Virulence Factors of Aeromonas : A Genetic Characterization of Drinking Water Isolates

摘要

Microbiological surveys conducted by the U.S. EPA of finished drinking water utilities fromrnfour states, during 2000 / 2001, yielded 205 Aeromonas isolates. A Polymerase Chain basedrn(PCR) based genetic characterization of these isolates determined the presence of six virulencernfactor genes: elastase (ahyB), lipase (pla), the flagella A and B genes (fla) and three enterotoxinsrn(alt, act and ast). Primer sets were designed for all the target genes, except for act, which hadrnbeen published previously. PCR was performed in three duplex assays using the followingrnprimer sets together: elastase (ahyB) and lipase (pla); fla and alt ; act and ast. pla was presentrnin 86%, act in 69%, fla in 55%, ahyB in 40% and alt and ast in 45% and 30% of the strains,rnrespectively. Only one isolate had all six virulence genes. Multiple species were isolated fromrnmost of the utilities and different combinations of virulence factors were observed, sometimesrneven in different strains of the same species. However, a dominant strain having the same set ofrnvirulence factors, was usually isolated from different rounds of sampling from a single tap.rnThese results suggest the importance of examining as many Aeromonas isolates as possible fromrna water sample. The results indicate Aeromonas strains isolated from water utilities have thernpotential to be pathogenic, although, additional hitherto uncharacterized virulence factors may bernneeded to cause actual disease.