Prevalence of Clostridium botulinum in Retail Peanut Butters from a 2007 Survey in Ottawa, Canada.

The spore-forming, anaerobic bacterium, Clostridium botulinum, can cause intestinal toxemia (colonization) botulism in adults and infants by colonizing the gut and producing botulinum neurotoxin in situ. In 2006, peanut butter was identified as a lab-confirmed source of C. botulinum spores for an adult colonization botulism case in Canada. It is recommended for infants to be exposed to peanut butter at an early age to help prevent the development of a peanut allergy, yet the prevalence of C. botulinum in retail peanut butters is currently unknown. This report details a survey that was conducted in 2007 for the presence of viable C. botulinum spores in 92 peanut butters and 12 other nut butter spreads obtained from retail grocery stores in Ottawa, Canada. Samples were tested for viable C. botulinum spores by detecting botulinum neurotoxin in enrichment cultures by mouse bioassay. Three of the peanut butters from the entire survey of nut butter spreads (3/104, 3%) produced cultures containing botulinum neurotoxin. Whole genome sequencing performed on one isolate from this survey, as well as a clinical isolate and peanut butter isolates associated with the 2006 adult colonization case revealed that all C. botulinum isolates contained a full-length chromosomal bont/A1 gene within an ha-orf + cassette. This study identifies retail peanut butters as a potential source of viable C. botulinum spores at the time of sampling. Whether peanut butter represents a food category that may be contributing to the incidence of infant botulism has yet to be determined.