The Centers for Disease Control and Prevention is warning clinicians and public health departments about a sharp rise in serious gastrointestinal infections caused by bacteria that are resistant to common antibiotics.
In a health advisory issued Friday, the CDC said the agency has been monitoring an increase in people infected with strains of Shigella bacteria that are highly resistant to available drugs. Shigella infections, known as shigellosis, usually cause diarrhea that can be prolonged and bloody, as well as fever and abdominal cramps.
In the past, shigellosis has predominantly affected children under 4. But CDC said it has seen a recent increase in drug-resistant infections in adults, especially men who have sex with men, international travelers, people living with HIV and people experiencing homelessness.
Most people recover without treatment with antibiotics. But people who have weakened immune systems, including those with HIV or who are receiving chemotherapy, can get a more serious illness. Severe shigellosis can spread into the blood, which can be life-threatening.
Drug-resistant Shigella infections "are challenging to treat and easily transmissible, especially among vulnerable populations," said Naeemah Logan, a CDC medical officer, in an email. These "superbug" infections "are a serious public health threat, and we want to ensure that providers are aware of the increasing potential for antibiotics to fail."
The agency has scheduled a call next week to brief clinicians about the rise in cases and how to manage them.
Shigella cause an estimated 450,000 infections in the United States each year. In 2022, about 5 percent of Shigella infections reported to the CDC were caused by super-resistant strains, compared with none in 2015.
Of 237 patients with resistant infections that were reported during this period, more than 90 percent of them happened during the pandemic, between 2020 and 2022, according to the CDC. Resistant infections have been reported in 29 states, with the largest numbers in California (76), Colorado (36) and Massachusetts (34), according to CDC data.
These strains are resistant to five commonly recommended antibiotics, including azithromycin, ciprofloxacin and ceftriaxone.
Last year, the CDC said the pandemic caused a surge in overall superbug infections and deaths in U.S. hospitals, reversing years of progress. Public health efforts had driven down resistant infections in hospitals by nearly 30 percent between 2012 and 2017. But in 2020, the pandemic pushed hospitals, health departments and communities to near breaking points.
Sicker patients needed more frequent and longer use of medical devices, such as catheters and ventilators, that break the body's natural protective barrier - the skin - and so increase infection risk. In addition, clinicians unfamiliar with the coronavirus at first relied heavily on antibiotics to treat patients. But those lifesaving drugs work against bacteria, not against viruses.
The unusually high levels of antibiotic use probably allowed drug resistance to develop and spread.
Shigella bacteria spread rapidly and easily through direct person-to-person contact, including sexual contact. They also spread indirectly through contaminated food, water and other routes. It takes just a small number of bacteria to make someone sick, and infected people can spread the germs to others for several weeks after their diarrhea ends.
The CDC said it does not currently have recommendations for the best way to treat highly resistant Shigella infections.
In recent months, global cases of shigellosis have been on the rise. In January 2022, the United Kingdom reported an increase in cases of extremely antibiotic-resistant infections, mainly in men who have sex with men.
As of mid-February, a dozen countries, including the United States, have reported more than 250 Shigella infections since September 2022 in people who went to Cape Verde in West Africa, according to the European Centre for Disease Control and Prevention.
Shigellosis symptoms usually start one to two days after infection and last seven days. In some cases, bowel habits don’t return to normal for several months.