Subclinical Bacteriuria in Older Cats and its Association with Survival

Value of repeated health screening in 259 apparently healthy mature adult and senior cats followed for 2 years

BACKGROUND

Although regular health screening is recommended, long-term follow-up data in healthy aged cats are lacking.

OBJECTIVES

Determine the most common conditions in a large group of apparently healthy older cats and which diseases are manifested within 2 years in cats confirmed to be healthy based on extensive health screening.

ANIMALS

Client-owned cats.

METHODS

Prospective study. Thorough history, physical examination, blood tests, and urinalysis were performed in 259 apparently healthy mature adult (7-10 years) and senior (>10 years) cats. Semi-annual follow-up examinations were performed in 201 confirmed healthy cats.

RESULTS

At baseline, 21% of apparently healthy cats were not considered healthy but were diagnosed with International Renal Interest Society (IRIS) ≥ stage 2 chronic kidney disease (CKD; 7.7%) or hyperthyroidism (4.6%), among other disorders. Disease occurred significantly more frequently in senior cats compared with mature adult cats. In addition, 40% cats were overweight, 35% had moderate to severe dental disease, and 22% had abnormal cardiac auscultation findings. Within 2 years, 28% of mature adult and 54% of senior cats that were confirmed healthy at inclusion developed new diseases, most commonly IRIS ≥ stage 2 CKD (cumulative incidence, 13.4%), hyperthyroidism (8.5%), chronic enteropathy, hepatopathy or pancreatitis (7.5%), or neoplasia (7%).

CONCLUSIONS AND CLINICAL IMPORTANCE

The high prevalence and 2-year incidence of physical examination abnormalities and systemic diseases in apparently healthy older cats argue for regular health screening in cats ≥7 years of age. Although more common in senior cats, occult disease also occurs in mature adult cats, and owners should be informed accordingly.

Analysis of lower urinary tract signs and bacteriuria in cats with subcutaneous ureteral bypass systems

Objectives

Distinguishing bacterial cystitis from subclinical bacteriuria is necessary for feline treatment protocols and antimicrobial stewardship. This can be challenging in cats with subcutaneous ureteral bypass (SUB) systems because they may present with lower urinary tract signs without bacteriuria. We investigated the relationship between positive urine culture and lower urinary tract signs in cats with SUBs, including factors associated with each.

Methods

Clinical records were retrospectively reviewed to identify cats presenting with ureteral obstruction that underwent placement of a SUB device(s). The relationship between a positive urine culture and lower urinary tract signs was determined by chi-squared analysis. Univariable and multivariable logistic regression models were performed to identify factors associated with positive urine cultures and lower urinary tract signs.

Results

Two hundred and thirty visits were recorded for 61 cats, with 36 of 230 (16%) positive cultures in 21 of 61 (34%) cats. Lower urinary tract signs were documented at 97 of 230 (42%) visits, with 37 of 61 (61%) cats demonstrating lower urinary tract signs at some point. No relationship was found between culture results and lower urinary tract signs. Risk factors for a positive culture were higher urine pH, higher urine white blood cells and the presence of bacteriuria on microscopy. Risk factors for lower urinary tract signs were younger age and being a purebred cat (vs. non-purebred).

Conclusions

A high proportion of cats with SUBs exhibited sterile lower urinary tract signs, making differentiation between bacterial cystitis and subclinical bacteriuria difficult. This highlights the need for clearer guidelines on when to treat bacteriuria in cats with SUBs.

Bacteriuria in Cystocentesis Samples from Cats in the United Kingdom: Prevalence, Bacterial Isolates, and Antimicrobial Susceptibilities

Bacterial urinary tract infections (UTIs) have historically been reported to be uncommon in cats; however, recent studies showed a higher prevalence. Bacterial UTIs are one of the most common reasons for the use of antimicrobial drugs in veterinary medicine. Our aim was to investigate the prevalence of positive cultures in urine samples submitted to a UK laboratory for testing, as well as prevalence of bacterial species and their antimicrobial susceptibility to commonly used antibiotics. This was a retrospective analysis of positive cultures from feline urine samples collected by cystocentesis submitted over 14 months (January 2018-February 2019). A total of 2712 samples were reviewed, of which 425 documented a positive culture (15.7%) with a total of 444 bacterial isolates. E. coli (43.7%), other Enterobacterales (26.4%), Enterococcus species (14.9%) and Staphylococcus species (9.2%) were the most commonly isolated bacteria. E. coli most commonly showed resistance to cephalexin (20.7%) and amoxicillin (16.7%). Resistance was most commonly seen against amoxicillin (64.1%) and cephalexin (52.2%) in Enterobacterales. Enterococcus species most commonly showed resistance to trimethoprim/sulfamethoxazole (94.3%). Staphylococcus species most commonly showed resistance to amoxicillin (20%). This study showed significant resistance of bacteria found in feline urine samples in the UK to frequently used antibiotics.

Clinical differences in enterococcal bacteriuria compared with other bacteriuria in cats

OBJECTIVES

The clinical differences between Enterococcus species bacteriuria compared with other bacteria has been reported in a small number of cats. The objective of this study was to compare a large number of cats with Enterococcus species bacteriuria to cats with other bacteriuria and determine the clinical differences. It was hypothesized that enterococcal bacteriuria would be associated with subclinical bacteriuria and polymicrobial infections more than other bacteriuria, and that when local or systemic comorbidities were present, enterococcal bacteriuria would be more common.

METHODS

This retrospective case-control study compared case cats with enterococcal bacteriuria to control cats with other bacteriuria. Cats with enterococcal bacteriuria were age, year and weight matched with 1-2 control cats with any other bacteriuria.

RESULTS

Lower urinary tract clinical signs were statistically significantly more common in controls (n = 38/77 [49%]) compared with Enterococcus cases (n = 12/47 [25%]; P = 0.01). Specifically, control cats (n = 20/77 [26%]) were statistically significantly more likely to have gross hematuria compared with Enterococcus case cats (n = 3/47 [6%]; P = 0.01). Enterococcus cases were statistically significantly more likely to have a polymicrobial infection compared with controls (odds ratio 5.84, 95% confidence interval 1.33-34.70; P = 0.01).

CONCLUSIONS AND RELEVANCE

Enterococcus species are associated with subclinical bacteriuria and polymicrobial urinary tract infections in cats vs other bacteriuria.

Prevalence of bacteriuria in cats with neurogenic bladder

Urinary tract infections are defined as the adherence, multiplication, and persistence of an infectious agent within the urogenital system, causing an associated inflammatory response and clinical signs; instead, the presence of bacteria in urine as determined by positive bacterial culture (PUC) from a properly collected urine specimen, in the absence of clinical signs, is defined subclinical bacteriuria. Limited information on the prevalence of PUC in spinal cord injury cats affected by neurogenic bladder (NB) is available. On contrary, in NB dogs and humans the prevalence of bacteriuria is well documented. Moreover, while in humans information about bacteriemia associated with NB is already available, this aspect has never been studied in NB cats. The aim of this prospective study was to determine the prevalence of PUC in cats with NB, compared to animals affected by chronic kidney disease (CKD) and healthy cats. Furthermore, the prevalence of bacteriemia in cats with NB was evaluated. Fifty-one cats met the inclusion criteria: 12 cats were affected by NB, 22 had CKD and 17 were healthy. The prevalence of PUC was 58.33% and 18% in NB and CKD cat populations, respectively. All blood cultures were negative. The incomplete bladder emptying and the decreased resistance in the bladder wall could be considered predisposing elements to PUC in the NB feline population. The results of this study highlight, for the first time, an high prevalence of PUC in cats affected by NB, which was not found to be associated with bacteriemia.

Prevalence of, and factors associated with, positive urine cultures in hyperthyroid cats presenting for radioiodine therapy

OBJECTIVES

Urinary tract infections (UTIs) are reported to be relatively common in hyperthyroid cats, with prevalence rates ranging from 12% to 22%. Factors that are associated with UTIs include age, decreasing body weight and active urine sediments. The purpose of this study was to investigate the prevalence of positive urine cultures (PUCs) in hyperthyroid cats and associated risk factors for PUC.

METHODS

In total, 197 hyperthyroid cats presenting for radioiodine therapy had urine cultures prospectively performed on cystocentesis samples. Data pertaining to clinical signs, drug history, age, weight, blood urea nitrogen, creatinine, serum thyroxine and urinalysis were also evaluated.

RESULTS

The prevalence of PUCs in this population of hyperthyroid cats was 5.1% and all cats were subclinical. Microscopic bacteriuria was significantly associated with a PUC (60%) compared with a negative urine culture (1.6%) status. Age, weight, urine specific gravity <1.020, urine pH, hematuria, pyuria, thyroxine concentration, breed and sex were not associated with PUC status.

CONCLUSIONS AND RELEVANCE

The prevalence of PUCs in this population of cats was lower than previous reports of cats with hyperthyroidism. Cats with a PUC were subclinical at the time of culture, regardless of urine sediment abnormalities. Further studies are necessary to determine the clinical significance of subclinical bacteriuria in hyperthyroid cats.

[Bacterial urinary tract infection and subclinical bacteriuria in the dog: a current review]

Bacterial urinary tract infection (UTI) is a common clinical presentation in dogs and a frequent reason for the prescription of antimicrobial drugs. UTI refers to adherence, multiplication and persistence of an infectious agent within the urogenital system. This causes an associated inflammatory response as well as the pertaining clinical signs. Depending on the site of infection, UTI's may be classified as bacterial cystitis, prostatitis or pyelonephritis. In contrast, subclinical bacteriuria (SB) is defined as the presence of a significant number of bacteria in the urine of an individual not showing clinical signs referrable to UTI. UTI's typically occur as a consequence of ascending pathogen migration from the host's own fecal or distal urogenital microbial flora. The most commonly isolated pathogen in cases of UTI and SB is Escherichia coli. The diagnosis is based on clinical signs and the results of urine examination and culture. The recently revised guidelines of the International Society for Companion Animal Infectious Diseases provide detailed recommendations for diagnosis and management of different forms of bacterial UTI's in dogs. Adherence to treatment guidelines will improve treatment success and is imperative in avoiding further deterioration of the antimicrobial resistance situation.

Subclinical bacteriuria in a mixed population of 179 middle-aged and elderly cats: a prospective cross-sectional study

OBJECTIVES

Subclinical bacteriuria (SBU) is the presence of bacteria in urine with no clinical evidence of lower urinary tract disease. The aims of this study were to investigate if being overweight and/or obesity predispose cats to SBU, to investigate previously reported risk factors and to determine the prevalence of SBU in a prospectively sampled cohort of middle-aged and elderly cats.

METHODS

Cats aged ⩾6 years presenting to the University Hospital for Companion Animals in Copenhagen from 2015-2019 for causes unrelated to the lower urinary tract were eligible for enrolment. Body condition scoring was performed on a 9-point scale. Overweight was defined as a body condition score (BCS) ⩾6 and obese as a BCS ⩾8. The correlation between SBU and the variables of sex, healthy/diseased, age, BCS and comorbidities (chronic kidney disease, diabetes mellitus, hyperthyroidism, hepatic disorders and gastrointestinal disease) were analysed by binominal logistic regression.

RESULTS

In total, 179 cats ranging from 6-20 (median 10) years of age were included. SBU was identified in 11/179 cats (6.1%). Being overweight was not a significant risk factor (overweight/obese odds ratio [OR] 0.3, 95% confidence interval [CI] 0.06-1.6, relative risk [RR] 0.3 [95% CI 0.05-1.3] vs lean; P = 0.2) and neither was obesity compared with lean and overweight cats (P = 0.99). Female sex (OR 6.2 [95% CI 1.3-30], RR 4.7 [95% CI 1.5-12] vs male; P = 0.02) and the presence of hepatic disease (OR 7.5 [95% CI 1.4-39], RR 5.3 [95% CI 1.3-12]; P = 0.02) were significant risk factors.

CONCLUSIONS AND RELEVANCE

The prevalence of SBU in cats is low, and being overweight/obese was not identified as a predisposing factor. The increased risk associated with hepatic disease has not been previously reported, and further studies are needed to confirm this finding.

Hyperthyroidism is not a risk factor for subclinical bacteriuria in cats: A prospective cohort study

Background

Subclinical bacteriuria is defined as a positive bacterial urine culture in the absence of clinical evidence of urinary tract infection (UTI). Studies have reported that hyperthyroid cats have UTIs (mostly subclinical) with prevalence rates of 12%‐22%. Consequently, clinicians consider hyperthyroidism a risk factor for development of subclinical bacteriuria, and many recommend urine culture when evaluating hyperthyroid cats.

Objectives

To compare the prevalence of subclinical bacteriuria (based on positive urine culture) in untreated hyperthyroid cats to that in euthyroid cats of similar age and sex.

Animals

Three hundred and ninety‐three hyperthyroid cats presented for radioiodine treatment and 131 euthyroid cats (≥7 years of age) presented for routine examination. Cats with signs of lower urinary tract disease were excluded.

Methods

Prospective cohort study. Both hyperthyroid and euthyroid cats had urine collected by cystocentesis for complete urinalysis and culture. Data pertaining to age, sex, body condition, and serum thyroxine and creatinine concentrations also were acquired. Logistic regression was performed to evaluate for potential risk factors for subclinical bacteriuria.

Results

Hyperthyroid cats showed a low prevalence of subclinical bacteriuria (4.3%), which did not differ from that found in euthyroid cats (4.6%). Of the signalment factors evaluated, only female sex was a significant risk factor (odds ratio [OR], 6.9; P = .002). Furthermore, positive urine cultures were more likely in specimens with dilute urine concentration (<1.035), pyuria, or microscopic bacteriuria.

Conclusions and Clinical Importance

Hyperthyroid cats are not at risk for subclinical bacteriuria. In the absence of lower urinary tract signs, no clinical benefit exists in routinely performing urine cultures when evaluating hyperthyroid cats.

Influence of preanalytic and analytic variables in canine and feline urine specific gravity measurement by refractometer

Urine specific gravity (USG), which is usually measured by refractometry, is an important indicator of renal concentrating ability. Few studies have evaluated refractometers with separate scales for canine and feline urine. Variables such as protein content or storage time may influence the USG. We compared the effects of measuring USG with a refractometer with single or separate scales for canine and feline urine, investigated inter- and intra-observer variability, and measured agreement between whole urine and supernatant. We evaluated the correlation between USG and osmolality, the influence of urinary protein on USG and osmolality, and the impact of storage time up to 6 mo. We examined 252 canine and 126 feline samples. Bland-Altman analysis revealed higher USG values of the single-scale refractometer than the dual-scale refractometer, with a mean difference (bias) of < 0.001 for canine and 0.003 for feline specimens. Inter- and intra-observer variability were acceptable. Good agreement was shown between USG of whole urine and supernatant. Correlations between USG and osmolality were excellent (0.98-0.99, p < 0.001). Proteinuria up to 1 g/L had no major impact on USG or osmolality. Storage time had no significant effect on USG. The difference between the refractometers is clinically irrelevant, and the use of a refractometer with separate feline and canine scales is unnecessary. Whole urine and supernatant stored up to 6 mo can both be used for USG measurement. The influence of proteinuria <1 g/L on USG and osmolality is negligible.

A clinical approach to multidrug-resistant urinary tract infection and subclinical bacteriuria in dogs and cats

Multidrug-resistant bacteria are increasingly isolated from the urinary tract of pets, particularly those that suffer from concurrent conditions, have been hospitalised, or were treated with antimicrobials in the recent past. Many of the multidrug-resistant bacteria encountered are resistant to all commonly used oral antibiotics. This poses both a therapeutic dilemma in the individual pet and a threat to public health. This article begins with an overview of multidrug resistance in organisms that are commonly isolated from the urinary tract of pets. This is followed by a proposed clinical approach to managing multidrug-resistant urinary bacteria, which summarises current knowledge regarding appropriate sampling and analysis, reviews the current guidelines regarding appropriate antimicrobial use and discusses treatment options that might be considered. The article highlights several shortcomings of the current knowledge to be considered when planning future clinical research and developing policies.

Urinary tract infection and subclinical bacteriuria in cats: A clinical update

PRACTICAL RELEVANCE

Urinary tract infection (UTI) is an important cause of feline lower urinary tract disease (FLUTD), particularly in female cats older than 10 years of age. In addition to cats with typical clinical signs of FLUTD or upper UTI, many cats have subclinical bacteriuria, but the clinical relevance of this is currently uncertain. UTIs are one of the most important indications for antimicrobial use in veterinary medicine and contribute to the development of antimicrobial resistance. Adherence to treatment guidelines and confinement to a few first-line antimicrobial agents is imperative to avoid further deterioration of the antimicrobial resistance situation. The decision to treat with antimicrobials should be based on the presence of clinical signs, and/or concurrent diseases, and the results of urine culture and susceptibility testing.

CLINICAL CHALLENGES

Distinguishing between cats with bacterial cystitis, and those with idiopathic cystitis and concurrent clinical or subclinical bacteriuria, is challenging, as clinical signs and urinalysis results may be identical. Optimal treatment of subclinical bacteriuria requires clarification as there is currently no evidence that demonstrates a beneficial effect of routine treatment. Management of recurrent UTIs remains a challenge as evidence for most alternatives used for prevention in cats is mainly anecdotal, and no preventive treatment modality is currently recommended.

EVIDENCE BASE

This review draws on an extensive literature base in veterinary and human medicine, including the recently updated guidelines of the International Society for Companion Animal Infectious Diseases for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Where published evidence is lacking, the authors describe their own approach; notably, for the bacteriuric cat with chronic kidney disease.

International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats

Urinary tract disease is a common clinical presentation in dogs and cats, and a common reason for antimicrobial prescription. This document is a revision and expansion on the 2011 Antimicrobial Use Guidelines for Treatment of Urinary Tract Disease in Dogs and Cats, providing recommendations for diagnosis and management of sporadic bacterial cystitis, recurrent bacterial cystitis, pyelonephritis, bacterial prostatitis, and subclinical bacteriuria. Issues pertaining to urinary catheters, medical dissolution of uroliths and prophylaxis for urological procedures are also addressed.

Prevalence of feline urinary tract pathogens and antimicrobial resistance over five years

The aim of this retrospective study was to document the prevalence of bacterial species in cats with significant bacteriuria and to compare their antimicrobial susceptibilities over five years. One hundred sixty-nine positive urine cultures from 150 cats were included. Fifty-five per cent showed clinical signs, while 40 per cent had subclinical bacteriuria. Escherichia coli, Staphylococcus species, Enterococcus species, Streptococcus species and Proteus mirabilis accounted for 50.5 per cent, 22.9 per cent, 15,1 per cent, 3.6 per cent and 2.6 per cent, respectively. Enterococcus species was significantly more common in cats with subclinical bacteriuria. Enterococcus species and Proteus mirabilis isolates were resistant to a significantly higher number of antimicrobials than other isolates. Applying the formula to select rational antimicrobial therapy, bacterial isolates were most likely to be susceptible to imipenem, nitrofurantoin, gentamicin and amoxicillin clavulanic acid. Over the study period, only minor differences were noted for the antimicrobial impact factors (IFs) between years and between cats with and without clinical signs. The cumulative IF increased significantly compared with the previous 10 years. Empirical treatment of bacterial cystitis should be avoided whenever possible and, if needed, based on the locally determined bacterial spectrum and antibiotic susceptibility.