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Sexually transmitted infections

Last updated: April 6, 2021

Summary

The term "sexually transmitted infections" (STIs) refers to a group of infections that are mainly transmitted via sexual intercourse. The most common symptoms of STIs are pain in the suprapubic and genital area, urethral or vaginal discharge, and genital lesions, which may or may not be painful. Some STIs (e.g., HPV) may induce or predispose to malignant changes. The majority of STIs are asymptomatic, and therefore easily spread. If a patient is already infected with an STI, they are predisposed to coinfections with further STIs. There are various treatment options for each STI, with simultaneous treatment of the partner often necessary to prevent recurrent infections. In some cases, health care providers are required by law to report cases of STIs to county and health state departments (e.g., HIV, hepatitis B).

Overview of sexually transmitted infections

Overview of sexually transmitted infections
Pathogens	Associated disease	Management
Viral pathogens
Human papillomavirus type 6 and 11	Condylomata acuminata Bowenoid papulosis (condylomata plana)	Local cytotoxic therapy (e.g., with 5-fluorouracil) Cryotherapy Operative management: curettage (surgical excision), laser surgery, or electrosurgery
Herpes simplex virus type 2 (HSV-2)	Genital herpes	Acyclovir PO for episodic or suppressive treatment
HIV	Opportunistic infections Lymphoma Kaposi sarcoma	Systemic antiretroviral therapy: HAART/cART
Hepatitis B virus (HBV)	Hepatitis B	Systemic antiviral therapy PO (e.g., entecavir) Interferon (immune-modulating, antiviral, and antiproliferative agent) injected SC or IM
Bacterial pathogens
Chlamydia trachomatis D–K	Urogenital chlamydia infections ♀: Urethritis, vulvovaginitis, cervicitis, salpingitis, tuboovarian abscess, pelvic inflammatory disease (PID), reactive arthritis ♂: Urethritis, epididymitis, reactive arthritis, prostatitis	Drug of choice: doxycycline OR azithromycin PO Alternative: fluoroquinolone (e.g., ciprofloxacin, moxifloxacin)
Chlamydia trachomatis L1–L3	Lymphogranuloma venereum
Klebsiella granulomatis	Granuloma inguinale
Haemophilus ducreyi	Chancroid	Ceftriaxone IM single dose Plus azithromycin PO single dose ^[1] Expedited partner therapy Cefixime PO (if chlamydia has been excluded in the patient) Cefixime PO PLUS doxycycline ^[2]
Neisseria gonorrhea	Gonorrhea ♀: Urethritis, salpingitis, tuboovarian abscess, pelvic inflammatory disease, cervicitis, Bartholin gland cyst ♂: Urethritis, epididymitis Viscous and purulent discharge Arthritis
Treponema pallidum	Syphilis	Penicillin G IM Alternatives if allergic to penicillin: tetracycline, macrolides, or cephalosporin
Parasitic pathogens
Trichomonas vaginalis	Trichomoniasis (cervicitis)	Metronidazole PO
Phthirus pubis	Pediculosis pubis (pubic lice, crab louse) Irritated skin in the pubic hair region Tiny brown lice droppings detectable	Permethrin 1% lotion (insecticide)

Genital lesions

Overview of genital lesions
Pathogen	Clinical features	Diagnosis
Painless lesions
Human papillomavirus type 6 and 11	Condylomata acuminata Single or multiple skin-colored 1–5 mm papular eruptions (genital warts) which can be smooth or verrucous Koilocytes Located on internal and external genitalia Bowenoid papulosis Single or multiple small papules (may coalesce into larger plaques) Pigmented with a flat-to-verrucous surface Most commonly on the penis shaft or external female genitals	Clinical exam and biopsy
Klebsiella granulomatis	Granuloma inguinale Large (5–10 mm), beefy-red, expanding suppurative ulcer Bleeds easily Often malodorous because of bacterial coinfection Commonly located in skin folds Regional lymph nodes typically spared	Clinical exam and biopsy (cytoplasmic Donovan bodies, bipolar staining)
Chlamydia trachomatis L1–L3	Lymphogranuloma venereum Transient, small papule, or shallow ulcer Rapid spontaneous healing without scarring ♂: foreskin, glans, and scrotum ♀: posterior vaginal wall, cervix, and vulva Possibly concurrent discharge, cervical/adnexal/testicular tenderness, and painful inguinal lymphadenopathy (may form buboes)	PCR detects Chlamydia trachomatis RNA or DNA
Treponema pallidum	Chancre Singular red, round, and raised ulcer with elevated edges Heals spontaneously within 4–8 weeks ♂: glans penis ♀: vulva and cervix Possibly concurrent regional adenopathy Condylomata lata Warty erosions on the genitals in the secondary phase of syphilis that are velvety, moist, and broad-based Resolve spontaneously after weeks to months	Darkfield microscopy (spirochetes) Serum antibody test
Painful lesions
Herpes simplex virus type 1 and 2 (mostly HSV-2)	Genital herpes Multiple grouped, vesicles (1–3 mm) on an erythematous ground Possibly concurrent malaise, myalgias, and fever Reactive painful inguinal lymphadenopathy common ♂: glans and penis shaft ♀: external female genitalia and cervix	Clinical exam Most accurate tests Viral culture of lesion PCR test of lesion Most rapid test: direct fluorescent antibody Confirmatory test: Tzanck smear (multinucleated giant cells)
Haemophilus ducreyi	Chancroid Single or multiple papules or pustules (10–20 mm) with yellowish-greyish exudate in the center ♂: glans penis, penis shaft, and scrotum ♀: vulva and perineal area Possibly concurrent painful inguinal lymphadenopathy and abscess formation	Clinical exam and culture
Trichomonas vaginalis	Vaginitis Erythematous and papilliform appearance of the cervix (strawberry cervix)	Motile trichomonads on wet mount examination

Anogenital warts (condylomata acuminata) Granuloma inguinale Granuloma inguinale (Donovaniosis) Chancre of the glans penis (primary syphilis) Condylomata lata of the glans penis (secondary syphilis) Condylomata lata in secondary syphilis Herpes genitalis Tzanck cell Chancroid lesion on the penis Inguinal lymphadenopathy in chancroid Trichomonas vaginalis

References

2015 Sexually Transmitted Diseases Treatment Guidelines: Gonococcal Infections. https://www.cdc.gov/std/tg2015/gonorrhea.htm. Updated: July 27, 2016. Accessed: March 25, 2017.
Guidance on the Use of Expedited Partner Therapy in the Treatment of Gonorrhea. https://www.cdc.gov/std/ept/gc-guidance.htm. Updated: March 1, 2021. Accessed: March 9, 2021.