Drug-resistant bug concerns doctors

International travelers are returning to the U.S. with potentially deadly cargo: a multidrug-resistant form of the stomach bug shigella that defies a long list of antibiotics, including the first-choice drug Cipro.

Most forms of shigella have some degree of antibiotic resistance and the newly discovered form is the worst, experts said.

The Centers for Disease Control and Prevention found cases turning up individually and in clusters.

Dr. Aaron Glatt, a specialist in infectious diseases and a spokesman for the Infectious Diseases Society of America, said shigella causes a relatively common diarrheal disease called shigellosis.

Shigella is a fecal bacterium, Glatt said, and shigellosis can occur following ingestion of food or water contaminated with the bacteria.

“You see it frequently in army barracks, day care centers and other places where people are in close contact,” said Glatt, adding that most people are free of infection within a few days of following a course of antibiotics.

“But I am very concerned,” Glatt said, “when I hear that shigella is resistant to Cipro.”

The CDC has identified 243 infections. Clusters have emerged in Massachusetts, Pennsylvania and California. Individuals have been affected in 32 states and Puerto Rico.

CDC Director Thomas Frieden said multidrug-resistant shigella first emerged in India and the Dominican Republic.