Infectious Disease

Coinfection of Trichomoniasis with Other Sexually Transmitted Infections

A 22-year-old Black female presents to your emergency department with a chief complaint of painful urination and intercourse, as well as post-coital bleeding.

Upon further questioning, you learn that this patient had unprotected sexual intercourse 2 weeks ago and has had 3 new, different sexual partners within the past 6 months. On pelvic examination, you notice whitish discharge along with vulvovaginal erythema. Rapid testing for Chlamydia and Gonorrhea (CT/NG) are ordered. Rapid testing for Trichomonas Vaginalis (TV) is unavailable, however. You decide to treat her empirically with 250 mg IM ceftriaxone and 1 g PO azithromycin.

Clinical Question: What is the prevalence of gonorrhea, chlamydia, and trichomonas co-infection rates, and if rapid testing for Trichomoniasis is unavailable in the ED, should the clinician empirically treat the patient for trichomonas given the patient's current presumed sexually transmitted infection (STI)?

Background and Overview

Trichomoniasis is a urogenital protozoan sexually transmitted infection. Its formal protozoan name is Trichomonas vaginalis, which also goes by T. vaginalis (TV)). It often manifests as vulvovaginitis in women or urethritis in men.1 Within the United States, it is considered to be the most common non-viral sexually transmitted infection (STI) with an annual incidence of 3-5 million cases.2 The reported prevalence was 1.8% among women in the US and 0.5% of men in the U.S.2 Trichomoniasis has the strongest prevalence in women who are older than 40 years of age, whereas other STIs like chlamydia (CT) and gonorrhea (NG) are lowest within this age group.3

The pathogenesis of trichomoniasis is not completely understood, but it is presumed that T. vaginalis comes in contact with an individual’s genital epithelial during sexual intercourse, facilitating the transmission from an infected individual to an uninfected individual. T. vaginalis is able to adhere to the epithelial surface and form aggregates and later erode through the epithelial layer to spread along other regions of the genitourinary tract. Sequela of trichomoniasis infection can include pelvic inflammatory disease, infertility, cervical neoplasia, pregnancy complications and an increased susceptibility of HIV transmission in women.4 Risk factors for contracting trichomoniasis include history of STI infections, new and/or multiple sexual partners, early onset of sexual intercourse, and intravenous drug use.3

Common chief complaints for women with this infection include vulvar pruritis, dysuria, odorous discharge, and/or postcoital bleeding. Men may have symptomatic complaints of dysuria, genital pruritis, or hematuria. However, it is very common for either gender to present asymptomatic and thus screening for the disease is very important. Diagnosis is performed through wet mount microscopy or molecular assays. Treatment is a recommended one-time dose of either metronidazole/tinidazole 2g PO or metronidazole 500 mg BID x 7 days. Patients should refrain from alcohol use while on the prescribed medications until 24 hours after completion to avoid a disulfiram-like reaction. Patients should also abstain from sexual intercourse until all partners have completed the treatment regimen and have full symptomatic resolution. Additionally, patients should receive follow-up testing between 2 weeks and 3 months of completing treatment. It is important for these patients to undergo additional STI testing at that time including further evaluation for HIV.

Epidemiology and Prevalence of Co-infection

Vaginalis is considered to be the neglected STI, as there is still a lack of established screening programs within the United States. There is also a relatively poor understanding of co-infection rates between trichomoniasis and other STIs. One study investigated the coinfection rates between CT and TV by collecting CT positive patient samples and performing molecular assays for TV. The study showed an overall CT/TV co-infection rate of 22%. The rates were even higher in black women ages 18-24.5 Several studies have demonstrated a significant racial disparity of TV infection, with TV being vastly more prevalent in non-Hispanic, Black women. One study cited a 10.3x higher rate than that among non-Hispanic Caucasian and Hispanic-American women.6

There has been a suggestive association of age and the prevalence of TV/CT or TV/NG coinfection. Trichomoniasis, alone, is unique in that it increases in prevalence with increasing age among women until age 50, at which point the prevalence plateaus. This is unlike the pattern demonstrated in the majority of other STIs.6 Chlamydia and gonorrhea, for example, show highest prevalence in the 15-29 age range and decrease in prevalence with increasing age.3

This contrast in prevalence between isolated TV and other isolated STIs is the reason why studies showed low rates of co-infection between TV/NG or TV/CT (<1.3%) when studying the whole population (combining young and older age groups).7 However, there is a paradoxical relationship in that although the prevalence of Trichomoniasis is lower in younger age groups, the prevalence of coinfections is highest in the younger age ranges. The same study done by Ginocchio and colleagues noted that coinfection of TV with CT or TV with NG were found to be more prevalent in women <30 years of age likely due to the increased prevalence of CT and NG in this younger demographic.7 Another study showed that the association between CT and TV coinfection was significant when categorizing for a higher risk age group (14-25) of contracting STIs.8

Another study published in 2002 investigated epidemiological features of female attendees at an STI clinic who had been diagnosed with TV infection. The study found that of those female patients, 28% had coexisting CT infection and 10% had coexisting NG infection.9 A separate study investigated the same correlation but in men attending a STI clinic. The study found that in men older than 30 years of age, the presence of discharge and non-gonococcal urethritis were independently predictive of a TV infection.10 This study suggested that empiric treatment and partner management should include the high likelihood of TV co-infection.10 Although the patient population at STI clinics do not represent the general population, the above studies do indicate a correlation between TV with concurrent CT or NG infection.


For many patients, the ED represents the primary access point for healthcare. The ED often serves patients at high risk for sexually transmitted infections who are either symptomatic or asymptomatic with presumed exposure. It is likely that patients are lost to follow up or unlikely to follow up with testing, making it even more important that the adequate treatment and diagnostic testing are provided.

In regard to trichomoniasis, there have been several studies indicating a significant prevalence of coinfection with CT or NG, when a patient is in the high risk age range (18-25) or is a non-Hispanic African American individual. Currently, there are no broad guidelines from the center for disease control (CDC), American College of Obstetrics and Gynecology (ACOG), American College of Emergency Physicians (ACEP) or Infectious Disease Society of America (IDSA) regarding empiric treatment of TV in patients presenting with concerns for STIs. The current treatment guidelines only recommend for empiric treatment of TV, NG, and CT infections for patients who are survivors of sexual assault due to poor compliance for follow up visits.

Nevertheless, based on prevalence/co-infection rates, physicians should consider empirically treating for TV in settings where rapid testing is unavailable. This is especially true in young adults or African American patients. In settings where rapid diagnostics are available, physicians should include TV testing when evaluating a patient for STIs. Empiric treatment covering TV can prevent long term sequelae and decrease the overall burden of transmission.

Case Conclusion

The patient was found to be positive for both CT and NG on the rapid testing. Given the patient’s high-risk profile, including her age and non-Hispanic black ethnicity, she was treated empirically to cover for TV. In addition to the 250 mg IM ceftriaxone and 1 g PO azithromycin she was given a single dose of 2 mg metronidazole. She was recommended to receive follow up testing for reinfection and to undergo further evaluation for other STIs in the ambulatory setting within 3 months and to inform her sexual partner(s) for treatment to avoid reinfection. Abstinence was recommended until completion of the treatment course and resolution of symptoms for both the patient and any affected sexual partner(s). The patient was also educated that contract tracing varies with the STI one is diagnosed with. Infections with chlamydia warrants informing all sexual partners one has had in the past 6 months prior to confirmed diagnosis, whereas gonorrhea is 2 months and trichomoniasis is unknown (other than treating the current/most recent sexual partner).


  1. DynaMed [Internet]. Ipswich (MA): EBSCO Information Services. 1995 - . Record No. T116226Trichomoniasis; [updated 2018 Nov 30, cited 2020 Oct 08 Available from
  2. Patel EU, Gaydos CA, Packman ZR, Quinn TC, Tobian AAR. Prevalence and Correlates of Trichomonas vaginalis Infection Among Men and Women in the United States. Clin Infect Dis. 2018 Jul 2;67(2):211-217. doi: 10.1093/cid/ciy079. PMID: 29554238; PMCID: PMC6031067.
  3. Workowski KA, Bolan GA, Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015 Jun 5;64(RR-03):1-137full-text, correction can be found in MMWR Recomm Rep 2015 Aug 28;64(33):924, commentary can be found in Ann Emerg Med 2015 Nov;66(5):527
  4. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins—Gynecology. Vaginitis in Nonpregnant Patients: ACOG Practice Bulletin, Number 215. Obstet Gynecol. 2020 Jan;135(1):e1-e17
  5. Kaul, Anil. (2018). Trichomonas vaginalis and Chlamydia trachomatis co-infections. Journal of Infectious Diseases & Therapy. 06. 10.4172/2332-0877-C2-040.
  6. Sutton M, Sternberg M, Koumans EH, McQuillan G, Berman S, Markowitz L. The prevalence of Trichomonas vaginalis infection among reproductive-age women in the United States, 2001-2004. Clin Infect Dis. 2007 Nov 15;45(10):1319-26. doi: 10.1086/522532. Epub 2007 Oct 15. PMID: 17968828.
  7. Ginocchio CC, Chapin K, Smith JS, et al. Prevalence of Trichomonas vaginalis and coinfection with Chlamydia trachomatis and Neisseria gonorrhoeae in the United States as determined by the Aptima Trichomonas vaginalis nucleic acid amplification assay. J Clin Microbiol. 2012;50(8):2601-2608. doi:10.1128/JCM.00748-12
  8. Allsworth JE, Ratner JA, Peipert JF. Trichomoniasis and other sexually transmitted infections: results from the 2001-2004 National Health and Nutrition Examination Surveys. Sex Transm Dis. 2009;36(12):738-744. doi:10.1097/OLQ.0b013e3181b38a4b
  9. Lo M, Reid M, Brokenshire M. Epidemiological features of women with trichomoniasis in Auckland sexual health clinics: 1998-99. N Z Med J. 2002 Aug 9;115(1159):U119. PMID: 12362164.
  10. Joyner JL, Douglas JM Jr, Ragsdale S, Foster M, Judson FN. Comparative prevalence of infection with Trichomonas vaginalis among men attending a sexually transmitted diseases clinic. Sex Transm Dis. 2000 Apr;27(4):236-40. doi: 10.1097/00007435-200004000-00010. PMID: 10782747.

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