Corynebacterium Renale

Also known as

Contagious bovine pyelonephritis (urinary tract infection involving kidneys)

Description

Corynebacterium renale causes infection of the urinary tract of cattle, characterized by chronic purulent (pus-forming) inflammation in the bladder, ureters and kidneys.

Corynebacterium renale, C. cystitidis, and C. pilosum are all related bacteria, sometimes referred to as the C. renale group. C. renale causes pyelonephritis in cattle. C. pilosum and C. cystitis cause posthitis (inflammation of the foreskin of the penis), also known as pizzle rot or sheath rot, in sheep and goats.

These bacteria are always present in the environment and inhabit the vagina and prepuce of cattle. High-protein diets, resulting in higher urea excretion and more basic urine (low acid content), can cause irritation of the vaginal and prepuce mucous membranes.

These are contributing factors that allow the infection to start. The excess ammonia produced (and excreted in urine) can irritate the preputial and vulvar skin, increasing vulnerability to infection. This condition can occur in any animals consuming high protein feeds, including young bulls on high protein rations or lush pasture.

Corynebacterium renale is a normal inhabitant of bovine genitourinary tracts. Trauma, urinary tract obstruction, and abnormalities in structure of the tract may predispose an animal to infection. Basic pH urine levels may hinder some immune defenses. Infections ascend through the urinary tract, eventually reaching the kidneys.

Ascending infection is most common in adult cows within a few weeks after calving, and can occasionally occur in calves as a complication of umbilical artery infection. Other predisposing factors are vaginal/uterine infection or immunosuppression.

Periodic episodes of blood or pus in the urine, cloudy urine, colic (abdominal pain), straining to urinate, fever, loss of weight, and drop in milk production are common signs.

Abnormality of kidneys, ureters, and bladder (thickening and contraction of the bladder wall and enlargement of both ureters, enlargement of one or both kidneys) can be detected on rectal palpation.

Cystitis (bladder infection) is determined by endoscopic examination, and urinary tract infection by ultrasound examination. The presence of Corynebacterium renale in a urine sample can be determined by culture or microscopic examination.

Signs 

• Blood, pus or mucus in the urine (especially in the final part of the flow)
• Frequent painful urination
• Acute colic
• Fluctuating fever and appetite
• Weight loss
• Drop in milk production

Cause

Corynebacterium renale is a pathogenic bacterium that causes cystitis (bladder infection) and urinary tract infection in cattle. There are several different strains. This anaerobic (thriving in environments with no oxygen) gram-positive organism is rod-shaped and forms aggregations when cultured, that look like Chinese writing.

At least three serotypes exist as normal flora in the rear portion of the reproductive tract of female cattle and the sheath of male cattle. Unlike most gram-positive organisms, C. renale possesses pili (short, hair-like structures on the cell surface) that enable these bacteria to attach to and colonize the urinary tract mucosal lining.

In addition, the pili contain an antigenic protein which causes inflammation of the bladder tissue. These bacteria produce a urease (an enzyme that hydrolyzes urea into ammonium carbonate) that hydrolyzes urea, releasing ammonia that causes localized epithelial damage and increased urine pH.

Conditions that create physical or chemical damage to the mucosa in the lower portion of the urinary tract include dystocia (difficult calving), bladder paralysis, or catheterization. The damage to the mucosa may predispose the cow to C. renale infection ascending from the urinary bladder to the ureters and kidneys. Urinary tract infection is common if any part of the tract is blocked,

This disease is sporadic, even in herds that have a significant number of carriers with sub-clinical infections. It can be fatal, however, unless treated early in the course of the disease.

Young animals are rarely affected. Cows seem more susceptible than bulls. Increase in numbers of cases often occur in colder seasons and in heavily fed, high-producing dairy herds.

These bacteria often adhere to the epithelial cells of the bovine vulva. Infected cows or normal-appearing carrier cows are probably the main source of infection for other cattle, since the disease can be transmitted via direct contact, such as during breeding (spread by infected bulls or cows). The pathogen can be found on the prepuce and urethra of bulls.

C. renale is the most frequently isolated bacterium in cases of pyelonephritis (ascending urinary tract infection that has reached the kidneys) because of its ability to grow in urine. It predominantly affects females, such as cows, ewes and mares, producing inflammation of the bladder, ureters, kidney, and pelvis. This pathogen is highly adapted to the bovine urinary tract through its complex structure and metabolism.

Transmission between animals occurs when contaminated droplets of urine are splashed on the vulvar area of a susceptible animal from an infected carrier, but in diseased herds C. renale can also be found in healthy animals without affecting them.

Cows with pyelonephritis and urethritis (inflammation of the urethra) have a serum antibody response to these bacteria but not enough to fully combat the infection. Untreated animals seldom recover.

A urinary tract infection can progress from the bladder to the ureters and kidneys. Damage to the kidneys and obstruction of urine can ultimately result in uremia (presence in the bloodstream of urea and other nitrogenous waste compounds that are normally eliminated by the kidneys) and death of the animal.

Prevention

Prevention includes avoidance of urinary catheterization. Isolation of affected animals and destruction of infected bedding can minimize transmission to other animals in the herd. If the disease is being spread by breeding, use of artificial insemination (with proper sanitary techniques) may reduce the incidence of cases.

Treatment

C. renale is sensitive to penicillin, ampicillin, streptomycin, kanamycin, erythromycin, polymycin B, cephalosporins, quinolones, tetracyclines, cefuroxime, and trimethoprim.

Penicillin in large doses is usually the antibiotic of choice--administered daily for 10 days. If treatment is begun early, before permanent damage is done, the animal generally recovers. If treatment is begun late, or in chronic cases, relapses are common.

The preputial orifice (opening in the sheath of the penis) of affected bulls should be debrided (damaged tissue removed) followed by topical application of any of the intra-mammary preparations of penicillin or cloxacillin (which are used for treating mastitis), with more severe cases also being treated with systemic administration of penicillin.