Enteric Fever and Antimicrobial Resistance

Importance: Increasing antibiotic resistance in enteric fever (typhoid or paratyphoid fever) is a global public health threat. Knowledge of current antimicrobial resistance patterns and identification of factors associated with acquiring resistant infections can help inform treatment and prevention decisions.

Objective

To estimate the prevalence of antimicrobial-resistant enteric fever in the US after the emergence of extensively drug-resistant Salmonella enterica Typhi in 2016 and describe characteristics of patients with resistant Salmonella Typhi or Paratyphi strains. Design, setting, and participants: This cross-sectional, laboratory-based study included cases of culture-confirmed enteric fever diagnosed in the US. From January 2016 to December 2020, US health departments submitted epidemiologic data to the Centers for Disease Control and Prevention (CDC) through the National Typhoid and Paratyphoid Fever Surveillance (NTPFS) system, and public health laboratories submitted the corresponding Typhi or Paratyphi isolates to the CDC through the National Antimicrobial Resistance Monitoring System (NARMS). Initial data analysis was complete by March 31, 2023, and the antimicrobial resistance trends analysis was updated in August 2026. Exposures: Patient variables collected by the NTPFS, including demographic characteristics, travel history, and typhoid vaccination status. Main outcome and measures: Linked NTPFS-NARMS data from 2016 to 2020 were used to calculate the prevalence of antimicrobial resistance stratified by serotype and to conduct univariable logistic regression to estimate the associations of case characteristics and exposure variables with odds of infection with resistant strains.