General information
The sensitivity of the assay is 10 organisms per 1 gram of feces. The PCR will amplify DNA that is directly extracted from fecal material.
We need approximately 0.5 gram of fecal material. The sample should be taken from the abnormal loose stool and must be free of cat litter.
For storage and shipping, add approximately an equal amount of rubbing alcohol (isopropyl alcohol) to the tube. This way, no refrigeration or freezing is necessary during the shipment. If no alcohol is available, place the sample in the freezer, and ship with a frozen gel ice pack.
Our stability studies have shown that DNA in fecal samples is stable for up to 72 hours under refrigeration and for at least four weeks when frozen at -20°C.
Turnaround: 1-3 business days after receipt of samples. This time may vary depending upon day and time the samples are received. See assay schedule.
General information about Tritrichomonas foetus
When evaluating feline patients with diarrhea it is essential to include infectious etiologies on the list of differential diagnoses. One such infectious organism is Tritrichomonas foetus, a flagellated protozoal parasite that is usually associated with venereal trichomoniasis in cattle. Recently, T. foetus has also been identified as an intestinal pathogen in cats. Diarrhea has been reported in cats after both experimental and natural infection. Although the true prevalence of T. foetus infection in cats is unknown, it is suspected to be relatively high. In one study, 31% of 117 cats examined at an international cat show were found to be infected with T. foetus.
While cats of any age, breed, or sex can be infected, young cats that are densely housed (e.g., cats in catteries, animal shelters, or multi-cat households) seem to be at increased risk. Infection is most commonly seen in young cats (i.e., those that are less than 12 months of age) but older cats may also be infected. T. foetus primarily colonizes the surface of the colonic mucosa, leading to chronic large bowel diarrhea. Without appropriate treatment cats usually remain persistently infected. While diarrhea may spontaneously resolve, cats will often experience recurrent bouts of diarrhea after being exposed to stress. Cats infected with T. foetus generally appear healthy but show an increased frequency of defecation with loose to liquid stools, which may contain blood and/or mucus. Fecal incontinence is frequently observed. The anal region often appears edematous and may become painful with severe diarrhea. A rectal prolapse may occur in some cases.
Who should be tested?
In general, kittens and young cats from multi-cat environments with chronic diarrhea should be tested for Tritrichomonas foetus infection. We especially recommend testing cats with an incomplete response to standard antibiotic treatment (e.g., tylosin or metronidazole) or with a relapse after discontinuation of medication. Furthermore, cats that are unresponsive to treatment for suspected Giardia spp. infection should be tested, as the two parasites are very often confused on routine fecal smear evaluation.
Diagnosis
Diagnosis of a T. foetus infection can be made by identification of trophozoites on a direct fecal smear examination, fecal culture, PCR analysis of fecal material, or by colonic mucosal biopsy. Disadvantages of direct fecal smear examination include a low sensitivity (14%), low specificity (T. foetus can be misdiagnosed as Giardia spp. or the nonpathogenic Pentatrichomonas hominis), and the fact that only fresh fecal samples can be used.
Tritrichomonas foetus can also be cultured in-house using the commercially available culture system In Pouch™ TF (Biomed Diagnostics, San Jose, CA). Pouches should be inoculated with less than 0.1 g of freshly voided feces and then incubated at 25°C. Pouches need to be evaluated under a microscope every couple of days. Results are usually obtained between 1 and 11 days of setting up a pouch. Although fecal culture is more sensitive than direct fecal smear examination, difficulties in interpretation of results, the necessity of using freshly voided feces, and the fact that results might not be available for up to 11 days, are important disadvantages of this method.
T. foetus DNA can be amplified from fecal samples by PCR. PCR has been shown to be the most sensitive method for detecting T. foetus in fecal samples, and is ideally suited for direct diagnosis of T. foetus infection. Advantages of PCR testing compared to culture include a higher sensitivity, faster turnaround time, and easier handling and storing of samples because DNA is relatively stable under various temperature conditions.
Therapy
Until recently, a successful treatment strategy for Tritrichomonas foetus infections in cats was not available. However, a recent study has shown that administration of ronidazole (30 mg/kg PO twice daily for two weeks) is effective in both resolving diarrhea and eradicating T. foetus.
Recently, several compounding pharmacies have started offering ronidazole. Some examples are Diamondback Drugs (phone: 1-866-646-2223; www.diamondbackdrugs.com), Pet Health Pharmacy (phone: 1-800-742-0516), Abrams Royal Pharmacy (phone: 1-800-458-0804), Westlab Pharmacy (phone: 1-800-493-7852), and Creative Compounding (phone: 1-800-672-2177), but other compounding pharmacies may also carry ronidazole.
References
1. Foster DM, Gookin JL, Poore MF, et al. Outcome of cats with diarrhea and Tritrichomonas foetus infection. JAVMA 2004; 225:888-892.
2. Gookin JL, Stebbins ME, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and giardia infection. J Clin Microbiol 2004; 42:2707-2710.
3. Gookin JL, Birkenheuer AJ, et al. Single-tube nested PCR for detection of Tritrichomonas foetus in feline feces. J Clin Microbiol 2002; 40:4126-4130.
4. Gookin JL, Copple CN, Papich MG, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. JVIM 2006; 20:536-543.
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