1388. Seasonality of Microbiology of Combat-related Wound Infections in Afghanistan

Abstract Background We examined the seasonality of wounds and wound infections, including occurrence of multidrug resistance, among combat casualties injured in Afghanistan. Methods The Trauma Infectious Disease Outcomes Study is a retrospective observational study of infectious complications among military personnel wounded during deployment (06/09-12/14). Wound cultures obtained ≤7 days following injury in Afghanistan were assessed. Epidemiologic, clinical, and microbiologic data were analyzed by injury season [winter (1 Dec-28/29 Feb), spring (1 Mar-31 May), summer (1 Jun-31 Aug), and fall (1 Sep-30 Nov)]. Multidrug-resistant (MDR) determinations for Gram-negative and Gram-positive organisms were per standardized definitions. Results The study population included 316 patients with a median of 3.5 (IQR 3-5) days from injury to initial culture. Gram-negatives (N=188, 59.5%) were more commonly isolated from wound cultures in summer (N=81, 43.1%) and fall (N=57, 30.3%) versus winter (N=18, 9.6%) and spring (N=32, 17%) (p< 0.001). The MDR Gram-negatives (N=69, 21.8%) were more common in summer (N=26, 37.7%), and fall (N=26, 37.7%) versus winter (N=3, 4.3%) and spring (N=14, 20.3%) (p=0.028). Wound infections were diagnosed in 198 (63%) patients. The pattern for infecting Gram-negative isolates (N=143, 72.2%, Table 1) was similar to that of overall Gram-negative isolates: summer (79.5%) and fall (83.6%; p< 0.001); MDR Gram-negatives (summer, 25.6%) and (fall, 41.8%; p=0.015). Escherichia coli and Enterobacter spp. were the most common infecting Gram-negative bacilli with no significant difference across the seasons. There was a higher proportion of infecting Acinetobacter baumannii isolates in the summer and fall compared to winter and spring. Infecting Gram-positive isolates (N=128, 65%) were not significantly different by season. Anaerobes associated with infections were also identified (N=30, 15%) with a higher proportion in the winter compared to summer, fall, and spring (p=0.036). Conclusion Gram-negatives, including MDR Gram-negative infecting organisms, were more common in summer/fall months in service members injured in Afghanistan. This may have implications for empiric antibiotic coverage during these months. Disclosures David R. Tribble, DrPH, AstraZeneca: The HJF, in support of the USU IDCRP, was funded to conduct or augment unrelated Phase III Mab and vaccine trials as part of US Govt. COVID19 response.