What are the common sexually transmitted infections (STIs) in men who have sex with men?

Common Sexually Transmitted Infections in Men Who Have Sex with Men

Men who have sex with men (MSM) have significantly higher rates of sexually transmitted infections (STIs) compared to the general population, with several specific infections being particularly prevalent in this population.

Key STIs in MSM

Bacterial Infections

• Gonorrhea is one of the most common STIs among MSM, with prevalence rates of up to 16% reported in STD clinic settings 1. Rectal gonorrhea is particularly common, with 51.4% of gonorrhea infections in MSM occurring at the rectal site 2.

• Chlamydia is highly prevalent among MSM with rates of approximately 12% in STD clinic settings 1. Similar to gonorrhea, rectal chlamydia is particularly common, with 69.1% of chlamydia infections in MSM occurring at the rectal site 2.

• Syphilis disproportionately affects MSM, with studies documenting an 18% prevalence of HIV co-infection among patients with early syphilis in several large US cities 1. Syphilis outbreaks continue to occur in MSM communities despite declining rates in the general population 1.

Viral Infections

• HIV remains a significant concern, with MSM accounting for a substantial proportion of new HIV infections. The presence of other STIs increases the risk of HIV acquisition and transmission 1.

• Hepatitis (particularly hepatitis B) occurs at higher rates in MSM compared to the general population 3.

• Human Papillomavirus (HPV) infections are common among MSM, leading to increased risk of anal dysplasia and cancer 3.

• Herpes Simplex Virus type 2 (HSV-2) is prevalent among MSM and can facilitate HIV transmission 1.

Epidemiology and Risk Factors

• The incidence of bacterial STIs among MSM at high risk for HIV has been estimated at 9.1/100 person-years for syphilis, 39.6/100 person-years for gonorrhea, and 41.8/100 person-years for chlamydia 4.

• Asymptomatic infections are common, with studies showing a baseline prevalence of 14% and an incidence of 20.8 cases per 100 person-years for asymptomatic STIs among HIV-infected MSM 5.

• Risk factors associated with increased STI acquisition include:

  • Younger age (particularly 18-24 years) 2
  • Multiple sexual partners 6
  • Substance use, particularly marijuana 5
  • HIV infection or use of HIV pre-exposure prophylaxis (PrEP) 2
  • Being from racial/ethnic minority groups 2

Anatomical Sites of Infection

• Multi-site infections are common in MSM due to diverse sexual practices 3:
  • Rectal infections: Particularly common for gonorrhea (51.4%) and chlamydia (69.1%) 2
  • Pharyngeal infections: Often asymptomatic but serve as reservoirs for transmission 3
  • Urogenital infections: Less common than rectal infections but still significant (31% for gonorrhea, 34.3% for chlamydia) 2

Screening Recommendations

• The CDC recommends annual screening for all sexually active MSM and more frequent screening (every 3-6 months) for MSM with multiple or anonymous partners, those who use drugs during sex, or have partners who engage in these activities 1.

• Comprehensive screening should include:

  • Testing for gonorrhea and chlamydia at all potential exposure sites (pharynx, rectum, urethra) 1
  • Serologic testing for syphilis 1
  • HIV testing 1
  • Hepatitis screening and vaccination when appropriate 3

• Doxycycline post-exposure prophylaxis (doxy PEP) is now recommended by the CDC for MSM and transgender women who have had a bacterial STI diagnosed in the past 12 months. The recommended dose is 200 mg taken within 72 hours after sex 1.

Clinical Implications

• High rates of asymptomatic infections necessitate regular screening even in the absence of symptoms 5.

• Co-infections are common, particularly HIV and syphilis, requiring comprehensive testing 1.

• Antimicrobial resistance, particularly in gonorrhea, is a growing concern requiring appropriate treatment and follow-up 7.

• Increased screening frequency (biannual rather than annual) for all sexually active MSM could avert up to 72% of gonorrhea and 78% of chlamydia infections over 10 years 6.

Prevention Strategies

• Regular screening is essential for early detection and treatment of STIs 5.

• Risk reduction counseling should be provided to all MSM diagnosed with STIs 1.

• Partner notification and treatment are crucial to prevent reinfection 1.

• Vaccination against preventable STIs such as hepatitis A and B and HPV should be offered 3.

• PrEP users should receive comprehensive STI screening as they may have higher rates of bacterial STIs 2.