Shigella cause an estimated 450,000 infections in the United States each year and an estimated $93 million in direct medical costs.
The CDC is reporting an increase in drug-resistant Shigella infections (shigellosis). Around 5% of Shigella infections reported to CDC were caused by drug-resistant strains, compared with 0 in 2015, CDC said in a Health Advisory. Shigella bacteria are easily transmissible, and clinicians treating patients infected with drug-resistant strains have limited antimicrobial treatment options, the agency noted. Shigella infections cause an estimated 450,000 infections in the United States each year and an estimated $93 million in direct medical costs, according to the CDC.
Shigellosis is an acute enteric infection that is an important cause of domestically acquired and travel-associated bacterial diarrhea in the United States. It usually causes inflammatory diarrhea that can be bloody and may also lead to fever, and abdominal cramping.
Shigella bacteria are resistant to all commonly recommended empiric and alternative antibiotics — azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole (TMP-SMX), and ampicillin, CDC noted. “Currently, there are no data from clinical studies of treatment of drug-resistant Shigella to inform recommendations for the optimal antimicrobial treatment of these infections. As such, CDC does not have recommendations for optimal antimicrobial treatment of drug-resistant Shigella infections,” the agency said.
Most shigella infections resolve on their own. While antibiotics such as azithromycin and ciprofloxacin are often used to treat patients with severe infection or weakened immune systems.
Shigella infections can be shortened by oral antibiotics but are not necessary for treatment, Bayli Larson, Pharm.D., MS, BCPS, strategic initiatives associate at the American Society of Health-Systems Pharmacists, told Formulary Watch.
Importantly, there is little overlap between recommended antibiotics and those on ASHP’s Drug Shortages Database list, Larson said. “Recommended first-line oral antibiotics azithromycin and ciprofloxacin are not currently on shortage, as well as those that might be used to treat resistant Shigella infections, including ceftriaxone and ofloxacin.”
Related: Hospital Demand for Amoxicillin Increases While Shortage Continues
It is not uncommon for some bacterial infections to be resistant to certain antibiotics, which may present challenges for prescribing second-line therapies, Larson said. “This is why it’s critical that pharmacists work closely with other members of the healthcare team and have protocols in place via antibiotic stewardship committees,” she noted. “Ensuring that the appropriate antibiotic and/or antiviral is used safely, and effectively is crucial for public health.”
Drug-resistant Shigella strains, however, can spread antimicrobial resistance genes to other enteric bacteria, the CDC noted. “Given these potentially serious public health concerns, CDC asks healthcare professionals to be vigilant about suspecting and reporting cases of drug-resistant Shigella infection to their local or state health department and educating patients and communities at increased risk about prevention and transmission,” the agency said.
Shigella bacteria are transmitted by the fecal-oral route, directly through person-to-person contact including sexual contact, and indirectly through contaminated food, water, and other routes. Shigella bacteria are easily transmitted because of the low infectious dose (as few as 10–100 organisms), and outbreaks tend to occur among people in close-contact settings, according to the CDC.
While shigellosis has predominantly affected young children (age 1–4 years), the CDC has recently observed an increase in antimicrobial-resistant Shigella infections among adult populations, especially gay, bisexual, and other men who have sex with men, people experiencing homelessness, international travel, and people with HIV.