Seasonality of Bacterial Strains in Diabetic Foot Osteomyelitis: Implications for Empiric Antibiotic Therapy in a Temperate Region with Distinct Seasons

<b>Background</b>: Diabetic foot osteomyelitis (DFO) is a severe complication requiring effective empiric antibiotic therapy to prevent amputation. While global guidelines suggest tailoring therapy based on climate zones, limited data exist regarding seasonal variations within a single region experiencing distinct seasonal extremes. This study investigated whether the bacterial etiology of DFO differs significantly between the hot, humid summer and the cold, dry winter in the Republic of Korea. <b>Methods</b>: We conducted a retrospective cohort study of 85 patients with DFO who underwent lower extremity amputation between January 2018 and October 2024. Patients were categorized into Summer (July-August) and Winter (December-January) groups. Deep tissue or bone specimens were analyzed to compare pathogen prevalence. <b>Results</b>: A total of 85 patients were included (Summer: <i>n</i> = 45; Winter: <i>n</i> = 40). While <i>Staphylococcus</i> species were the most common pathogens overall (30.6%), a seasonal shift was observed. The proportion of Gram-negative isolates was higher in Summer (50.7%) compared to Winter (35.1%), representing a notable clinical trend (<i>p</i> = 0.080). Specifically, <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i> were more frequently isolated during the summer months. Furthermore, polymicrobial infections were more prevalent in Summer (62.2%) compared to Winter (45.0%), although this did not reach statistical significance (<i>p</i> = 0.111). <b>Conclusions</b>: The microbiological profile of DFO exhibits seasonal variations. The observed trend toward an increased prevalence of Gram-negative and polymicrobial infections during the Korean summer suggests that empiric antibiotic guidelines should be dynamic rather than static.