Pathogenicity and virulence of Plesiomonas shigelloides

Background: Plesiomonas shigelloides is implicated in both intestinal and extra-intestinal infections in man and in animals. These microorganisms are widely distributed in environment and the isolates from water, food chain, different animals are described in several studies. P. shigelloides can be found in most aquatic environments from tropical to cold regions at the polar circle. The isolates revealed a wide range of serotypes and antibiotic susceptibility except the broad spectrum penicillins. Objectives: To analyse the factors of pathogenicity in P. shigelloides isolated from patients with intestinal and extra-intestinal infections, from animals, aquatic environment and food chain. Methods: For the detection of enterotoxin production the cell culture tests and for the endotoxin LAL test were applied. Surface hydrophobicity was evaluated by Congo red binding test, salt-aggregation test and bacterial cell adherence to xylene test. Motility and production of ß-hemolysin was evaluated as well. Several enzymes were included in the testing scheme together with a production of biofilm and signal molecules, the un-substituted N-acyl-homoserine lactones (AHLs). The studied isolates were serotyped by the scheme based on somatic and flagellar antigens developed by Aldova and Schubert. Results and Conclusion: The comparative analysis of the pathogenic factors profile in veterinary and human as well as in environmental isolates of P. shigelloides did show the production of multiple potential virulence factors that may play a role in the pathogenesis of the infections caused by this species. However, no dominating factor of pathogenicity was found in our studies thus strengthening the position of P. shigelloides as a challenging microorganism.