Longitudinal characterization of Acinetobacter baumannii-calcoaceticus complex, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus colonizing and infecting combat casualties

Drug-resistant Acinetobacter baumannii-calcoaceticus complex, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus colonize and infect combat casualties from Iraq and Afghanistan. We retrospectively evaluated relatedness, by pulsed-field gel electrophoresis and antibiotic susceptibility testing, of isolates colonizing and infecting casualties over 2 years. Colonizing organisms were unrelated to isolates producing later infection in up to 27% of cases; most isolates underwent change in antibiotic susceptibilities. The same is true for serial infecting isolates recovered during hospitalization.