UC San Diego

Annually, Shigella spp. cause ≈188 million cases of diarrheal disease globally, including 500,000 cases in the United States; rates of antimicrobial resistance are increasing. To determine antimicrobial resistance and risk factors in San Diego, California, USA, we retrospectively reviewed cases of diarrheal disease caused by Shigella flexneri and S. sonnei diagnosed during 2017-2020. Of 128 evaluable cases, S. flexneri was slightly more common than S. sonnei; most cases were in persons who were gay or bisexual cisgender men, were living with HIV, were unhoused, or used methamphetamines. Overall, rates of resistance to azithromycin, fluoroquinolones, ampicillin, and trimethoprim/sulfamethoxazole (TMP/SMX) were comparable to the most recent national data reported from the Centers for Disease Control and Prevention; 55% of isolates were resistant to azithromycin, 23% to fluoroquinolones, 70% to ampicillin, and 83% to TMP/SMX. The rates that we found for TMP/SMX were slightly higher than those in national data.