Examination of feces and serum for diagnosis of infant botulism in 336 patients.

In the 12-year period 1975 to 1987, feces from 336 infants were examined for botulinal neurotoxin and Clostridium botulinum. All the infants had illnesses which prompted their physicians to consider infant botulism in the diagnosis. Stool specimens from 113 of the infants yielded organisms that produced botulinal neurotoxins assumed to be responsible for the illness. The types of botulinal toxin in the confirmed cases were distributed as follows: 38 A, 69 B, 2 atypical B, 1 E, 1 F, 1 A + B, and 1 B + F. The type A and B toxins in a single infant were produced by two different strains of organism, and the type B and F toxins in another infant were produced by a single strain. The physiological characteristics of all the isolated toxigenic organisms except two were consistent with those of group I (proteolytic) C. botulinum. The toxigenic isolate from the infant with type E botulism was identified as C. butyricum, and that from the infant with type F botulism was identified as C. barati. Toxin of the same type as produced by the isolated organisms was identified in feces of 98 of 111 culture-positive infants. Botulinal toxin was identified in the serum of 9 of 67 culture-positive infants (8 of 22 infants with type A organisms; 1 of 43 infants with type B organisms; neither of 2 infants with A + B or atypical type B organisms). Botulinal toxin was not detected in feces (206 infants) or in serum (114 infants) of the culture-negative infants. The culture-positive infants had clinical features and a course of illness consistent with those of infant botulism. Most of the culture-negative infants probably had illnesses other than botulism, but specimens might have been obtained late in some infants' illnesses, when the organism had disappeared.