CDC: International travelers are bringing a multidrug-resistant intestinal illness to the United States and spreading it to others who have not traveled, according to a report released today by the Centers for Disease Control and Prevention (CDC). Shigella sonnei bacteria resistant to the antibiotic ciprofloxacin sickened 243 people in 32 states and Puerto Rico between May 2014 and February 2015. Research by the CDC found that the drug-resistant illness was being repeatedly introduced as ill travelers returned and was then infecting other people in a series of outbreaks around the country.
CDC and public
health partners investigated several recent clusters of shigellosis in
Massachusetts, California and Pennsylvania and found that nearly 90
percent of the cases tested were resistant to ciprofloxacin (Cipro), the
first choice to treat shigellosis among adults in the United States.
Shigellosis can spread very quickly in groups like children in childcare
facilities, homeless people and gay and bisexual men, as occurred in
“These outbreaks show a troubling trend in Shigella
infections in the United States,” said CDC Director Tom Frieden, M.D.,
M.P.H. “Drug-resistant infections are harder to treat and because Shigella
spreads so easily between people, the potential for more – and larger –
outbreaks is a real concern. We’re moving quickly to implement a
national strategy to curb antibiotic resistance because we can’t take
for granted that we’ll always have the drugs we need to fight common
In the United States, most Shigella is already resistant to the antibiotics ampicillin and trimethoprim/sulfamethoxazole. Globally, Shigella
resistance to Cipro is increasing. Cipro is often prescribed to people
who travel internationally, in case they develop diarrhea while out of
the United States. More study is needed to determine what role, if any,
the use of antibiotics during travel may have in increasing the risk of
antibiotic-resistant diarrhea infections among returned travelers.
“The increase in drug-resistant Shigella
makes it even more critical to prevent shigellosis from spreading,”
said Anna Bowen, M.D., M.P.H., a medical officer in CDC’s Waterborne
Diseases Prevention Branch and lead author of the study. “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.”
CDC’s PulseNet lab network 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) lab found that the bacteria were resistant to Cipro.
PulseNet detected several large clusters: 45 cases in Massachusetts; 25
cases in California; and 18 cases in Pennsylvania. About half of the
PulseNet cases with patient information were associated with
international travel, mostly to the Dominican Republic and India. The
San Francisco Department of Public Health reported another 95 cases
(nine of them among those identified by PulseNet), with almost half
occurring among the homeless or people living in single-room occupancy
Shigella causes an estimated 500,000 cases of
diarrhea in the United States 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 percent of Shigella infections tested in the United States, but was found in 90 percent of samples tested in the recent clusters.
Because Cipro-resistant Shigella
is spreading, CDC recommends doctors use lab tests to determine which
antibiotics will effectively treat shigellosis. Doctors and patients
should consider carefully whether an infection requires antibiotics at
To prevent the spread of shigellosis, CDC recommends that
people wash their hands often with soap and water, especially after
using the toilet and before preparing food or eating; keep children home
from childcare and other group activities while they are sick with
diarrhea; avoid preparing food for others while ill with diarrhea; and
avoid swimming for a few weeks after recovering. Improving access to
toilets and soap and water for washing hands may help prevent Shigella transmission among the homeless.
to developing countries can take additional precautions to avoid
diarrhea and minimize infection with resistant bacteria. Choose safe
foods and beverages, such as food that is steaming hot and drinks from
sealed containers (download CDC’s app “Can I Eat This?”
to help you make safer food and beverage choices when you travel).
Wash hands frequently, particularly before eating and after using the
toilet. Take bismuth subsalicylate to prevent travelers’ diarrhea and
treat it with over-the-counter drugs like bismuth subsalicylate or
loperamide. Try to reserve antibiotics for severe cases of travelers’
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
For more information on Shigella, please visit: www.cdc.gov/shigella.
Travelers can learn more about food and water precautions to prevent Shigella at: http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-2-the-pre-travel-consultation/food-and-water-precautions.