Clinical description of Corynebacterium urealyticum urinary tract infections in 11 dogs and 10 cats

2025 iCatCare consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats

PRACTICAL RELEVANCE

Lower urinary tract signs (LUTS) such as dysuria, haematuria, periuria, pollakiuria and stranguria can occur as the result of a variety of underlying conditions and diagnostic investigation is required to uncover the underlying cause and select appropriate treatment.

AIM

The '2025 iCatCare consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats' provide an overview of the common presenting signs caused by underlying feline lower urinary tract (LUT) diseases in cats, which often are indistinguishable between different underlying causes. The Guidelines set out a diagnostic approach to affected cats before focusing on the most common causes of LUTS: feline idiopathic cystitis (FIC), urolithiasis, urinary tract infection and urethral obstruction. The aim is to provide practitioners with practical information on these problematic conditions.

CLINICAL CHALLENGES

The fact that LUTS are similar despite different underlying causes creates a diagnostic challenge. The most common cause of LUTS, FIC, is challenging to manage due to a complex pathogenesis involving organs outside the LUT. Urethral obstruction is a life-threatening complication of various underlying LUT diseases and recurrent LUTS can lead to relinquishment or euthanasia of affected cats.

EVIDENCE BASE

These Guidelines have been created by a panel of experts brought together by International Cat Care (iCatCare) Veterinary Society (formerly the International Society of Feline Medicine [ISFM]). Information is based on the available literature, expert opinion and the panel members' experience.

Corynebacterium oculi-related bacterium may act as a pathogen and carrier of antimicrobial resistance genes in dogs: a case report

BACKGROUND

The genus Corynebacterium comprises well-known animal and human pathogens as well as commensals of skin and mucous membranes. Species formerly regarded as contaminants are increasingly being recognized as opportunistic pathogens. Corynebacterium oculi has recently been described as a human ocular pathogen but has so far not been reported in dogs.

CASE PRESENTATION

Here we present two cases of infection with a novel Corynebacterium sp., a corneal ulcer and a case of bacteriuria. The two bacterial isolates could not be identified by MALDI-TOF MS. While 16 S rRNA gene (99.3% similarity) and rpoB (96.6% identity) sequencing led to the preliminary identification of the isolates as Corynebacterium (C.) oculi, whole genome sequencing revealed the strains to be closely related to, but in a separate cluster from C. oculi. Antimicrobial susceptibility testing showed high minimal inhibitory concentrations of lincosamides, macrolides, tetracycline, and fluoroquinolones for one of the isolates, which also contained an erm(X) and tet-carrying plasmid as well as a nonsynonymous mutation leading to an S84I substitution in the quinolone resistance determining region of GyrA.

CONCLUSIONS

While the clinical signs of both dogs were alleviated by antimicrobial treatment, the clinical significance of these isolates remains to be proven. However, considering its close relation with C. oculi, a known pathogen in humans, pathogenic potential of this species is not unlikely. Furthermore, these bacteria may act as reservoir for antimicrobial resistance genes also in a One Health context since one strain carried a multidrug resistance plasmid related to pNG3 of C. diphtheriae.

Pseudomembranous cystitis in cats with presumed or confirmed mineralization: A retrospective study of 26 cases (2016-2021)

BACKGROUND

Pseudomembranous cystitis (PMC) in cats is a recognized disease, but concurrent mineralization is reported rarely and its outcome is poorly described.

HYPOTHESIS AND OBJECTIVES

Describe a population of cats with PMC and the prevalence of concurrent mineralization.

ANIMALS

Twenty-six cats with PMC.

METHODS

Medical records were retrospectively reviewed (January 2016 to December 2021). Cats with an ultrasound diagnosis of PMC were included. Clinicopathologic results, imaging, treatment, and outcome were reviewed.

RESULTS

All cats were male and 21 (80%) were diagnosed with urethral obstruction (UO). Five cats (23.8%) had positive urine culture (Staphylococcus felis, 3/5; Proteus mirabilis, 2/5) with a median urine pH of 8 (range, 6-9). All cats had ultrasonographic changes suggestive of mineralization. On ultrasound examination, 10 cats (38.5%) had pseudomembranes with acoustic shadowing suggestive of mineralization, 15 (57.7%) had changes indicative of ulceration, and 8 (31%) had changes compatible with of a urachal anomaly. Twenty-two cats received medical treatment, 4 underwent surgery (3 percutaneous cystolithotomy, 1 cystotomy). Twenty cats (77%) survived to discharge. Follow-up ultrasound examination indicated resolution of PMC in 6/7 cats, 4 had persistent hyperechoic bladder lining. Five of 12 cats with follow-up had a relapse of lower urinary tract signs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Pseudomembranous cystitis was diagnosed mainly in male cats with UO and imaging findings suggestive of mineralization were present in all cases. Frequent negative urine culture suggests a different etiology than encrusting cystitis related to urease-positive bacteria. Good outcomes can be achieved with medical management.

Vasovagal reaction secondary to bladder overdistension in a dog undergoing a unique timeline of medical and surgical treatment for Corynebacterium urealyticum encrusting cystitis: a case report

BACKGROUND

Corynebacterium urealyticum urinary tract infections can result in a rarely reported condition called encrusting cystitis whereby plaque lesions form on and within the urinary bladder mucosa. Chronic lower urinary tract signs manifest subsequent to the infection-induced cystitis and plaque-induced decreased bladder wall distensibility. Because of the organism's multidrug resistance and plaque forming capability, infection eradication can be difficult. While systemic antimicrobial therapy is the mainstay of treatment, adjunctive surgical debridement of plaques has been used with relative paucity in such cases, thereby limiting our understanding of this modality's indications and success rate. Consequently, this report describes the successful eradication of Corynebacterium urealyticum encrusting cystitis utilizing a unique timeline of medical and surgical treatments. Additionally, this represents the first reported veterinary case of a vasovagal reaction due to bladder overdistension.

CASE PRESENTATION

A 6-year-old female spayed Miniature Schnauzer was evaluated for lower urinary tract clinical signs and diagnosed with Corynebacterium urealyticum encrusting cystitis. The infection was persistent despite prolonged courses of numerous oral antimicrobials and urinary acidification. A unique treatment timeline of intravenous vancomycin, intravesical gentamicin, and mid-course surgical debridement ultimately resulted in infection resolution. During surgery, while the urinary bladder was copiously flushed and distended with saline, the dog experienced an acute vasovagal reaction from which it fully recovered.

CONCLUSIONS

Surgical debridement of bladder wall plaques should be considered a viable adjunctive therapy for Corynebacterium urealyticum encrusting cystitis cases failing to respond to systemic antibiotic therapy. The timing in which surgery was employed in this case, relative to concurrent treatment modalities, may be applicable in future cases of this disease as dictated on a case-by-case basis. If surgery is ultimately pursued, overdistension of the urinary bladder should be avoided, or at least minimized as much as possible, so as to prevent the possibility of a vasovagal reaction.

Assessment of bacterial and fungal populations in urine from clinically healthy dogs using next-generation sequencing

BACKGROUND

Urine from clinically healthy dogs is not sterile. Characterizing microbial diversity and abundance within this population of dogs is important to define normal reference ranges for healthy urine.

OBJECTIVES

To establish composition and relative representation of bacterial and fungal microbiomes in urine of clinically healthy dogs.

ANIMALS

Fifty clinically healthy dogs.

METHODS

Analytic study. Urine sampling via cystocentesis. Comprehensive evaluation of urine including standard urinalysis, culture and sensitivity, next-generation sequencing (NGS), and bioinformatics to define bacterial and fungal microbiome.

RESULTS

Culture did not yield positive results in any samples. Next-generation sequencing of urine established low presence of bacteria, fungi, or both in all samples. Diversity and abundance of bacterial and fungal communities varied between urine samples from different dogs. Struvite crystals were associated with bacterial community structure (P = .07) and there was a positive correlation between struvite crystals and pH.

CONCLUSIONS AND CLINICAL IMPORTANCE

The microbiome in urine of clinically healthy dogs has diverse bacterial and fungal species These findings highlight limitations of conventional culture testing and the need for culture-independent molecular diagnostics to detect microorganisms in urine.

[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.

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.