Encrusted cystitis secondary to Corynebacterium matruchotii infection in a horse.

This research study examines a case of a 17-year-old horse suffering from severe urinary symptoms, which was later identified as encrusted cystitis caused by infection from a specific bacterium, Corynebacterium matruchotii – a novel discovery within equine veterinary science.

Background and Initial Findings

• The horse in question was brought for evaluation due to signs of painful urination (dysuria), loss of appetite, and weight loss. It’s important to note that these symptoms are general and could be indicative of a range of disorders.
• Upon performing cystoscopy, a procedure that inspects the urinary bladder, the team found significant bruising and bleeding within the bladder, along with crystal-like sludge formations.

Lab Analysis and Diagnosis

• A urine sample showed several abnormalities – it was the same concentration as normal plasma (isosthenuria), had an alkaline pH, featured pus and blood cells, bacteria, and a lot of calcium carbonate crystals. The latter, especially, is indicative of urinary system disruptions.
• Biopsy of bladder tissue found severe infiltration by neutrophils, a type of white blood cell typically indicative of infection, and mineralization, suggesting urinary stone formation.
• Together, these findings led to the diagnosis of encrusted cystitis, a severe form of bladder inflammation with associated mineral encrustations, compounded by “sabulous urolithiasis“, or sandy urinary stones.

Identification of the Culprit Bacterium

• A microbe was cultured from the urine and bladder biopsy, belonging to the Corynebacterium genus. This bacterium was found susceptible to penicillin, sulfonamide, and enrofloxacin – all antibacterial drugs.
• To find out the exact species, the team extracted the 16S rDNA gene sequence from the bacterium, and performed molecular phylogenetic analysis, a method to draw an evolutionary relationship on the basis of gene data.
• The result was Corynebacterium matruchotii, a bacterium previously not known to cause encrusted cystitis in horses.

Treatment

• The horse was given Penicillin G potassium intravenously for 5 days, followed by a 4-weeks course of trimethoprim-sulfamethoxazole, two antibiotics
• The bladder was rinsed daily for three days with electrolyte solution and dimethyl sulfoxide, helping in the expulsion of accumulated dead tissues and bladder sludge.