Nearly half of MSM taking HIV PrEP tested positive for gastr
In a small study, researchers detected gastrointestinal pathogens in 45% of men who have sex with men taking HIV PrEP, according to findings published in Open Forum Infectious Diseases.

Researchers assessed the prevalence of GI pathogens and correlation with clinical factors among HIV-negative MSM receiving PrEP at a New York City sexual health clinic. According to the study, they collected an additional flocculated rectal swab concurrently with a rectal swab for gonorrhea and chlamydia testing at regular 3-month clinic visits for PrEP follow-up and tested them for 22 organisms.

110 of 148 participants in a PrEP adherence study called Stick2PrEP enrolled in the GI pathogen substudy, with a total of 194 rectal swabs collected.

According to the study, at least one organism was detected in 62 (32%) rectal swabs from 50 (45%) participants. Testing detected enteropathogenic Escherichia coli in 20 (10%) swabs, Giardia lamblia in 19 (10%), enteroaggregative E. coli in 16 (8%), Campylobacter in 14 (7%), Shigella/enteroinvasive E. coli in four (2%), enterotoxigenic E. coli in one, Vibrio in two, Cryptosporidium in two, Norovirus in two and Sapovirus in one.

In some study participants, pathogens were detected in multiple swabs, including two participants who had Giardia detected on three consecutive swabs, one who had Campylobacter detected on three consecutive swabs and another patient who had enteropathogenic E. coli detected on three consecutive swabs, researchers reported.

The study also demonstrated that the frequency of symptoms was high regardless of swab results, with 66% of positive and 62% of negative swabs being associated with one or more symptoms. The most commonly reported symptoms were diarrhea (43%), abdominal discomfort (32%), urgency (27%), tenesmus (18%), nausea (18%) and mucus in stool (10%).

“Overall, they found a high rate of enteric pathogen detection among HIV-negative MSM taking PrEP, with 45% of participants having at least one positive rectal swab during the study period,” the authors wrote. “Given these concerns, sexual health testing strategies should consider the use of multiplex PCR screening for GI pathogens in MSM with GI symptoms, and asymptomatic screening may be beneficial in high prevalence or outbreak settings.”