Osteomyelitis in military personnel wounded in Iraq and Afghanistan.

Background: Orthopedic injuries occurring in Operations Iraqi Freedom and Enduring Freedom (OIF/OEF) are complicated by infections with multidrug resistant bacteria. We describe demographics and microbiology of OIF/OEF casualties with primary and recurrent osteomyelitis.
Methods: A retrospective cohort study was performed of OIF/OEF casualties admitted to our facility from February 1, 2003 to August 31, 2006. Electronic records were queried for demographic information, bacteria recovered, antibiotic therapies and duration, site of osteomyelitis, orthopedic devices, and outcomes.
Results: There were 110 patients with 139 hospitalizations for osteomyelitis; 94 involved lower extremities, 43 involved upper extremities, and 2 involved the axial skeleton. One hundred three admissions were initial episodes whereas 36 admissions were recurrences. The median age was 27 years; 95% were men. Duration of follow-up ranged from 2 weeks to 36 months. Those patients with orthopedic devices had recurrent infections more frequently (26 vs. 5%, p < 0.01). Bacteria, antibiotics, or infection site were not predictive of recurrence. Acinetobacter spp. (70 vs. 5%, p < 0.01), Klebsiella pneumoniae (18 vs. 5%, p = 0.04), and Pseudomonas aeruginosa (24 vs. 5%, p < 0.01) were more likely to be recovered during original episodes than during recurrences. Gram-positive organisms were more likely during recurrences; Staphylococcus aureus (13 vs. 53%, p < 0.01); methicillin susceptible S. aureus (5 vs. 22%, p < 0.01), methicillin resistant S. aureus (8 vs. 31%, p < 0.01).
Conclusions: The microbiology of osteomyelitis in veterans of OIF/OEF differs substantially depending upon whether the infection is new or recurrent. Gram-negative pathogens predominate early, being replaced with staphylococci after treatment, despite nearly universal use of gram- positive therapy.