Expression of hemolytic activity by Plesiomonas shigelloides

Abstract

More than 90% of the Plesiomonas shigelloides strains that we tested produced a β-hemolysin, as judged by the results of agar overlay and contact-dependent hemolysis assays. The hemolysin was cell associated, was active against the erythrocytes of various animal species, and was synthesized at both 25 and 35°C. Activity was lost after thermal or proteolytic treatments or after preincubation in the presence of gentamicin; hemolytic activity did not appear to correlate with the previously established 50% lethal doses for seven of these strains. The hemolysin may play a role in iron acquisition in vivo via the lysis of erythrocytes, liberating hemoglobin, or, alternatively, may be involved in gastrointestinal disease.