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. 2023 Aug 31;228(5):533-541.
doi: 10.1093/infdis/jiad128.

Antimicrobial-Resistant Nontyphoidal Salmonella Infection Following International Travel-United States, 2018-2019

Laura Ford  1   2 , Hazel J Shah  2 , Dana Eikmeier  3 , Samir Hanna  4 , Jessica Chen  2 , Kaitlin A Tagg  2   5 , Gayle Langley  2 , Daniel C Payne  2 , Ian D Plumb  2
Affiliations

Antimicrobial-Resistant Nontyphoidal Salmonella Infection Following International Travel-United States, 2018-2019

Laura Ford et al. J Infect Dis. .

Abstract

Background: Antimicrobial resistance in nontyphoidal Salmonella (NTS) can limit treatment options. We assessed the contribution of international travel to antimicrobial-resistant NTS infections.

Methods: We describe NTS infections that were reported to the Foodborne Diseases Active Surveillance Network during 2018-2019 and screened for genetic resistance determinants, including those conferring decreased susceptibility to first-line agents (ciprofloxacin, ceftriaxone, or azithromycin). We used multivariable logistic regression to assess the association between resistance and international travel during the 7 days before illness began. We estimated the contribution of international travel to resistance using population-attributable fractions, and we examined reported antimicrobial use.

Results: Among 9301 NTS infections, 1159 (12%) occurred after recent international travel. Predicted resistance to first-line antimicrobials was more likely following travel; the adjusted odds ratio varied by travel region and was highest after travel to Asia (adjusted odds ratio, 7.2 [95% confidence interval, 5.5-9.5]). Overall, 19% (95% confidence interval, 17%-22%) of predicted resistance to first-line antimicrobials was attributable to international travel. More travelers than nontravelers receiving ciprofloxacin or other fluoroquinolones had isolates with predicted resistance to fluoroquinolones (29% vs 9%, respectively; P < .01).

Conclusions: International travel is a substantial risk factor for antimicrobial-resistant NTS infections. Understanding risks of resistant infection could help target prevention efforts.

Keywords: drug resistance; foodborne disease; salmonella; travel.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Odds of resistance in nontyphoidal Salmonella infections in adults (A, B) and incidence rate per 100 000 adult travelers (C, D), by region of travel in the 7 days before illness began in 2018–2019. Note: Latin America includes the Caribbean and Mexico. Resistance to first-line antibiotics (“first-line resistance”) is defined as the presence of a resistance gene or mutation conferring decreased susceptibility to ciprofloxacin, ceftriaxone, or azithromycin; resistance to any antibiotics (“any resistance”), as the presence of a resistance gene or mutation conferring decreased susceptibility to amikacin, gentamicin, kanamycin, streptomycin, amoxicillin–clavulanic acid, cefoxitin, ceftriaxone, sulfisoxazole, trimethoprim-sulfamethoxazole, azithromycin, ampicillin, chloramphenicol, ciprofloxacin, or tetracycline. Odds ratios (ORs) were adjusted for age, sex, and season of infection, and adjusted ORs were not calculated for first-line or any resistance after travel to Oceania, because cells contained <5 travelers.
Figure 2.
Figure 2.
Percentage of patients with nontyphoidal Salmonella (NTS) infection reporting taking select antimicrobials (numbers displayed at ends of bars), by predicted susceptibility and international travel within 7 days before illness began in 2018–2019. Predicted resistance to an antibiotic is defined as the presence of a resistance gene or mutation conferring decreased susceptibility to that antibiotic. Third-generation cephalosporins include ceftriaxone.
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