Comparison of ELISA Technologies for Detection of C. botulinum Toxins A, B, E, and F in Foods

Introduction: Clostridium botulinum toxin (BoNT) is a powerful neurotoxin that causes severe foodborne illness, including botulism, in humans. Seven types of neurotoxins have been identified in Clostridium botulinum, but only types A, B, E, and F are known to cause disease in humans. Effective commercially available validated kits for these BoNT types are necessary in the event of a large scale food emergency involving BoNT. 

Purpose: This study was a parallel comparison between the DIG-ELISA C. botulinumtoxin kits and the commercially available Tetracore ELISA A, B, E, and F kits for detection of BoNT in foods.

Methods: Six brands each of canned chili, sausage, and luncheon meat were fortified at five levels of BoNT A, B, E, and F, and cold stressed overnight. Each sample was replicated eight times over four days. Samples were homogenized with GBS and toxins were extracted via centrifugation. The aqueous layers were filtered, prepared, and analyzed in parallel according to manufacturer’s instructions on the Tetracore and DIG-ELISA methods for each toxin specific type.

Results: Limit of Detection (ng/g) of BoNT Types A, B, E, and F in Foods

ELISA Method	Chili				Luncheon Meat				Sausage
	A	B	E	F	A	B	E	F	A	B	E	F
Tetracore	25	5-10	5	5	>50	50	500	5	>50	50	100	5
DIG	10	>50	5	5	10-25	>50	5	5	10-50	>50	5	5

Significance: While the DIG-ELISA method was more sensitive in the detection of toxin type A in all matrices, the detection limits of toxin types E and F were comparable in both methods.  The Tetracore ELISA method exhibited greater sensitivity in the detection of toxin type B in all matrices evaluated.