Genetic variability among isolates of Plesiomonas shigelloides from fish, human clinical sources and fresh water, determined by RAPD typing

Plesiomonas shigelloides has been a suspected pathogen for the past 40 years. Random amplified polymorphic DNA (RAPD) analysis with two random primers was used to examine the genetic diversity among 26 strains of P. shigelloides: 10 from fresh water, 6 from fish, and 10 from human clinical sources. There was notable genetic variability among most of the isolates, and none of the isolates had the same composite RAPD profile. Our results indicate that most of the isolates from the same source grouped together and that the isolates from fish had a closer linkage to the human clinical isolates than did the freshwater isolates, suggesting that fish may be the more serious source for potential risk of infection. We also found that certain human clinical isolates had almost the same RAPD profiles as certain of the isolates from freshwater and fish, indicating that P. shigelloides from both sea food and freshwater should be considered potential pathogens.