 false-negative and no false-positive RIA results. Sensitivity, specificity, positive predictive value, and negative predictive value of the RIA were 89%, 100%, 100%, and 92%, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

This RIA is promising for correctly identifying whether or not voided urine samples from dogs with lower urinary tract clinical signs have true bacteriuria in a rapid, inexpensive manner. Additional patients should be enrolled in a similar study to determine if diagnostic performance is robust in a large population.

Urinary Tract Infection

"Urinary tract infection (UTI) is a common diagnosis in companion animal practice and is responsible for a significant proportion of antimicrobial use in veterinary medicine. The veterinary community has begun to follow the standards of care in human medicine and shift its definition of an UTI based on culture results and toward the presence of lower urinary tract symptoms. An improved understanding of the pathophysiology of UTI, risk factors for clinical disease, and the implementation of more reliable in-house diagnostic testing can lead to improved outcomes for patients and reduce inappropriate treatment. Investigation of antibiotic-sparing therapies holds some promise as well."

Subclinical bacteriuria in cats: prevalence, findings on contemporaneous urinalyses and clinical risk factors

Objectives Subclinical bacteriuria (SB) is bacterial colonization of the urinary tract in the absence of clinical signs. The purposes of this study were to determine the prevalence of SB in cats and to describe results of the contemporaneous urinalysis. Secondarily, patient characteristics associated with SB were compared with those for cats without SB. Methods An electronic search identified all urine cultures performed on cats at a teaching hospital between 2009 and 2015. Results were subcategorized based on the presence or absence of lower urinary tract disease (LUTD) and SB-positive cases identified. The first control population was from samples without LUTD. The second control population was from all samples not identified as a SB-positive sample, including subclinical negative samples and those with LUTD. Five controls for each SB-positive sample were selected for both control groups. Medical records for all groups were reviewed. Results In all, 31/500 (6.2%) subclinical samples were positive. Most infections were a single organism (n = 27); four contained multiple organisms. Escherichia coli was the most common species (58%) followed by Enterococcus species (25%). Positive specimens were more likely to be from female cats (n = 24) vs male (n = 7; P = 0.0054). SB was strongly associated with bacteriuria (60% vs 6%; P <0.0001) and pyuria (67% vs 19%; P <0.0001). Positive specimens were significantly more likely to have an abnormal sediment examination (odds ratio 13.5, P <0.0001). When compared with all specimens including those with LUTD, SB was significantly associated with a lower urine specific gravity (1.022 vs 1.030; P = 0.0256) and presence of chronic kidney disease (68% vs 46%; P = 0.0168). Conclusions and relevance In this study, SB appears to be uncommon in cats and, in most cases, is associated with an abnormal urine sediment examination. Based on this study, there is little indication to perform a culture in a cat with no clinical signs of LUTD and an unremarkable sediment examination.

Diagnostic accuracy of a rapid immunoassay for point of-care detection of urinary tract infection in dogs

OBJECTIVE

To determine the diagnostic accuracy of a rapid immunoassay (RIA) for point-of-care detection of urinary tract infection (UTI) of dogs, compared with criterion-referenced diagnosis with bacterial culture.

SAMPLE

200 urine samples obtained from dogs and submitted to a veterinary microbiology diagnostic laboratory for routine bacterial culture and antimicrobial susceptibility determination.

PROCEDURES

Samples were evaluated by use of quantitative bacterial culture and the RIA. Sensitivity, specificity, and positive and negative predictive values of the RIA were calculated; results of bacterial culture were the criterion-referenced outcome. A κ statistic was calculated to determine agreement between bacterial culture and RIA results.

RESULTS

56 of 200 (28%) urine samples had positive results for bacterial growth by use of culture methods; there were 38 (19%) positive results likely to be associated with bacterial UTI on the basis of sample collection method and bacterial concentration. Sensitivity and specificity of the RIA for detecting samples likely to be associated with UTI (≥ 1,000 CFUs/mL) were 97.4% and 98.8%, respectively. The positive and negative predictive values of the RIA for bacterial cultures with likely UTI were 0.949 and 0.994, respectively. Agreement between bacterial culture and RIA outcome for UTI was substantial (weighted κ, 0.718).

CONCLUSIONS AND CLINICAL RELEVANCE

The RIA test evaluated in this study accurately detected UTI of dogs, compared with detection with the criterion-referenced bacterial culture method. Use of this point-of-care RIA could allow clinicians to diagnose UTI at the time of a patient visit and provide information useful for immediately initiating empirical antimicrobial treatment.