Analysis of clinical characteristics of infections caused by Shewanella species.

PURPOSE: The Shewanella genus is a rare pathogen of marine origin. In recent years, there has been a continuous increase in infection cases caused by this bacterium, and we have observed the uniqueness of infections caused by this microorganism.

MATERIALS AND

METHODS

This study conducted a retrospective analysis of the medical history and laboratory examination data of patients infected with the Shewanella genus over the past decade. Additionally, it employed bioinformatics methods to analyze the relevant virulence factors and antibiotic resistance genes associated with the Shewanella genus.

RESULTS

Over the past 10 years, we have isolated 51 cases of Shewanella, with 68.82% being Shewanella putrefaciens (35/51 cases) and 31.37% being Shewanella algae (16/51 cases). Infected individuals often had underlying diseases, with 39.22% (20/51) having malignant tumors and 25.49% (13/51) having liver and biliary system diseases primarily characterized by stones. The majority of patients, 62.74% (32/51), exhibited mixed infections, including one case with a combination of infections from three other types of bacteria and five cases with a combination of infections from two other types of bacteria. The identified microorganisms were commonly resistant to ticarcillin-clavulanic acid (23.5%), followed by cefoperazone-sulbactam (19.6%), ciprofloxacin (17.6%), and cefotaxime (17.6%). Bioinformatics analysis indicates that Shewanella can express bile hydrolysis regulators and fatty acid metabolism regulators that aid in adapting to the unique environment of the biliary tract. Additionally, it expresses abundant catalase, superoxide dismutase, and two-component signal transduction system proteins, which may be related to environmental adaptation. Shewanella also expresses various antibiotic resistance genes, including beta-lactamases and aminoglycoside modification enzymes. Iron carriers may be one of its important virulence factors.

CONCLUSIONS

We speculate that the Shewanella genus may exist as a specific colonizer in the human body, and under certain conditions, it may act as a pathogen, leading to biliary infections in the host.