Natural history of colonization with gram-negative multidrug-resistant organisms among hospitalized patients.

OBJECTIVE

To determine the anatomic sites and natural history of colonization with gram-negative multidrug-resistant organisms (MDROs).

DESIGN

Prospective, longitudinal cohort study.

SETTING

Walter Reed Army Medical Center, a 236-bed tertiary care center in Washington, DC.

PATIENTS

Deployed subjects (ie, inpatients medically evacuated from Iraq or Afghanistan) or nondeployed subjects admitted to the same hospital.

METHODS

Consenting patients had 6 anatomic sites cultured every 3 days for 2 weeks and then weekly. Gram-negative organisms resistant to 3 or more classes of antibiotics were considered MDROs. Isolates were genotyped using pulsed-field gel electrophoresis. Clinical data, data on antibiotic use, and clinical culture results were collected.

RESULTS

Of 60 deployed subjects, 14 (23%) were colonized with an MDRO at admission, and 13 (22%) had incident colonization during hospitalization. The groin was the most sensitive anatomic site for detecting MDRO colonization, and all but one subject remained colonized for the duration of their hospitalization. Sixty percent of subjects with incident Acinetobacter colonization and 25% of subjects with incident Klebsiella colonization had strains that were related to those isolated from other subjects. Of 60 nondeployed subjects, 5 (8%) were colonized with an MDRO at admission; all had recent healthcare contact, and 1 nondeployed subject had an isolate related to a strain recovered from a deployed subject.

CONCLUSIONS

Colonization with gram-negative MDROs is common among patients with war-related trauma admitted to a military hospital and also occurs among nondeployed patients with recent healthcare contact. The groin is the most sensitive anatomic site for active surveillance, and spontaneous decolonization is rare.