OVERVIEW: What every practitioner needs to know about Trichomonas vaginitis

Are you sure your patient has disease Trichomonas vaginitis? What should you expect to find?

  • At least half the women with vaginal trichomoniasis are asymptomatic.

    Newer tests for diagnosis of trichomonas reveal that this condition is frequently missed both as an asymptomatic infection as well as when patients present with symptoms.

  • Consider in women with a malodorous, copious discharge together with signs of florid vulvovaginitis.

    Continue Reading

What laboratory studies should you order and what should you expect to find?

Results consistent with the diagnosis

  • Vaginal pH is always elevated in vaginal trichomoniasis in excess of 5.

  • As with BV, a positive amine test is common

    Probably reflects the fact that about 70% of women with vaginal trichomoniasis have a mixed infection with BV.

  • Almost always accompanied by increase in PMNs

  • Also accompanied by a disruption in the normal vaginal flora (microbiota).

Results that confirm the diagnosis

  • Microsopic exam

    even in the hands of experienced microscopists the sensitivity of this test in identifying trichomoniasis limited is only approximately 50%.

  • Swab for culture planted on Diamond’s media

    this culture is not widely obtained

    its sensitivity is now surpassed by newer PCR techniques.

  • OSOM-Trichomonas® test is now available as a point-of-care test with reasonable sensitivity of 80-85%, not as sensitive as polymerase chain reaction (PCR), but it provides an answer within minutes.

  • The Affirm® test is a DNA probe without PCR which similarly can provide results within a few hours, sensitivity is approximately 10-20% below PCR

  • PCR testing for trichomonas is now widely available and the preferred test with regards to sensitivity.

    many commercial laboratories offer a PCR test

    Aptima-trichomonas (Gen-Probe) is the only FDA approved PCR test

What consult service or services would be helpful for making the diagnosis and assisting with treatment?

Usually there is no need for a consultant.

If you decide the patient has Trichomonas vaginitis, what therapies should you initiate immediately?

Key principles of therapy:

  • Oral metronidazole is the treatment of choice according to the CDC Guidelines remains

    500mg bid for 7 days


    single dose of 2.0g.

  • Cure rates are extremely high.

  • Alternatives to oral metronidazole:

    Tinidazole (tindamax) has slightly enhanced in vitro activity against trichomonas

    more expensive and does not appear to offer superior cure rates in most patients.

    Vaginal metronidazole gel as currently formulated in the U.S. contains low doses of metronidazole, should not be used to treat vaginal trichomoniasis.

  • Issue of resistance to metronidazole-treated trichomoniasis:

    Most patients with recurrent trichomoniasis occur as the result of failure to treat a sexual partner

    the standard of care requires mandatory treatment of male partners

    requires initial abstinence

    then requires use of condom.

    Between 3-5% of women with vaginal trichomoniasis will have low level metronidazole resistance.

    Most of these patients can be effectively treated by a second course of divided dose oral metronidazole 500mg bid for 7 days.

    If the patient has high levels of metronidazole resistance, occurs in less than 1% of patients

    tinidazole becomes the drug of choice.

    give at a higher total dose of 7-14gm, (1-2g daily).

    some experts use even higher doses of tinidazole including a higher dose of 2gm per day for 14 day regimen.

    can add intravaginal oral tablets of metronidazole over that same period reaching total doses in excess of 42gm.

    rarely combination therapy consisting of high dose oral tinidazole together with vaginal paramomycin may be needed to treat these rare high resistant organisms.

What complications could arise as a consequence of trichomoniasis?

Both asymptomatic and symptomatic disease are considered risk factors for:

  • Pelvic inflammatory disease

  • HIV transmission

  • Preterm labor

How do you contract Trichomoniasis?

  • Sexually transmitted and is most frequently seen in women in STD clinics.

    Any woman with a history of high-risk behavior including multiple sexual partners should be tested for trichomoniasis as well as for chlamydia, gonorrhea (GC) and HIV.

    Its frequency now exceeds that of chlamydia and GC infections.

    It peaks in young sexually active adolescent women as well as women in their third decade of life; however, a second smaller peak is often seen in post-menopausal women.

WHAT'S THE EVIDENCE for specific management and treatment recommendations?

Anderson, MR, Klink, K, Cohrssen, A. “Evaluation of vaginal complaints”. JAMA. vol. 291. 2004. pp. 1368(common sense approach to evaluating symptoms of vulvovaginitis.)

McClelland, RS, Sangare, L, Hassan, WM. “Infection with Trichomonas vaginalis increases the risk of HIV-1 acquisition”. J Infect Dis. vol. 195. 2007. pp. 698(Important study linking infection with Trichomonas to increased risk for developing HIV infection.)

Schwebke, JR, Barrientes, FJ. “Prevalence of Trichomonas vaginalis isolates with resistance to metronidazole and tinidazole”. Antimicrob Agents Chemother. vol. 50. 2006. pp. 4209(Resistance to these agents is rare, but does occur.)

Schwebke, JR, Hobbs, MM, Taylor, SN, Sena, AC, Catania, MG, Weinbaum, BS, Johnson, AD, Getman, DK, Gaydos, CA. “Molecular testing for Trichomonas vaginalis in women: results from a prospective U.S. clinical trial”. J Clin Microbiol. vol. 49. 2011. pp. 4106-11. (Molecular testing has now become the preferred test for diagnosis because of higher sensitivity than older methods, such as microscopy.)

Sobel, JD, Nyirjesy, P, Brown, W. “Tinidazole therapy for metronidazole-resistant vaginal trichomoniasis”. Clin Infect Dis. vol. 33. 2001. pp. 1341(Shows the benefit of tinidazole when metronidazole is ineffective.)

Soper, D. “Trichomoniasis: under control or undercontrolled”. Am J Obstet Gynecol. vol. 190. 2004. pp. 281

Workowski, KA, Berman, S. “Centers for Disease Control and Prevention (CDC): Sexually transmitted diseases treatment guidelines, 2010”. MMWR Recomm Rep. vol. 59. 2010. pp. 1(Updated Guidelines from the CDC which guide treatment for sexually transmitted infections.)