OBJECTIVE  To analyze the clinical features and drug resistance trends of Shewanella-related surgical site infection (SSI), and to evaluate the mortality risk of patients through a combined prognostic model.

METHODS  A retrospective analysis was conducted on the clinical data of 45 patients with Shewanella-related SSI admitted to Yantai Yuhuangding Hospital from 2013 to 2023. Microbiological testing, drug susceptibility tests and a prognostic model plasma interleukin-6 (IL-6) combined with the Howell-PIRO score were used to summarize the infection characteristics, drug resistance and mortality risk.

RESULTS  A total of 45 Shewanella strains were isolated, including 32 Shewanella putrefaciens and 13 Shewanella algae. The infection patterns were predominantly mixed infections. Shewanella exhibited the highest resistance rate to ticarcillin-clavulanate (26.67%, 12/45), followed by cefoperazone/sulbactam (22.22%, 10/45) and ciprofloxacin (20.00%, 9/45). The combined prognostic model (IL-6+Howell-PIRO) demonstrated an area under the curve (AUC) of 0.935, with a sensitivity of 93.35% and a specificity of 92.14%, outperforming single indicators (P ＜ 0.05). Bioinformatics analysis revealed that Shewanella expressed various operons, such as those for bile hydrolysis and fatty acid metabolism, to adapt to the special environment of the biliary tract. It could express multiple antibacterial drug resistance genes, including β-lactamases and aminoglycoside-modifying enzymes. Siderophores may be one of its important virulence factors.

CONCLUSIONS  Shewanella may act as intestinal colonizing bacteria and cause SSI through surgical invasion. Its high resistance rates and mixed infection patterns can significantly increase mortality. It is recommended that hospitals in coastal areas optimize antibacterial drug regimens and use combined models to identify high-risk patients early.