Centers for Disease Control and Prevention

Antimicrobial Resistance Threats Report

Drug-resistantSalmonella Typhi

Threat Level: SERIOUS

In the United States in 2023:

CDC changed methodologies and data sources to produce the most comprehensive AR Threats Report to date. Direct comparison of this threat's data to previous reports is not recommended.

What you need to know

Salmonella Typhi bacteria cause typhoid fever, a life-threatening disease. Salmonella Typhi spread commonly through contaminated food, water, and other drinks; through food washed with contaminated water; and through contact with someone who is sick or was recently sick with typhoid fever. Most people become infected during travel to countries with poor sanitation and contaminated food and water. Getting a typhoid vaccine before traveling and practicing safe eating and drinking habits during travel can help prevent infections.

People with symptoms—such as a high fever lasting more than three days, stomach pain, and headache—should get medical help immediately. Without treatment, the fever can last weeks or months and lead to serious health problems. Typhoid fever is treated with antibiotics, but increasing drug resistance can limit treatment options. Healthcare providers should order laboratory tests to determine which antibiotics might be effective.

Drug-resistant Salmonella Typhi data

Drug-resistant Salmonella Typhi infections remain a public health concern because resistance to key treatment options, including ciprofloxacin and ceftriaxone, has increased over time. As resistance increases, ongoing surveillance is essential to monitor trends and help inform prevention and treatment strategies.

Estimated number of drug-resistant Salmonella Typhi infections and hospitalizations by year in the U.S.

Drug-resistant Salmonella Typhi caused an estimated 5,200 infections in 2022 and 7,100 infections in 2023. These bacteria caused an estimated 700 hospitalizations in 2022 and 860 hospitalizations in 2023.

The percentage of Salmonella Typhi isolates (pure samples of Salmonella Typhi) that are resistant to key treatment options has increased over time.

Percent resistant or nonsusceptible to antibiotics by year among Salmonella Typhi isolates tested in the U.S.

The percentage of Salmonella Typhi isolates nonsusceptible (resistant or not completely susceptible) to ciprofloxacin has increased since 2011 and was 85.9% in 2023. Resistance to ceftriaxone began increasing in 2018 and was 8.2% in 2023. Multidrug resistance (MDR), defined as resistance to at least ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole, and nonsusceptible to ciprofloxacin, has remained generally stable since 2011 and was 10.9% in 2023. The percentage of extensively drug-resistant (XDR) isolates, defined as MDR and resistant to ceftriaxone, also began increasing in 2018 and was 5.6% in 2023.

Effective treatment of typhoid fever depends on antibiotics to shorten illness, reduce the risk of severe complications, and prevent death. As resistance to commonly used antibiotics increases, the antibiotics given before susceptibility results are available are less likely to be effective. Salmonella Typhi infections become more difficult to treat as treatment options become more limited. Surveillance helps detect emerging resistance patterns so healthcare providers and public health officials can monitor changes over time and make informed decisions about treatment and prevention.

Concerning illness after travel

A traveler in an airport terminal watches a plane take off.

Getting a typhoid vaccine before travel to places where typhoid fever is common can help prevent infections, limit the spread of drug-resistant Salmonella Typhi, and reduce the need for antibiotics.

After traveling to New Delhi, India, to visit family and attend a large wedding, a mother and her adult daughter returned home to the United States. Although they never felt sick during their trip, an unwelcome guest came home with them: extensively drug-resistant (XDR) Salmonella Typhi. XDR Salmonella Typhi are resistant to most antibiotics typically used for treatment in the United States, limiting treatment options.
After the mother and daughter started to feel sick, they ended up in the hospital. There they were diagnosed with typhoid fever and given multiple antibiotics before starting to recover. Testing revealed that they had the first U.S. cases of typhoid fever that were both XDR and had azithromycin resistance.
Healthcare providers have fewer options to treat typhoid fever than in the past. For XDR Salmonella Typhi, azithromycin is often the only effective treatment that patients can take by mouth. When azithromycin is not an option, patients may need to be hospitalized and receive a carbapenem, which is an antibiotic given intravenously (by IV) and typically used as a last resort for typhoid fever. Carbapenems can be costly for patients because they must be given by a healthcare provider and are generally more expensive than oral antibiotics.
The lack of alternative oral treatments for XDR typhoid fever highlights the importance of preventing infections from happening in the first place. Getting a vaccine before traveling to places where typhoid fever is common and practicing safe eating and drinking habits during travel can help prevent typhoid fever. During 2021 to 2023, 97% of U.S. patients who had typhoid fever were unvaccinated. Increasing awareness of the typhoid vaccine and access to it before international travel are key to preventing future infections, limiting the spread of drug-resistant Salmonella Typhi, and reducing the need for antibiotics.

How CDC combats drug-resistant Salmonella Typhi

  • Detecting new and emerging resistance

    CDC partners with state and local health departments to track emerging resistance among Salmonella Typhi. Data from whole genome sequencing and antimicrobial susceptibility testing help identify new and concerning strains and guide prevention strategies.

  • Tracking concerning strains

    CDC works with state and federal partners to identify, track, and investigate these strains. CDC shares this information to promote collaboration, stimulate research, and support typhoid fever prevention efforts.

  • Understanding sources of infections

    CDC works with health departments to collect detailed information from patients with Salmonella Typhi, including international travel history, possible exposures, and typhoid vaccination status. These data inform our understanding of typhoid fever in the United States and help guide efforts to prevent infections.

  • Preparing travelers

    CDC publishes travel notices and provides vaccination recommendations, tips for safe eating and drinking during international travel, and resources and guidance for all travel destinations. Informing travelers about typhoid fever risks can help them prevent infections and the spread of drug-resistant Salmonella Typhi.

  • Informing healthcare providers

    CDC provides information that clinicians can use to identify, diagnose, and treat typhoid fever and patients can use to understand ways to prevent infections. CDC also notifies healthcare professionals about concerning strains of Salmonella Typhi and provides treatment recommendations for patients with drug-resistant infections.

Drug-resistant Salmonella Typhi resources

Illustration of Drug-resistant Salmonella Typhi