Travel-associated multidrug-resistant organism acquisition and risk factors among US military personnel

J Travel Med. 2021 Mar 2:taab028. doi: 10.1093/jtm/taab028. Online ahead of print.


BACKGROUND: International travel is a risk factor for incident colonization with extended spectrum beta-lactamase (ESBL)-producing organisms. These and other multidrug-resistant (MDR) bacteria are major pathogens in combat casualties. We evaluated risk factors for colonization with MDR bacteria in US military personnel traveling internationally for official duty.

METHODS: TravMil is a prospective observational study enrolling subjects presenting to military travel clinics. We analyzed surveys, antimicrobial use data, and pre- and post-travel perirectal swabs in military travelers to regions outside the continental United States, Canada, Western or Northern Europe, or New Zealand, presenting to one clinic from 12/2015-12/2017. Recovered Gram-negative isolates underwent identification and susceptibility testing (BD Phoenix). Characteristics of trip and traveler were analyzed to determine risk factors for MDR organism colonization.

RESULTS: 110 trips were planned by 99 travelers (74% male, median age 38 years [IQR 31, 47.25]); 72 trips with returned pre- and post-travel swabs were completed by 64 travelers. Median duration was 21 days (IQR 12.75, 79.5). 17% traveled to Mexico/Caribbean/Central America, 15% to Asia, 57% to Africa, and 10% to South America; 56% stayed in hotels and 50% in dormitories/barracks. Travelers used doxycycline (15%) for malaria prophylaxis, 11% took an antibiotic for travelers' diarrhea (TD) treatment (fluoroquinolone 7%, azithromycin 4%). Incident MDR organism colonization occurred in 8 travelers (incidence density 3.5/1000 travel days; cumulative incidence 11% of trips [95% CI: 4%-19%]), all ESBL-producing E. coli. A higher incidence of ESBL-producing E. coli acquisition was associated with travel to Asia (36% vs 7%, P = 0.02) but not with travel to other regions, TD, or use of antimicrobials. No relationship was seen between fluoroquinolone or doxycycline exposure and resistance to those antimicrobials.

CONCLUSIONS: Incident colonization with MDR organisms occurs at a lower rate in this military population compared to civilian travelers, with no identified modifiable risk factors, with highest incidence of ESBL acquisition observed after South Asia travel.

PMID:33675647 | DOI:10.1093/jtm/taab028