[First outbreak of botulism caused by Clostridium botulinum subtype Af]

In December 1982 an outbreak of foodborne botulism presumably produced by the ingestion of home-made pickled trout occurred in San Rafael, province of Mendoza, Argentina. The toxin detected in blood serum and feces samples of the sole affected patient was preliminarily typed as a plain type A. A strain of Clostridium botulinum was isolated from feces which, after culture by the dialysis method, produced 1 x 10(7) LD50/mouse per ml. Quantitative neutralization tests carried out at different levels of toxin concentration, showed that this toxin consists of a major type A antigenic component (about 99% of the complex) and a minor type F component, defining its identity as a subtype Af. A rabbit antiserum obtained from this toxin neutralizes A and F reference toxins. Despite the antitoxic and supportive treatment, the patient died as a consequence of the poisoning. The polyvalent antiserum administered contained A, B and E antitoxins. Death could be due to the lethal effect of the A fraction, the F fraction or to a combined effect of both toxic components of the toxin. This is the first detection of an outbreak produced by C. botulinum subtype Af, serotype described in Argentina fifteen years ago, and not detected until now in other parts of the world.(ABSTRACT TRUNCATED AT 250 WORDS)