[Clostridium botulinum in Costa Rica soils]

Thirty soil samples from the Pacific Dry Forest, the Caribbean lowlands and the Central Plateau of Costa Rica yielded seven cases with botulinal toxins. Of these, five were type C, one A and one B. Type C samples were from the Dry Pacific coastal area, others from the Caribbean lowlands. C. botulinum was isolated from three out of seven positive soil samples. The main reason for the poor recovery of C. botulinum from toxigenic samples is attributable to a low concentration of spores in the samples, because the toxin detection method required ten bacterial spores. An association was found between the presence of C. botulinum and low contents of organic matter (p < 0.05), but not with pH or soil type (p > 0.05).