Time to take aim at treating trichomoniasis
While trichomoniasis is the most common curable sexually transmitted disease (STD) in the United States,1 reports of metronidazole-resistant trichomoniasis are increasing. New evidence indicates that tinidazole (Tindamax, Presutti Laboratories, Rolling Meadows, IL), recently introduced in the United States, is an effective therapy for metronidazole-resistant trichomoniasis and is well tolerated even at high doses.2
While metronidazole (Watson Pharmaceuticals, Corona, CA; Flagyl, GD Searle, Chicago) has served as an effective treatment for most people infected with Trichomonas vaginalis, the existence of drug-resistant infections is becoming increasingly recognized. What are some of the possible reasons for Trichomonas resistance?
"The answer is simply that we do not know or have good hypothesis about this phenomena yet," says Evan Secor, PhD, a microbiologist with the Centers for Disease Control and Prevention’s (CDC) Division of Parasitic Diseases.
"What is known about trichomonas resistance is based on studies done in the lab, and it turns out the clinical strains — or strains in nature — have different mechanisms for resistance and therefore make it difficult to transfer the lab-based knowledge to the clinical setting."
Combating trichomoniasis is an important objective in stemming STD infection, as it is associated with potentially serious complications such as preterm birth and HIV acquisition and transmission.3
The CDC regimen for metronidazole treatment of trichomoniasis calls for oral administration of 2 g in a single dose.4 If treatment failure occurs, the CDC recommends a re-treatment regimen of 500 mg twice a day for seven days. If treatment failure occurs repeatedly, patients should be treated with a single 2 g dose of metronidazole once a day for three to five days.4
In the new study, investigators from the CDC, Emory University in Atlanta, State University of New York in Brooklyn, and the University of Alabama at Birmingham (UAB) treated nine patients who had trichomoniasis that had resisted two courses of high-dose metronidazole therapy. Treatment consisted of 1 g oral Tindamax and 500 mg intravaginally twice daily. One patient was treated three times daily.
The Tindamax therapy yielded an 88% cure rate. Researchers also found that despite the high doses used, patient tolerance was good, with all patients completing therapy. In addition, the minimum lethal concentration (MLC) of Tindamax — the least amount needed to kill the trichomonads that cause the infection — was found to be consistently four to six times lower than the MLC for metronidazole, investigators note. Tindamax was approved by the Food and Drug Administration in 2004 as a treatment option for trichomoniasis.
"Tinidazole may be a better option as it is more active against trichomonas and better tolerated by patients," observes Jane Schwebke, MD, professor of medicine in the division of infectious diseases at UAB. Schwebke served as one of the investigators for the new research.
Trichomoniasis may go undetected, since women and men may show no signs of infection. Signs of trichomoniasis in women can include a yellow, gray, or green frothy vaginal discharge, often accompanied by a foul odor, with burning, itching, soreness, and redness of the vulva or vagina often present. Symptoms in men may include urethral discharge and irritation.
While in-office vaginal wet mounts often are used to diagnose trichomonas infection in women, laboratory tests must be used to detect infection in men. While culture remains the gold standard for detecting trichomoniasis, researchers are looking at DNA amplification techniques as a testing option.5
According to a 2003 review of existing research on trichomoniasis, further research should focus on developing effective partner treatment strategies to prevent re-injections and reduce trichomoniasis prevalence.6
References
1. Cates W. Estimates of the incidence and prevalence of sexually transmitted diseases in the United States. Sex Transm Dis 1999; 26(suppl):S2-S7.
2. Workowski KA, Mosure D, McCormack W, et al. Treatment of metronidazole resistant trichomoniasis with tinidazole. Abstract 815. Presented at the Infectious Diseases Society of America 2004 Annual Meeting. Boston, Sept. 30-Oct. 3, 2004.
3. Schwebke JR, Burgess D. Trichomoniasis. Clin Microbiol Rev 2004; 17:794-803.
4. Centers for Disease Control and Prevention. Sexually Transmitted Diseases Treatment Guidelines — 2002. MMWR 2002; 51(RR06):1-80.
5. Schwebke JR, Hook EW 3rd. High rates of Trichomonas vaginalis among men attending a sexually transmitted diseases clinic: Implications for screening and urethritis management. J Infect Dis 2003; 188:465-468.
6. Forna F, Gülmezoglu AM. Interventions for treating trichomoniasis in women. The Cochrane Database of Systematic Reviews 2003; Issue 2. Art. No. CD000218.
While trichomoniasis is the most common curable sexually transmitted disease (STD) in the United States,1 reports of metronidazole-resistant trichomoniasis are increasing. New evidence indicates that tinidazole (Tindamax, Presutti Laboratories, Rolling Meadows, IL), recently introduced in the United States, is an effective therapy for metronidazole-resistant trichomoniasis and is well tolerated even at high doses.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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