Abstract and Introduction
Shigella spp. cause ≈500,000 illnesses in the United States annually, and resistance to ciprofloxacin, ceftriaxone, and azithromycin is emerging. We investigated associations between transmission route and antimicrobial resistance among US shigellosis clusters reported during 2011–2015. Of 32 clusters, 9 were caused by shigellae resistant to ciprofloxacin (3 clusters), ceftriaxone (2 clusters), or azithromycin (7 clusters); 3 clusters were resistant to >1 of these drugs. We observed resistance to any of these drugs in all 7 clusters among men who have sex with men (MSM) but in only 2 of the other 25 clusters (p<0.001). Azithromycin resistance was more common among MSM-associated clusters than other clusters (86% vs. 4% of clusters; p<0.001). For adults with suspected shigellosis, clinicians should culture feces; obtain sex histories; discuss shigellosis prevention; and choose treatment, when needed, according to antimicrobial drug susceptibility. Public health interviews for enteric illnesses should encompass sex practices; health messaging for MSM must include shigellosis prevention.
Shigellosis, the third most common human bacterial enteric infection in the United States, causes ≈500,000 illnesses each year. Because as few as 10 bacteria can cause infection, shigellosis outbreaks typically are large; control can be difficult unless interventions are implemented early in an outbreak. Although bloodstream infection is uncommon among immunocompetent hosts, shigellosis patients frequently are treated with antimicrobial medications to reduce illness duration and possibly transmission. High rates of resistance to ampicillin and trimethoprim/sulfamethoxazole have made ciprofloxacin, ceftriaxone, and azithromycin the preferred antimicrobial agents for adults and children with shigellosis; ceftriaxone is also the preferred treatment for invasive shigellosis.[4–6] However, shigellae resistant to these drugs have emerged in the United States and abroad.[7–17] Although shigellosis rates are highest for young children, most reports document ciprofloxacin- or azithromycin-resistant shigellosis largely among men who have sex with men (MSM).[7,8,10,12–17] Estimates of risk for antimicrobial drug–resistant shigellae among different populations or by transmission route have not been reported. We investigated the associations between transmission route and antimicrobial resistance among US shigellosis clusters reported during 2011–2015.
Emerging Infectious Diseases. 2016;22(9):1613-1616. © 2016 Centers for Disease Control and Prevention (CDC)