In the past, shigellosis has mainly affected children under 4 years of age. 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 those who are homeless.
Most people recover without antibiotic treatment. But people with weakened immune systems, including those with HIV or who are receiving chemotherapy, can develop 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,” Naeemah Logan, a CDC physician, said in an email. These “superbug” infections “are a serious threat to public health, and we want to make sure providers are aware of the increasing likelihood of antibiotic failure.”
The agency has scheduled a call next week to inform clinicians about the increase in cases and how to manage them.
Shigella causing 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 superdrug-resistant strains, compared to none in 2015.
Of the 237 patients with drug-resistant infections reported during this period, that was over 90 percent happened during the pandemic, between 2020 and 2022, according to the CDC. Drug-resistant infections have been reported in 29 states, with the highest 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 sparked a wave of all-out superbug infections and deaths in U.S. hospitals, undoing years of progress. Public health efforts had reduced the number of drug-resistant infections in hospitals by nearly 30 percent between 2012 and 2017. But in 2020, the pandemic drove hospitals, health departments and communities to near breaking points.
Sick patients required more frequent and longer medical devices, such as catheters and ventilators, that break through the body’s natural protective barrier – the skin – thus increasing the risk of infection. In addition, clinicians unfamiliar with the coronavirus initially relied heavily on antibiotics to treat patients. But those life-saving drugs work against bacteria, not viruses.
It unusual high levels of antibiotic use likely allowed drug resistance to develop and spread.
Shigella bacteria spread quickly and easily through direct personal contact, including sexual contact. They also spread indirectly through contaminated food, water and other routes. It only takes a small number of bacteria to make someone sick, and infected people can still spread the germs to others for several weeks after their diarrhea ends.
The CDC said it currently has no recommendations for the best way to treat highly resistant Shigella infections.
In recent months, there have been an increasing number of cases of shigellosis worldwide. In January 2022, the United Kingdom reported an increase in cases of extremely antibiotic-resistant infections, particularly among 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 Center for Disease Control and Prevention.
Symptoms of shigellosis usually begin one to two days after infection and last seven days. In some cases, bowel movements do not return to normal for several months.