Comparative studies on Clostridium botulinum type A strains associated with infant botulism in Japan and in California, USA.

Twenty strains of Clostridium botulinum type A associated with infant botulism cases, six in Japan and 14 in California, USA, were compared in their characters. All six Japanese strains produced medium-sized progenitor toxin (M toxin; Mr 300 k) but no hemagglutinin and showed lower 50% infective doses (ID50) in the infant mouse test; whereas most American strains produced large-sized progenitor toxin (L + LL toxins; Mr 500 k and 900 k) and hemagglutinin in addition to M toxin and showed higher ID50 in infant mice. No marked difference in the biochemical properties was found between the two groups except for two American strains.