Multidrug-Resistant Shigellosis Spreads Throughout the United States

International travelers are bringing a multidrug-resistant intestinal illness called shigellosis to the USA and spreading it to others who have not traveled.

Shigella sonnei, the causative bacteria of the disease, have become resistant to the antibiotic ciprofloxacin which is the first choice to treat shigellosis among adults in the USA. Shigellosis can spread very quickly in groups like children in childcare facilities, homeless people, and gay and bisexual men, as occurred in several outbreaks.


Scientists at the Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) identified an increase in Shigella sonnei infections with an uncommon genetic fingerprint in December 2014. Further testing at CDC's National Antimicrobial Resistance Monitoring System (NARMS) laboratory found that the bacteria were resistant to ciprofloxacin (Cipro). The CDC’s PulseNet network detected several large clusters: 45 cases in Massachusetts; 25 cases in California; and 18 cases in Pennsylvania. About half of these cases with patient information were associated with international travel, mostly to the Dominican Republic and India. The San Francisco Department of Public Health (CA, USA) reported another 95 cases, with 9 of them among those identified by PulseNet, with almost half occurring among the homeless or people living in single-room occupancy hotels.

Shigella causes an estimated 500,000 cases of diarrhea in the USA every year. It spreads easily and rapidly from person to person and through contaminated food and recreational water. It can cause watery or bloody diarrhea, abdominal pain, fever, and malaise. Although diarrhea caused by Shigella typically goes away without treatment, people with mild illnesses are often treated with antibiotics to stop the diarrhea faster.

Until recently, Cipro resistance has occurred in just 2% of Shigella infections tested in the USA, but was found in 90% of samples tested in the recent clusters. The CDC recommends that health care providers should test stool samples from patients with symptoms consistent with shigellosis, re-test stool if patients do not improve after taking antibiotics, and test bacteria for antibiotic resistance.

Anna Bowen, MD, MPH, a medical officer at the CDC and lead author of the study said, “Shigella is already resistant to the antibiotics ampicillin and trimethoprim/sulfamethoxazole. Globally, Shigella resistance to Cipro is increasing. The increase in drug-resistant Shigella makes it even more critical to prevent shigellosis from spreading. Washing your hands with soap and water is important for everyone. Also, international travelers can protect themselves by choosing hot foods and drinking only from sealed containers.”

Related Links:
Centers for Disease Control and Prevention 
San Francisco Department of Public Health