Open Access Highly Accessed Research article

Multidrug-resistant gram-negative bacteria colonization of healthy US military personnel in the US and Afghanistan

Todd J Vento12, David W Cole3, Katrin Mende14, Tatjana P Calvano1, Elizabeth A Rini1, Charla C Tully1, Wendy C Zera14, Charles H Guymon5, Xin Yu1, Kristelle A Cheatle1, Kevin S Akers125, Miriam L Beckius1, Michael L Landrum14 and Clinton K Murray12*

Author Affiliations

1 Brooke Army Medical Center/San Antonio Military Medical Center, Fort Sam Houston, TX, USA

2 Uniformed Services University of the Health Sciences, Bethesda, MD, USA

3 Blanchfield Army Community Hospital, Fort Campbell, KY, USA

4 Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Bethesda, MD, USA

5 United States Army Institute of Surgical Research, Fort Sam Houston, TX, USA

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BMC Infectious Diseases 2013, 13:68  doi:10.1186/1471-2334-13-68

Published: 5 February 2013



The US military has seen steady increases in multidrug-resistant (MDR) gram-negative bacteria (GNB) infections in casualties from Iraq and Afghanistan. This study evaluates the prevalence of MDR GNB colonization in US military personnel.


GNB colonization surveillance of healthy, asymptomatic military personnel (101 in the US and 100 in Afghanistan) was performed by swabbing 7 anatomical sites. US-based personnel had received no antibiotics within 30 days of specimen collection, and Afghanistan-based personnel were receiving doxycycline for malaria chemoprophylaxis at time of specimen collection. Isolates underwent genotypic and phenotypic characterization.


The only colonizing MDR GNB recovered in both populations was Escherichia coli (p=0.01), which was seen in 2% of US-based personnel (all perirectal) and 11% of Afghanistan-based personnel (10 perirectal, 1 foot+groin). Individuals with higher off-base exposures in Afghanistan did not show a difference in overall GNB colonization or MDR E. coli colonization, compared with those with limited off-base exposures.


Healthy US- and Afghanistan-based military personnel have community onset-MDR E. coli colonization, with Afghanistan-based personnel showing a 5.5-fold higher prevalence. The association of doxycycline prophylaxis or other exposures with antimicrobial resistance and increased rates of MDR E. coli colonization needs further evaluation.

Deployment; Malaria chemoprophylaxis; Environment exposure; ESBL-production; Escherichia coli