Trichomonas Infection — It's Not Just a Girl Thing, But the Guys Don't Know It
Abstract & Commentary
By Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor for Infectious Disease Alert.
Source: Seña AC, et al. Trichomonas vaginalis infection in male sexual partners: implications for diagnosis, treatment, and prevention. Clin Infect Dis. 2007;44:13-22.
Synopsis: Using multiple testing modalities, including a sensitive PCR, it was found that almost three-fourths of male sexual partners of women with vaginal trichomoniasis were also infected with this protozoan.
Male sexual partners of women with vaginal trichomoniasis were tested, using urethral and urine culture, as well as urine polymerase chain reaction (PCR), for evidence of infection with this flagellated protozoan. Approximately one-fourth of the women were asymptomatic, but one-half also had Gram stain evidence of bacterial vaginosis; 1.4% of those tested were HIV positive.
At least one of the 3 tests was positive in 177 of 256 (71.7%) of the male sex partners from whom samples were obtained, with PCR being the most sensitive. Only 41 (23.2%) of those with a positive test were symptomatic. Approximately 10% were co-infected with either Chlamydia trachomatis or Neisseria gonorrhoeae. None of the 69 tested were HIV infected. In multivariate analysis, a vaginal pH > 4.5 and younger male age were each independently associated with an increased risk of concordant trichomoniasis.
Commentary
Trichomoniasis is the most common non-viral sexually transmitted infection throughout the world. Evidence indicates that infection with Trichomonas vaginalis is not a trivial issue. Vaginal trichomoniasis appears to be associated with an increased risk of acquisition of HIV infection, as well as with complications such as pelvic inflammatory disease, and with adverse pregnancy outcomes. While most symptomatic cases occur in women, infection has been known to be common in their male (as well as female) sexual partners. Infection in men is, however, more frequently than not asymptomatic. As a whole, the available information suggests that consideration should be given to the development of public health programs designed to screen asymptomatic individuals, both male and female, for evidence of trichomonal infection.
Symptomatic women complain of vaginal discharge and vulvar irritation and most characteristically have a diffuse, yellow-green malodorous discharge. Men who are symptomatic have urethritis. The classical means of diagnosis in women is microscopic examination of vaginal secretions, but, relative to culture, this procedure has a sensitivity of only 60% to 70% — and is even less effective in the diagnosis of trichomonal urethritis in men. At least 2 rapid point-of-care tests, each of which has a reported sensitivity > 83% and specificity >97% relative to culture, have received FDA approval in the United States. One, an immunochromatographic capillary flow dipstick test (OSOM Trichomonas Rapid Test, Genzyme Diagnostics, Cambridge, Massachusetts) can provide results in 10 minutes, while the Affirm™ VP III, a nucleic acid probe test, requires 45 minutes.1 No commercial nucleic acid amplification test is available in the United States. Culture on media, such as Diamond's TYM, is usually positive within 48 hours, but requires 7 -10 days of incubation before the culture can be deemed to be negative.
The CDC recommends treatment with either metronidazole or tinidazole — there are no proven effective alternatives to the use of nitroimidazoles.1 The preferred regimens are a single 2-gram dose of either drug, while an alternative regimen is 500 mg metronidazole twice daily for 7 days. Topical formulations of metronidazole achieve cure rates of only approximately 50%. Sexual partners should also be treated. Follow-up is not necessary in patients whose symptoms resolve. However, low-level resistance to metronidazole occurs in 2% to 5% of cases, and high-level resistance has also been reported. If symptomatic infection persists after treatment with metronidazole and the sexual partners have also been treated, the 5-day bid course of metronidazole or a single dose of tinidazole can be used. If both of these fail, the CDC recommends giving either drug in a dose of 2 grams daily for 5 days. The CDC offers in vitro susceptibility testing for selected isolates.
Reference
- CDC. Sexually transmitted diseases treatment guidelines, 2006. MMWR. 2006; 55(RR11); 1-94. www.cdc.gov. Accessed Jan. 7, 2007.
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