2/16/2016 Virulence Factors Contributing to C.perfringens Foodborne Illness Virulence Factors Contributing to C.perfringens Epidemiological evidence for enterotoxin Foodborne Illness causing foodborne illness ·Enterotoxin 1.Presence of C perfringens enterotoxin in Koch's postulate on a molecular basis was victim's feces fulfilled 2.Toxin causes serious intestinal effects in Sporulating but not vegetative cultures of animal models cpe-positive isolates induced fluid 3.Human volunteers feed enterotoxin get accumulation in animals sick with symptoms of C perfringens Expression of toxin is sporulation associated foodborne illness .Strains carrying a cpemutation did not cause 4.Intestinal inflammation caused by toxin illness producing strains can be neutralized with Complementation of the mutation restored virulence toxin-specific antiserum Virulence Factors Contributing to C.perfringens Virulence Factors Contributing to C.perfringens Foodborne Illness Foodborne Illness ·Enterotoxin Expression and release of enterotoxin -C.perfringens type A causes non-foodborne GI illnesses 1.Toxin is made only by sporulating >antibiotic-associated diarrhea vegetative cells >sporadic diarrhea 2.Toxin is not secreted by sporulating >veterinary diarrheas cells but is released when the cpe-positive strains causing foodborne toxicoinfections are genetically distinct mother cell lyses from those causing non-foodborne illness 3.Isolates make extremely large 、 cpe is located on the chromosome for toxicoinfections and on the plasmid for amounts of toxin other illnesses2/16/2016 7 Virulence Factors Contributing to C. perfringens Foodborne Illness • Epidemiological evidence for enterotoxin causing foodborne illness 1. Presence of Presence of C perfringens C. perfringens enterotoxin enterotoxin in victim’s feces 2. Toxin causes serious intestinal effects in animal models 3. Human volunteers feed enterotoxin get sick h fwit symptoms of C. f per ringens foodborne illness 4. Intestinal inflammation caused by toxin producing strains can be neutralized with toxin-specific antiserum Virulence Factors Contributing to C. perfringens Foodborne Illness • Enterotoxin - Koch s postulate on a ’s postulate on a molecular basis was fulfilled - Sporulating but not vegetative cultures of cpe-positive isolates induced fluid accumulation in animals - Expression of toxin is sporulation associated - Strains carrying a cpe mutation did not cause illness - Complementation of the mutation restored virulence Virulence Factors Contributing to C. perfringens Foodborne Illness • Enterotoxin - C. perfringens type A causes non-foodborne GI illnesses  antibiotic-associated diarrhea  sporadic diarrhea  veterinary diarrheas - cpe-positive strains causing foodborne toxi if i co nfections are geneti ll di i ically distinct from those causing non-foodborne illness - cpe is located on the chromosome for toxicoinfections and on the plasmid for other illnesses Virulence Factors Contributing to C. perfringens Foodborne Illness • Expression and release of enterotoxin 1. Toxin is made onl yyp g b y s porulatin g vegetative cells 2. Toxin is not secreted by sporulating cells but is released when the mother cell lyses 3. Isolates make extremely large amounts of toxin