''Trichomonas tenax'', or oral trichomonas, is a species of ''

Trichomonas ''Trichomonas'' is a genus of anaerobic excavate parasites of vertebrates. It was first discovered by Alfred François Donné in 1836 when he found these parasites in the pus of a patient suffering from vaginitis, an inflammation of the vagina ...

'' commonly found in the oral cavity of humans. Routine hygiene is generally not sufficient to eliminate the parasite, hence its Latin name, meaning "tenacious". The parasite is frequently encountered in periodontal infections, affecting more than 50% of the population in some areas, but it is usually considered insignificant. ''T. tenax'' is generally not found on the gums of healthy patients. It is known to play a pathogenic role in necrotizing ulcerative gingivitis and necrotizing ulcerative periodontitis, worsening preexisting periodontal disease. This parasite is also implicated in some chronic lung diseases; in such cases, removal of the parasite is sufficient to allow recovery (Mussaev 1976).

Morphology

Of the three species in the genus ''Trichomonas'', ''T. tenax'' is the smallest, measuring only 5-14 µm long and 6-9 µm wide; specimens can be identified by their long axostyles and tails, 4 anterior flagella, and by the recurrent flagellum that raises an undulating membrane which is two thirds the length of the body. This undulating membrane may appear like small legs. It may occasionally appear larger, allowing it to be confused with ''Trichomonas vaginalis'' due to similar morphology. In such cases, the presence of an oral or vaginal parasite should be confirmed, due to the ease with which the parasite can be transmitted through direct contact of mucous membranes.

Life cycle

''T. tenax'' trophozoites survive in the body as mouth scavengers that feed primarily on local microorganisms located between the teeth, tonsillar crypts, pyorrheal pockets, and the gingival margin around the gums. ''T. tenax'' trophozoites multiply by longitudinal binary fission. These trophozoites are unable to survive the digestive process.

Clinical

Transmission

''T. tenax'' is a commensal of the human oral cavity, found particularly in the patients with poor oral hygiene and advanced

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main cau ...

. Transmission is through saliva, droplet spray, and kissing or use of contaminated dishes or drinking water.

Signs and symptoms

''T. tenax'' alone is not known to cause any symptoms. There are merely implications that this parasite may worsen preexisting periodontal disease and in rare cases has been reported to cause bronchopulmonary infections, mainly in patients with underlying cancers or other lung diseases. The organism is believed to enter the respiratory tract by aspiration from the oropharynx.

Mechanism

In infected hosts, the parasite can typically be found among dental calculus, as well as within the tonsillar crypts, which will often become purulent during the course of infection. ''T. tenax'' may also be involved in the degradation of periodontal tissue through the secretion of substances such as alkaline phosphatases and the

fibronectin Fibronectin is a high-molecular weight (~500-~600 kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Fibronectin also binds to other extracellular matrix proteins such as collagen ...

cathepsin Cathepsins (Ancient Greek ''kata-'' "down" and ''hepsein'' "boil"; abbreviated CTS) are proteases ( enzymes that degrade proteins) found in all animals as well as other organisms. There are approximately a dozen members of this family, which are d ...

e. ''T. tenax'' is classified as a parasite due to the manner in which it causes damage to host tissues; its behavior when in contact with target cells is similar to the closely related and likewise parasitic ''T. vaginalis''. It has no cysts and is only transmitted directly in its vegetative form.

Diagnosis

The specimen of choice for diagnosing ''Trichomonas tenax'' trophozoite is mouth scrapings. Microscopic examination of tonsillar crypts and pyorrheal pockets of patients with ''T. tenax'' infections often yields the typical trophozoites. Tartar between the teeth and the gingival margin of the gums are the primary areas of the mouth that may also potentially harbor this organism. ''T. tenax'' may also be cultured onto appropriate media.

Treatment

Regardless of patient's demographic characteristics, it seems that oral hygiene instructions in combination with scaling and root planning can help with controlling excessive colonization of parasites, particularly ''E. gingivalis'' and ''T. tenax'' and their probable opportunistic infestation. ''T. tenax'' can easily be detected through the use of

phase-contrast microscopy __NOTOC__ Phase-contrast microscopy (PCM) is an optical microscopy technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image. Phase shifts themselves are invisible, but become visibl ...

. Biofilm harvested from infested areas of the periodontal pockets can be mounted onto a slide; ''T. tenax'', if present, will be clearly visible. The preparation must use the patient's saliva as the medium, as the use of plain water or saline as

hypotonic In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-i ...

solutions could cause the cells to lyse.

History

The etymology of the name ''Trichomonas tenax'' is from a combination of Greek: (tiny hair) + (simple creature), and Latin: (to keep, to stick to). During the early 1900s, prisoners at the San Quentin prison in California were subject to advanced periodontal disease at a rate of almost 90%, owing at least in part to a high rate of infection by ''T. tenax''. In the ''

Journal of the American Dental Association The ''Journal of the American Dental Association'' is a monthly peer-reviewed medical journal on dentistry published by the American Dental Association. It is freely available to the public after a one-year embargo. The journal was first published ...

'', it was speculated that this high rate of transmission was attributable to the crowding and poor diets faced by inmates. Age was also an important factor in this population and intense inflammation was observed.

Research directions

Owing to the morphological similarity between ''T. tenax'' and other trichomonad spp., examination of a greater number of organisms is necessary to establish a reliable diagnosis than is easily obtained from the patient's mouth. ''In vitro,'' ''T. tenax'' reproduced better in LES medium, pH value between 5.80 and 7.00 with cultivation temperature of 35 °C than other media with pH 5.40 and cultivation temperature of 37 °C. Normal, healthy human saliva is slightly alkaline at pH 7.40. Whitening products have a mean pH of 8.22 with a range (5.09-11.13). Whitening toothpastes have a mean pH of 6.83 with a range (4.22-8.35). Mouthwashes also vary greatly in pH from pH 4.40 to 6.80. Mouth rinsing after an acidic challenge increased salivary pH. The tested mouthwashes raised pH higher than water. Mouthwashes with a neutralizing effect can potentially reduce tooth erosion from acid exposure. Essentially the human mouth is an optimum habitat for this organism and any pH level alteration needed to stunt the reproductive rate significantly would require a duration of time that would cause greater damage to the tooth enamel than to ''T. tenax''. Regular oral hygiene and dental visits to remove dental plaque is currently the best solution to deal with this protozoan.

Other hosts

''T. tenax'' has been found in the mouths of a small proportion of dogs, cats and horses, but other animals are expected to have their own species of ''Trichomonas ''.