This clinical trial aims to investigate the effects of a decline in methamphetamine use on rectal inflammatory cytokine levels, substance use contexts, and HIV/STI risk behavior. This clinical trial also seeks to evaluate joint effects of methamphetamine use and rectal gonorrhea/chlamydia infection on rectal inflammatory cytokine levels. The proposed trial will consist of 40 MSM, half with rectal gonorrhea/chlamydia infection at enrollment (n=20), with methamphetamine use disorder that will receive contingency management for methamphetamine reduction. Following baseline measurement, participants will be observed over the course of 8 weeks, where participants will complete behavioral surveys, provide urine for drug testing, and rectal samples for measurement of rectal inflammatory cytokine levels.

Inclusion Criteria:

• Cisgender male
• 18 years of age or older
• Understand written and spoken English
• Condomless receptive anal intercourse in past 90 days
• Meet DSM-5 criteria for methamphetamine use disorder
• Positive urine toxicology screen for MA metabolites at study entry
• Negative rectal GC/CT screen (n=20) or Positive rectal GC and/or CT screen (n=20)
• Able to provide written informed consent and willing/able to complete study visits.

Exclusion Criteria:

• Reports current treatment for another substance use disorder
• Positive test for opioids, cocaine, and/or hallucinogens
• Treatment for gonorrhea and/or chlamydia infection in past 3 months
• Presence of a condition that in the opinion of the investigator would compromise the safety of the patient or the quality of the data

Participants who were lost to follow-up were not included in analyses

From enrollment until end of follow-up, up to 8 weeks