Information for Healthcare Professionals
CDC Health Advisory: Increase in extensively drug-resistant Shigella infections (shigellosis) in the United States.
Antimicrobial-resistant Shigella infections in the United States
An estimated 242,000 antimicrobial-resistant Shigella infections occur in the United States each year. Antimicrobial-resistant Shigella infections are considered a serious threat for the following reasons:
- Multidrug resistance to trimethoprim-sulfamethoxazole, ciprofloxacin, and azithromycin is widespread in the U.S. and in other parts of the world, including Asia and parts of Africa.
- Since 2017, CDC’s National Antimicrobial Resistance Monitoring System (NARMS) has detected an increasing percentage of Shigella isolates that are resistant to both azithromycin and ciprofloxacin.
- Outbreaks of antimicrobial-resistant Shigella infections have been reported in the United States and other countries.
Diagnosis and Treatment
Testing the stool of patients with shigellosis-like symptoms is recommended. Characterizing isolates can lead to more accurate diagnoses, targeted treatment (when needed), improved patient outcomes, and earlier detection of outbreaks.
- When shigellosis is suspected, request a stool specimen for testing by culture or by a culture-independent diagnostic test (CIDT).
- If a CIDT is positive for shigellosis, confirm the diagnosis with a stool culture.
- Given the increasing rate of antimicrobial-resistant shigellosis, perform antimicrobial susceptibility testing if you plan to treat with an antibiotic.
- Shigellosis can be a mild, self-limited illness. When treatment is indicated, select an antimicrobial agent based on the susceptibility profile of the individual isolate or, during a local outbreak, on that of the outbreak strain. If antibiotics are needed before susceptibility results are available, select treatment based on local resistance data when available.
- Fluoroquinolones (such as ciprofloxacin), azithromycin, and third-generation cephalosporins (such as ceftriaxone) are recommended antibiotics. Trimethoprim-sulfamethoxazole and ampicillin are options if susceptibility is documented.
- If a patient has prolonged diarrhea (diarrhea lasting more than 3 days), follow-up stool cultures may be needed
Counseling patients with drug-resistant Shigella infections
Shigella is highly contagious; a very small inoculum (10 to 200 organisms) is sufficient to cause infection. To prevent the spread of Shigella bacteria, please share these prevention messages with your patients with shigellosis:
- Wash hands with soap and water for at least 20 seconds:
- After using the toilet
- After hanging a diaper or assisting anyone with toileting
- Note: Wash child’s hands in addition to your own.
- Avoid preparing food for friends, neighbors, colleagues, and (if possible) your family while you are sick.
- Try to stay home while you are sick.
- If you work in healthcare, childcare, or the food service industry, follow the guidance of your local health department about when it is safe to return to work.
- Children with shigellosis should not attend childcare, school, or group activities while they have diarrhea. Follow the guidance of your local health department about when it is safe to return to childcare or school.
- Avoid swimming until you have fully recovered.
- Wait to have sex (vaginal, anal, and oral) for one week after you no longer have diarrhea. Because Shigella germs may be in stool for several weeks, follow safe sex practices, or ideally avoid having sex, for several weeks after you or your partner have recovered.
- When you start having sex again, wash your body and hands before and after sex, including in and around the anus and genitals.
- During oral sex (fellatio or cunnilingus) or oral-anal sex (anilingus or mouth to anus), use barriers, such as condoms, natural rubber latex sheets, dental dams, or cut-open non-lubricated condoms between your rectum and your partner’s mouth.
- Use condoms the right way, every time during anal or vaginal sex. Wash hands after handling used condoms or other barriers.
- Urge others you know with similar symptoms to seek health care.
Watery, bloody, or prolonged diarrhea, abdominal pain, tenesmus, fever, and malaise. Stools tend to be of small volume, and severe dehydration is rare.
CDC estimates about 450,000 cases of shigellosis occur in the United States every year, making it the third most common bacterial enteric disease. Shigellosis does not have a marked seasonality, likely reflecting the importance of person-to-person transmission. For more information, see the FoodNet Annual Report.
In 2019, the incidence of shigellosis in the United States reported to the National Notifiable Diseases Surveillance System was 5.7 cases per 100,000 individuals.
Possible complications from Shigella infections include:
- Post-infectious arthritis. A syndrome of joint pain, eye irritation, and painful urination after an infection is called post-infectious arthritis. This can happen in about 2% of people who are infected with Shigella flexneri. Few cases have been reported in association with S. sonnei or S. dysenteriae infection. It can last for months or years, and can lead to chronic arthritis. Post-infectious arthritis is caused by a reaction to Shigella infection that happens only in people who are genetically predisposed to it.
- Bloodstream infections. Although rare, bloodstream infections are caused either by Shigella organisms or by other germs in the gut that get into the bloodstream when the lining of the intestines is damaged during shigellosis. Bloodstream infections are most common among patients with weakened immune systems, such as those with HIV, cancer, or severe malnutrition.
- Seizures. Generalized seizures have been reported occasionally among young children with shigellosis, and usually resolve without treatment. Children who experience seizures while infected with Shigella typically have a high fever or abnormal blood electrolytes, but it is not well understood why the seizures occur.
- Hemolytic-uremic syndrome or HUS. HUS occurs when bacteria enter the digestive system and produce a toxin that destroys red blood cells. Patients with HUS often have bloody diarrhea. When due to infection with Shigella, HUS is only associated with Shiga-toxin producing strains, most commonly Shigella dystenteriae.
Shigella germs are present in the stools of infected people while they have diarrhea and for up to a few weeks after the diarrhea has gone away. Transmission of Shigella occurs when people put something in their mouths or swallow something that has come into contact with stool of someone infected with Shigella. This can happen when:
- Contaminated hands touch someone’s food or mouth. Hands can become contaminated through a variety of activities, such as touching surfaces (e.g., toys, bathroom fixtures, changing tables, diaper pails) that have been contaminated by stool from an infected person. Hands also can become contaminated with Shigella bacteria while changing the diaper of an infected child or caring for an infected person.
- Eating food contaminated with Shigella bacteria. Food may become contaminated if food handlers have shigellosis. Produce can become contaminated if growing fields contain human sewage. Flies can breed in infected feces and then contaminate food when they land on it.
- Swallowing recreational water (for example, lake or river water) while swimming, or drinking water that has been contaminated by fecal matter containing Shigella.
- Exposure to feces through sexual contact.
People at Risk
- Young children are the most likely to get shigellosis, but people of all ages are affected. Many outbreaks are related to childcare settings and schools, and illness commonly spreads from young children to their family members and others in their communities because it is so contagious.
- Gay and bisexual men and other men who have sex with men (MSM)* are among the groups at high risk for Shigella infection. In recent years, multiple outbreaks of antimicrobial-resistant Shigella infections among gay, bisexual, and other men who have sex with men have been reported worldwide. For more information, see Shigella Infections Among Gay & Bisexual Men.
- People with HIV and those who are immunocompromised can have more severe and prolonged shigellosis, including having the infection spread into the blood, which can be life-threatening.
- Travelers to places where water and food may be unsafe and sanitation is poor are more likely to get a Shigella infection. They are also more likely to become sick with types of Shigella that are more difficult to treat. Shigella can spread to travelers through contaminated food, water (both drinking and recreational water), surfaces, or from other people. Travelers can protect themselves by strictly following food and water precautions and washing hands with soap frequently.
* The term “men who have sex with men” is used in CDC surveillance systems because it indicates men who engage in behaviors that may transmit Shigella infection, rather than how someone identifies their sexuality.