Abstract

Background The oral cavity is a key reservoir for pathogens that cause oral diseases and may disseminate systemically. This study aimed to characterize clinically isolated oral pathogens and assess the antibiotic resistance and virulence of predominant strains. Methods Clinical samples were collected from patients at a tertiary oral specialty hospital in Southwest China between 2018 and 2023, including secretions, sputum, pus, blood, and other oral-related specimens from patients with oral/maxillofacial tumors, jaw fractures, malocclusion, and fascial space infections. Klebsiella pneumoniae , the most frequent isolate, was analyzed for patient demographics, resistance genes, and virulence factors. Selected strains were inoculated into mice to assess their effects on gut homeostasis via histopathology. Results The most prevalent oral pathogens were Klebsiella pneumoniae , Staphylococcus aureus , Prevotella intermedia , Pseudomonas aeruginosa , and Acinetobacter baumannii . Most K. pneumoniae isolates were resistant to ampicillin. Nineteen carbapenem-resistant (CRKP) and 21 non-CRKP strains were further analyzed. Among CRKP isolates, bla KPC-2 was the dominant carbapenemase gene. In vivo experiments demonstrated that clinical K. pneumoniae strains could colonize the gut and impair intestinal integrity. Conclusion K. pneumoniae is frequently detected in oral oncology and trauma settings, underscoring the need for continuous surveillance of CRKP strains with enhanced virulence potential.