VIRULENCE FACTORS IN AEROMONAS SPP AND THEIR ASSOCIATION WITH GASTROINTESTINAL-DISEASE

Culture filtrates of eight Aeromonas strains isolated from the feces o f 487 subjects (292 diarrhoeic patients and 195 asymptomatic subjects) were tested for toxin production in CHO and McCoy cells, and adhesion and invasive ability in Caco-2 cells. Among these isolates, three Aer omonas sobria and one Aeromonas caviae strains possessed virulence-ass ociated properties. Toxin production was the most common of the three virulence properties. Two A. caviae were associated, in the absence of other diarrhoeagenic agents, with gastroenteritis; however, a virulen ce marker (cytotoxin) was recognized only in one strain. Two strains o f A. sobria isolated from subjects with gastroenteritis were shown to be associated with one (cytotoxicity) or two (adhesion and invasive ab ilities) virulence factors, respectively. However, a third strain of A . sobria, although cytotoxic and invasive, was isolated from an asympt omatic subject. The results show that Aeromonas spp may act as human e nteric pathogens, but also indicate that the significance of several p utative virulence factors, such as production of cytotoxin and the cap acity to adhere to and invade mammalian cells, remains controversial i n explaining the enteropathogenesis of Aeromonads and therefore needs further studies.