Sexually transmitted infections

Last updated: July 1, 2022

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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


Associated disease Management
Viral pathogens
Human papillomavirus type 6 and 11

Herpes simplex virus type 2 (HSV-2)

  • Acyclovir PO for episodic or suppressive treatment
Hepatitis B virus (HBV)
  • Systemic antiviral therapy PO (e.g., entecavir)
  • Interferon (immune-modulating, antiviral, and antiproliferative agent) injected SC or IM
Bacterial pathogens
Chlamydia trachomatis D–K
Chlamydia trachomatis L1–L3
Klebsiella granulomatis
Haemophilus ducreyi
Neisseria gonorrhea
Treponema pallidum
Parasitic pathogens
Trichomonas vaginalis
Phthirus pubis
Overview of genital lesions
Pathogen Clinical features Diagnosis
Painless lesions
Human papillomavirus type 6 and 11
Klebsiella granulomatis
Chlamydia trachomatis L1–L3
Treponema pallidum
Painful lesions
Herpes simplex virus type 1 and 2 (mostly HSV-2)
Haemophilus ducreyi
  • Clinical exam and culture

Trichomonas vaginalis

  1. 2015 Sexually Transmitted Diseases Treatment Guidelines: Gonococcal Infections. Updated: July 27, 2016. Accessed: March 25, 2017.
  2. Guidance on the Use of Expedited Partner Therapy in the Treatment of Gonorrhea. Updated: March 1, 2021. Accessed: March 9, 2021.
  3. Molina J-M, Charreau I, Chidiac C, et al. Post-exposure prophylaxis with doxycycline to prevent sexually transmitted infections in men who have sex with men: an open-label randomised substudy of the ANRS IPERGAY trial. Lancet Infect Dis. 2018; 18 (3): p.308-317. doi: 10.1016/s1473-3099(17)30725-9 . | Open in Read by QxMD

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