Frequency and risk factors for urinary tract infection in cats with diabetes mellitus

BACKGROUND: Identification and control of infections are important in the management of diabetic cats. Urinary tract infections have not been well characterized in diabetic cats. This retrospective study was performed to review and characterize urinary tract infections in diabetic cats. HYPOTHESIS: Urinary tract infections are common in diabetic cats. ANIMALS: A review was made of the medical records of 141 diabetic cats that had had urine obtained for culture by antepubic cystocentesis and that had not been treated with antibiotics, undergone urinary tract catheterization or urinary tract surgery within 2 weeks of urine collection or had urethral obstruction at the time of urine collection. METHODS: A review of medical records. RESULTS: Urinary tract infection was identified in 18 of 141 diabetic cats. Escherichia coli was the most common isolate (67%). Female cats were at increased risk (prevalence odds ratios [POR], 3.7; 95% confidence interval [CI], 1.3 to 10.2; P = .013). Clinical signs of lower urinary tract disease and findings on urine sediment examination were good predictors of positive urine cultures. CONCLUSIONS AND CLINICAL IMPORTANCE: Urinary tract infections are common in diabetic cats regardless of status of diabetic control, suggesting routine monitoring with urine sediment exams or urine culture is warranted.     

Clinical features and risk factors for development of urinary tract infections in cats

The clinical and diagnostic features of 155 cats with urinary tract infection (UTI) and 186 controls with negative urine culture/s were characterized retrospectively (signalment, clinical signs, urinalysis, urine culture, concurrent diseases, lower urinary tract diagnostic/therapeutic procedures). Multivariable logistic regression was used to identify risk factors associated with UTI. Cats of all ages were affected by UTI with no sex/breed predisposition. Lower urinary tract signs were absent in 35.5% of cats with UTI. Pyuria and bacteriuria had sensitivities of 52.9% and 72.9%, and specificities of 85.5% and 67.7% for detection of UTI, respectively. Risk factors significantly associated with increased odds of UTI were urinary incontinence [odds ratio (OR) = 10.78, P = 0.0331], transurethral procedures (OR = 8.37, P <0.0001), urogenital surgery (OR = 6.03, P = 0.0385), gastrointestinal disease (OR = 2.62, P = 0.0331), decreased body weight (OR = 0.81, P = 0.0259) and decreased urine specific gravity (OR = 0.78, P = 0.0055). Whilst not independently significant, renal disease and lower urinary tract anatomic abnormalities improved statistical model performance and contributed to UTI.     

Effects of urinary tract inflammation and sample blood contamination on urine albumin and total protein concentrations in canine urine samples

BACKGROUND: Urinary tract inflammation and hemorrhage are believed to be common causes of proteinuria in dogs based on results of studies that measured total urine protein concentration. A method to quantify urine albumin (UAlb) concentration in dogs recently has become available; however, the effect of inflammation on albuminuria is unknown. OBJECTIVES: The goals of this study were to determine the effects of urinary tract inflammation, as indicated by pyuria and sample blood contamination, on UAlb concentration and on urine protein:creatinine (UPC) ratio in dogs. METHODS: Urine samples were obtained from dogs with pyuria that were presented to a veterinary teaching hospital or were part of a laboratory colony. To mimic the effects of hematuria, canine whole blood was added to a microscopically normal canine urine sample that had baseline albumin and total protein concentrations below the limits of detection. UAlb concentration was measured using a canine albumin-specific competitive ELISA. UPC ratio was determined using routine methods. RESULTS: Of 70 samples with pyuria, 67% had negligible UAlb concentrations and 81% had normal UPC ratios. UAlb concentration but not UPC ratio was significantly higher (P < 0.05) in samples with concurrent hematuria or bacteriuria. When whole blood was added to normal urine, UAlb concentration did not exceed 1 mg/dL until the sample became visibly pink; the UPC did not exceed 0.4 at any dilution. CONCLUSIONS: Many dogs with pyuria do not have albuminuria or proteinuria; however, albuminuria may be more likely in dogs with pyuria and concurrent hematuria or bacteriuria. Hematuria may not cause an increase in UAlb concentration until it becomes macroscopic and even then may not increase the UPC ratio.     

Cystocentesis is essential for reliable diagnosis of urinary tract infections in cats

Urine samples were taken from 79 cats with clinical signs of acute feline lower urinary tract disease (FLUTD) by means of cystocenthesis, catheterization, or at voiding and were cultured. No bacteria were cultured from 79% of the samples taken by cystocenthesis, 55% of the samples obtained by catheterization, and 17% of the samples obtained at voiding. Samples obtained by cystocenthesis most often yielded pure cultures, whereas the voided samples were often contaminated, yielding mixed cultures. Therefore, it is difficult to interpret culture results for voided or catheterized urine samples, which may lead to overdiagnosis of urinary tract infections. E. coli was the most prevalent bacterial species. Numbers of bacteria were low (10(2) to 10(3)/ml) in three out of eight culture-positive samples taken by cystocenthesis, indicating that the number of bacteria present in the bladder of cats with urinary tract infections may be low. This may lead to underdiagnosis of urinary tract infections when interpreting culture results for voided and catheterized samples, because bacterial counts lower than 10(3) colony-forming units/ml of urine are generally considered not clinically relevant. In conclusion, cystocenthesis is the preferred method of sampling for the evaluation of cats with suspected urinary tract infection.     

Escherichia coli isolates from commercial chicken meat and eggs cause sepsis,meningitis and urinary tract infection in rodent models of human infections

The zoonotic potential of Escherichia coli from chicken‐source food products is important to define for public health purposes. Previously, genotypic and phenotypic screening of E. coli isolates from commercial chicken meat and shell eggs identified some E. coli strains that by molecular criteria resembled human‐source extraintestinal pathogenic E. coli (ExPEC). Here, to clarify the zoonotic risk of such chicken‐source E. coli, we compared selected E. coli isolates from chicken meat and eggs, stratified by molecularly defined ExPEC status, to human‐source ExPEC and to laboratory E. coli for virulence in rodent models of sepsis, meningitis and UTI, and evaluated whether specific bacterial characteristics predict experimental virulence. Multiple chicken‐source E. coli resembled human‐source ExPEC in their ability to cause one or multiple different ExPEC‐associated infections. Swimming ability corresponded with urovirulence, K1 capsule corresponded with ability to cause neonatal meningitis, and biofilm formation in urine corresponded with ability to cause sepsis. In contrast, molecularly defined ExPEC status and individual genotypic traits were uncorrelated with ability to cause sepsis, and neither complement sensitivity nor growth in human urine corresponded with virulence in any infection model. These findings establish that chicken‐derived food products contain E. coli strains that, in rodent models of multiple human‐associated ExPEC infections, are able to cause disease comparably to human‐source E. coli clinical isolates, which suggests that they may pose a significant food safety threat. Further study is needed to define the level of risk they pose to human health, which if appreciable would justify efforts to monitor for and reduce or eliminate them.     

Efficacy and safety of cefovecin for the treatment of urinary tract infections in cats

OBJECTIVES: To determine the efficacy and safety of cefovecin (Convenia); Pfizer Animal Health) in the treatment of urinary tract infections in cats. METHOD: A multi-centre, masked, randomised study was conducted in cats presenting with clinical signs indicative of urinary tract infections. Cephalexin (Rilexine); Virbac) administered orally twice daily at 15 mg/kg bodyweight for 14 days was compared with a single subcutaneous injection of cefovecin in cats. The primary efficacy parameter assessed was bacterial elimination of the pretreatment uropathogen. RESULTS: Four hundred and thirty-four cats were screened for urinary tract infections. One hundred and eighty-five cats were treated with either cefovecin (n=124) or cephalexin (n=61). Ninety-seven cats (22.2 per cent) had confirmed bacteriuria and 82 cats were included in efficacy analysis. Escherichia coli was eliminated in 76.7 per cent (23 of 30) of cefovecin-treated cats compared with 62.5 per cent (10 of 16) of cephalexin-treated cats. Cefovecin demonstrated statistical non-inferiority compared with cephalexin for bacterial elimination. There were no suspected adverse drug reactions attributable to treatment with cefovecin or cephalexin. CLINICAL SIGNIFICANCE: Cefovecin was demonstrated to be an effective and safe treatment for urinary tract infections.     

Evaluation of modified Wright-staining of dried urinary sediment as a method for accurate detection of bacteriuria in cats

Background: Urinary sediment examination and quantitative urinary culture results are frequently discordant. Objectives: The aims of this study were to compare accuracy of light microscopic examination of wet‐mounted unstained (wet‐unstained) and air‐dried modified Wright‐stained (dry‐stained) sedimented preparations of urine with results of quantitative aerobic bacterial culture for detection and characterization of bacteriuria in cats. In addition, the presence of pyuria detected by urinalysis and potential risk factors were assessed. Methods: A blinded prospective study was conducted on 472 urinary samples collected from 410 cats by cystocentesis. The age and sex of each cat were recorded. Complete urinalyses were performed and included quantification of WBCs. Quantity and morphology of bacteria in each specimen were determined by light microscopic examination of wet‐unstained (performed by certified medical technologists) and dry‐stained (performed by a veterinary clinical pathologist) sedimented preparations of urine and compared with results of quantitative bacterial cultures. Results: Of 472 urinary specimens, 29 were positive for bacteriuria by culture and considered true positives and 443 were considered true negatives. Compared with these results, examination of wet‐unstained and dry‐stained urines had sensitivities of 75.9% and 82.8%, specificities of 56.7% and 98.7%, and test efficiencies of 57.8% and 97.7%, respectively. Positive likelihood ratios were 1.8 and 63.7 and negative likelihood ratios were 0.42 and 0.17 for wet‐unstained and dry‐stained examinations, respectively. Compared with 29 culture‐positive samples, the wet‐unstained method had morphologic concordance and misclassification rates of 37.9% and 62.1%, respectively, whereas the dry‐stained method had morphologic concordance and misclassification rates of 65.5% and 34.5%, respectively. Only 34% of samples with bacteriuria had pyuria. Frequency of bacteriuria was not significantly different based on age and sex of the cats, but there was a tendency for increased frequency in female cats and in cats >10 years old. Conclusions: Staining dried urinary sediment with a modified Wright‐stain significantly improved sensitivity, specificity, and test efficiency of microscopic detection and classification of bacteriuria compared with the wet‐unstained method. Pyuria should not be a criterion for determining the presence or absence of bacteriuria.     

Dried solidified blood calculi in the urinary tract of cats

We have noted an increased number of calculi submitted to the Gerald V. Ling Urinary Stone Analysis Laboratory, University of California, Davis, that do not contain crystalline material but appear to be composed of dried solidified blood (DSB). Canine and feline laboratory records from 1986-2003 were reviewed for samples composed of >99% DSB. No calculi from dogs were found, but specimens from 49 cats were composed of >99% DSB, of which almost half (n = 22) had been submitted after 2001. The DSB calculi had been removed surgically or by postmortem examination from all areas of the upper and lower urinary tract. All samples were well formed and could be divided in half with Rongeur forceps. Detailed case information was available for 12 cats. Urinalyses were available for 9 of the 12 cats, and the mean specific gravity was 1.017 (range, 1.009-1.032). Red blood cells were reported in the sediment of all cats, with most containing >100 RBC/hpf. Ureteral obstructions but no radio-opaque calculi were visible by radiography, including radiographic contrast studies. Reports of ultrasound examinations were available for 10 cats, and discrete calculi were not recorded. In addition to polarized light microscopy, infrared spectroscopy and electron probe microanalysis were performed on a subset (n = 6, DSB calculi; n = 3, control calculi) of samples. Significantly more carbon, nitrogen, and sulfur (P = .012, P = .02, and P = .012, respectively) were present in the elemental analysis of the DSB calculi than in the control calculi, suggesting that the DSB calculi are primarily formed from organic material. At this time, we are uncertain why these DSB calculi become solidified, and we recommend that samples be submitted both in formalin and preservative free to further investigate their etiology.     

Evaluation of catheter-associated urinary tract infections and multi-drug-resistant Escherichia coli isolates from the urine of dogs with indwelling urinary catheters

OBJECTIVE: To determine the frequency of urinary tract infections (UTIs) in dogs with indwelling urinary catheters in an intensive care unit (ICU) and the frequency of multi-drug-resistant (MDR) Escherichia coli UTIs in those dogs. DESIGN: Prospective study. ANIMALS: All dogs in the ICU with an indwelling urinary catheter from January 2003 through December 2003. PROCEDURES: Urine samples and rectal swab specimens were collected at admission and every 3 days until discharge from the hospital. Escherichia coli isolates from urine samples and rectal swab specimens and those from dogs that were temporally or spatially associated with dogs with MDR E coli UTIs underwent antimicrobial susceptibility testing. Pulsed-field gel electrophoresis was performed on MDR isolates from urine and rectal swab specimens. RESULTS: Urinary catheters were placed in 137 dogs. Twenty-six UTIs were diagnosed, 15 on the day of admission and 11 after 3 or more days of catheterization. Of 12 dogs with E coli UTIs, 6 were infected at admission and 6 acquired the infection in the ICU. Two MDR E coli UTIs were detected, 1 of which was acquired in the ICU. One MDR E coli urinary isolate had an electrophoresis pattern similar to that of rectal isolates from the same dog. Urinary E coli isolates were most frequently resistant to ampicillin and cephalothin. CONCLUSIONS AND CLINICAL RELEVANCE: The ICU-acquired MDR E coli UTI likely originated from the dog's intestinal flora during hospitalization. Dogs that have been referred from a community practice may have MDR E coli UTIs at the time of admission.