Active surveillance for asymptomatic colonization with multidrug-resistant gram negative bacilli among injured service members--a three year evaluation.

In response to the high rates of colonization and infection by multidrug-resistant gram-negative bacilli (MDR GNB), many military treatment facilities (MTFs) have implemented additional infection control practices, such as active surveillance cultures for asymptomatic colonization. Results of surveillance cultures (June 2009 - May 2012) collected from patients at Landstuhl Regional Medical Center (Landstuhl RMC), Germany, and three U.S. MTFs were analyzed to evaluate trends in MDR GNB colonization over time and across facilities. At Landstuhl RMC, 6.6 percent of patients were colonized on admission with MDR GNB compared to 12.4 percent of patients admitted to the participating U.S. MTFs. Escherichia coli was the predominant organism, representing 82.4 percent of MDR isolates at Landstuhl RMC and 67.1 to 83.3 percent at U.S. MTFs. Other common MDR GNB included Acinetobacter calcoaceticus-baumannii complex and Klebsiella pneumoniae. Although Pseudomonas aeruginosa was often isolated from the surveillance cultures, it was never multidrug-resistant. Annual rates of MDR GNB colonization were not significantly different over the three-year period. Ongoing research includes assessment of predictive factors for MDR GNB colonization and the relationship between colonization and infection.