Comparison of growth rates of Tritrichomonas foetus isolates from various geographic regions using three different culture media

Unexpected Cross-Reaction with Honigbergiella-Like DNA in a PCR for Detection of Bovine Tritrichomonas foetus

The prevalence of bovine Tritrichomonas foetus infection has decreased almost to zero in most European countries, such as Poland, which has been Tritrichomonas foetus-free since 1997. However, trichomonosis is a notifiable disease and there is a duty to examine samples from cattle. In this study, we present an unexpected cross-reaction with Honigbergiella-like DNA in a specimen from a bull. The bovine sample was submitted to the Department of Parasitology National Veterinary Research Institute in Pulawy (NVRI) for confirmatory testing after having been examined at the Regional Veterinary Laboratory, during a routine T. foetus diagnosis. Positive results from microscopic observation and cultures were confirmed. Noteworthily, parasites grew on Diamond’s medium only after seven days of incubation, while optimal growth of trichomonads is generally observed after two to four days for this medium. Moreover, by using PCR we obtained positive results for the presence of T. foetus. However, sequencing of the amplification product revealed 99.62% identity with Honigbergiella sp. Our data suggest that false-positive results may occur in commonly used PCR tests. Thus, unexpected results should be carefully interpreted.

Addressing the constraints of Tritrichomonas foetus sample collection in remote areas: lyophilized modified Diamond's media as a substitute for liquid medium

Bovine trichomoniasis is a notifiable, reproductive disease of cattle caused by the parasite Tritrichomonas foetus. Culturing with modified Diamond's medium (MDM) is required to increase the low number of organisms received from a preputial sample, but is limited in application to remote areas as it requires continuous cold chain storage. This study utilized lyophilization to sustain the viability of MDM during transport in lieu of a continuous cold chain. All lyophilized MDM was able to sustain T. foetus after storage for 42 days at 24 °C, and the results demonstrated that lyophilized MDM was equally as viable as refrigerated liquid MDM. Storage of lyophilized MDM at room temperature for 1 and 7 days did not impact T. foetus yield, both with and without exposure to light. A limitation of the lyophilized MDM was demonstrated with a significant decrease in T. foetus yield when the media was stored at 37 and 58 °C. The lyophilization of MDM provides a robust method of transporting and storing medium prior to reconstitution and inoculation, for use in T. foetus diagnosis and surveillance in remote areas.

Trichomonas

The most widely known trichomonad in veterinary medicine is Tritrichomonas foetus. It is the etiologic agent of bovine tritrichomonosis, a sexually transmitted disease in extensively managed herds throughout many geographic regions worldwide. The same trichomonad species is also regarded as the causative agent of chronic diarrhea in the domestic cat, although more recent studies observed molecular differences between bovine- and feline-derived T. foetus. Trichomonosis in cats has a worldwide distribution and is mainly present among cats from high-density housing environments. Other trichomonads are found as inhabitants of the gastrointestinal tract in birds, such as Trichomonas gallinae. Particularly, Columbiformes, Falconiformes, Strigiformes, and wild Passeriformes can be severely affected by avian trichomonads. Diagnosis of trichomonosis is often complicated by the fragility of the parasite. To ensure valid test results, it is essential to collect and handle specimens in the right way prior to analysis. Cultivation tests, the specific amplification of parasites, or a combination of both test methods is the most efficient and most commonly used way to diagnose trichomonosis in animals. Bovine tritrichomonosis is mainly controlled by the identification and withdrawal of infected animals from bovine herds. The control of feline and avian trichomonosis relies mainly on preventive measures.

A review of sexually transmitted bovine trichomoniasis and campylobacteriosis affecting cattle reproductive health

The objective is to discuss sexually transmitted diseases caused by Tritrichomonas foetus (T foetus) and Campylobacter fetus (C fetus) subsp. venerealis, with a focus on prevalence, pathogenesis, and diagnosis in cows and bulls. Diagnosis and control are problematic because these diseases cause severe reproductive losses in cows, but in bulls are clinically asymptomatic, which allows the disease to flourish, especially in the absence of legislated control programs. We review research regarding prophylactic systemic immunization of bulls and cows with antigens of T foetus and C fetus venerealis and their efficacy in preventing or clearing preexisting infections in the genital tract. Current diagnostic methods of C fetus venerealis and T foetus (microbial culture and PCR) should be improved. Review of the latest advances in bovine trichomoniasis and campylobacteriosis should promote knowledge and provide an impetus to pursue further efforts to control bovine sexually transmitted diseases.

Host origin determines pH tolerance of Tritrichomonas foetus isolates from the feline gastrointestinal and bovine urogenital tracts

The ability for protozoan parasites to tolerate pH fluctuations within their niche is critical for the establishment of infection and require the parasite to be capable of adapting to a distinct pH range. We used two host adapted Tritrichomonas foetus isolates, capable of infecting either the digestive tract (pH 5.3-6.6) of feline hosts or the reproductive tract (pH 7.4-7.8) of bovine hosts to address their adaptability to changing pH. Using flow cytometry, we investigated the pH tolerance of the bovine and feline T. foetus isolates over a range of physiologically relevant pH in vitro. Following exposure to mild acid stress (pH 6), the bovine T. foetus isolates showed a significant decrease in cell viability and increased cytoplasmic granularity (p-value < 0.003, p-value < 0.0002) compared to pH 7 and 8 (p-value > 0.7). In contrast, the feline genotype displayed an enhanced capacity to maintain cell morphology and viability (p-value > 0.05). Microscopic assessment revealed that following exposure to a weak acidic stress (pH 6), the bovine T. foetus transformed into rounded parasites with extended cell volumes and displays a decrease in viability. The higher tolerance for acidic extracellular environment of the feline isolate compared to the bovine isolate suggests that pH could be a critical factor in regulating T. foetus infections and host-specificity.

Loop mediated isothermal amplification of 5.8S rDNA for specific detection of Tritrichomonas foetus

Tritrichomonas foetus is the causative agent of bovine trichomonosis, a sexually transmitted disease leading to infertility and abortion. A test based on loop mediated isothermal amplification (LAMP) targeting the 5.8S rDNA subunit was designed for the specific identification of T. foetus. The LAMP assay was validated using 28 T. foetus and 35 non-T. foetus trichomonads strains. It did not exhibit cross-reaction with closely related parasites commonly found in smegma cultures like Tetratrichomonas spp. and Pentatrichomonas hominis. Bovine smegma did not show interferences for the detection of the parasite and, the sensitivity of the method (4 × 10³ CFU/mL, approximately 10 cells/reaction) was slightly higher than that found for PCR amplification with TFR3 and TFR4 primers. The LAMP approach has potential applications for diagnosis and control of T. foetus and, practical use for low skill operators in rural areas.

Canada and veterinary parasitology

A World Association for the Advancement of Veterinary Parasitology tradition for its conference is to present some highlights of the country hosting the event, and with an emphasis on the history of, and research in, veterinary parasitology. A review of Canada's peoples, physiography, climate, natural resources, agriculture, animal populations, pioneers in veterinary parasitology, research accomplishments by other veterinary parasitologists, centres for research in veterinary parasitology, and major current research had been presented at a World Association for the Advancement of Veterinary Parasitology Conference in Canada in 1987, and was published. The present paper updates the information on the above topics for the 22 years since this conference was last held in Canada.

Improved detection of Tritrichomonas foetus in bovine diagnostic specimens using a novel probe-based real time PCR assay

A Tritrichomonas foetus-specific 5' Taq nuclease assay using a 3' minor groove binder-DNA probe (TaqMan MGB) targeting conserved regions of the internal transcribed spacer-1 (ITS-1) was developed and compared to established diagnostic procedures. Specificity of the assay was evaluated using bovine venereal microflora and a range of related trichomonad species. Assay sensitivity was evaluated with log(10) dilutions of known numbers of cells, and compared to that for microscopy following culture (InPouch TF test kit) and the conventional TFR3-TFR4 PCR assay. The 5' Taq nuclease assay detected a single cell per assay from smegma or mucus which was 2500-fold or 250-fold more sensitive than microscopy following selective culture from smegma or mucus respectively, and 500-fold more sensitive than culture followed by conventional PCR assay. The sensitivity of the conventional PCR assay was comparable to the 5' Taq nuclease assay when testing purified DNA extracted from clinical specimens, whereas the 5' Taq nuclease assay sensitivity improved using crude cell lysates, which were not suitable as template for the conventional PCR assay. Urine was evaluated as a diagnostic specimen providing improved and equivalent levels of T. foetus detection in spiked urine by both microscopy following culture and direct 5' Taq nuclease detection, respectively, compared with smegma and mucus, however inconclusive results were obtained with urine samples from the field study. Diagnostic specimens (n=159) were collected from herds with culture positive animals and of the 14 animals positive by 5' Taq nuclease assay, 3 were confirmed by selective culture/microscopy detection (Fisher's exact test P<0.001). The 5' Taq nuclease assay described here demonstrated superior sensitivity to traditional culture/microscopy and offers advantages over the application of conventional PCR for the detection of T. foetus in clinical samples.

Bayesian estimation of Tritrichomonas foetus diagnostic test sensitivity and specificity in range beef bulls

Accuracy of culture for diagnosis of Tritrichomonas foetus was investigated in 2832 naturally exposed range beef bulls from 124 herds. Preputial fluid samples were inoculated into the culture medium, incubated at 37 degrees C, and daily examined. Diagnostic test was evaluated using Bayesian techniques to estimate sensitivity and specificity without a gold standard. Median posterior test sensitivity was 72.04% (95% probability interval: 58.07-86.38%) and specificity was 95.37% (95% probability interval: 94.07-96.65%). Low diagnostic test accuracy may have resulted from host and/or diagnostic test procedure related factors. Under natural range conditions, more accurate methods for T. foetus diagnostic and repeated preputial samplings of bulls may be necessary on trichomonosis control programs.

Are Tritrichomonas foetus and Tritrichomonas suis synonyms?

Tritrichomonas suis, a tritrichomonad of pigs, and the related species Tritrichomonas foetus, a tritrichomonad of cattle, are morphologically identical. The taxonomic relationship between these two tritrichomonads has been questioned ever since they were established as distinct species in 1843 and 1928, respectively. Here, we compare the similarities of morphology, ultrastructure, distribution, host specificity, characteristics of in vitro cultivation, immunology, biochemistry and analysis of molecular data from published sources between these two species. All data indicate that these two tritrichomonad species are identical. Thus, we propose that T. foetus and T. suis are synonyms.

Intra-strain clonal phenotypic variation of Tritrichomonas foetus is related to the cytotoxicity exerted by the parasite to cultured cells

As observed in most of the investigated trichomonads, a strain of Tritrichomonas foetus includes different parasite subpopulations. Such population diversity might account for important properties such as the ability of the parasite to destroy host cells. The aim of this study was to characterize the cytotoxicity exerted by subpopulations (named as K1, K2, K3, K4 and K5) of an isolate of T. foetus on epithelial cultured cells. The five populations studied here destroyed epithelial monolayers at different rates (from 25% to 55%), even though the cytoadhesion level and whole-cell protease activity were closely related among them. We were also able to detect differences in contact-dependent and contact-independent cytotoxicity mechanisms among the five populations. An extracellular parasite protease had varying activity among the parasite populations. The intensity of contact-independent cytotoxicity was strictly related to the degree of enzyme activation, suggesting that such a protease might be involved in the cytotoxicity mediated by T. foetus.

Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats

OBJECTIVE

To evaluate the efficacy of and optimize a commercially available culture system for sensitive and specific in-clinic culture of Tritrichomonas foetus from cat feces.

DESIGN

Prospective study.

SAMPLE POPULATION

Samples of freshly voided feces from 117 purebred cats and pure cultures of T. foetus obtained from a cat with chronic diarrhea.

PROCEDURE

Optimal conditions for use of the culture system, such as quantity of fecal inoculum (0.025 to 0.2 g) and cultivation temperature (25 or 37 degrees C [98.6 or 77.0 degrees F]), were determined. Specificity of the system was examined by attempted culture of Giardia lamblia and Pentatrichomonas hominis. Sensitivity of the system to detect T. foetus was determined by inoculation of culture system pouches with serially diluted T. foetus suspensions with and without feces.

RESULTS

Detection limit of the culture system was 1 and 1,000 T. foetus organisms without and with feces from cats, respectively. Optimal fecal inoculum was < 0.1 g of feces. At 37 degrees C, cultures yielded positive results in 24 hours; organisms remained viable for 1 to 6 days, and bacterial overgrowth was common. At 25 degrees C, cultures yielded positive results in 1 to 11 days; organisms were long-lived, and bacterial overgrowth was uncommon. Neither G. lamblia or P. hominis survived in the culture system.

CONCLUSIONS AND CLINICAL RELEVANCE

The culture system was sensitive and specific for culture of T. foetus in feces of cats. Performance was optimal when test kits were inoculated with < or = 0.1 g of freshly voided feces and cultured at 25 degrees C.