Background Men-who-have-sex-with-men (MSM) are at increased risk for infection with enteric pathogens such as Shigella through sexual transmission. The etiology of acute gastroenteritis in this population has not been examined since the advent of molecular diagnostics. This study describes the causes of acute gastroenteritis in MSM in Seattle, Washington.

Methods Clinical and laboratory data were obtained for 226 MSM individuals seen in University of Washington-affiliated hospitals and clinics who underwent multiplex stool PCR testing (FilmArray GI Panel, BioFire Diagnostics, Salt Lake City, UT) from January 1, 2017 to June 1, 2018. Student’s t-test and chi-square were used to determine significant differences between HIV-positive and HIV-negative men.

Results Of 226 individuals tested, 130 (57.5%) had at least one positive stool test. Of individuals with a positive test result, 70% were HIV-positive. Sixty-one percent of HIV-negative patients were using PrEP. Of the positive samples, 88.7% detected a bacterial etiology, 26% detected a virus, and 40% a protozoal pathogen. Shigella, Campylobacter and diarrheagenic E. coli were the most commonly-detected bacteria (30.5%, 17.2% and 33.1% of positive samples, respectively), while norovirus was the most commonly-detected virus (15.2%), and Giardia was the most common parasite (20.5%). The etiologies of gastroenteritis were similar between HIV-positive and HIV-negative men. Cultured Shigella and Campylobacter isolates were frequently resistant to multiple antibiotics.

Conclusion MSM present with acute gastroenteritis caused by a range of pathogens, including some not detected by conventional stool culture, as well as sexually-transmitted pathogens such as Shigella, Campylobacter and Giardia. PrEP may be a risk factor for sexually-transmitted enteric infections as well as other STIs due to risk compensation. High levels of resistance to antibiotics used to treat gastroenteritis is consistent with a high rate of antibiotic exposure in this population and/or transmission of multi-resistant strains. New approaches may be needed to detect, treat and prevent enteric infections in MSM.

Disclosure No significant relationships.