TABLE 2.

Heat resistance of spores produced by cpe-positive C. perfringens isolates^a

Isolate	Origin	D value at 100°C (min)
Food poisoning isolates carrying a chromosomal cpe geneb
NCTC 8239	Europe, 1950s	124
191-10	United States, 1990s	67
FD1041	United States, 1980s	32
E13	United States, 1960s	30
NCTC 10239	Europe, 1950s	45
Avgc		60.0 ± 18
Isolates carrying a plasmid cpe gene
F5603	Humans, Europe, 1980s	0.6
F4969	Humans, Europe, 1980s	0.5
NB16	Humans, Europe, 1980s	1.9
B40	Humans, Europe, 1980s	1.6
222	Veterinary, United States, 1990s	0.9
153	Veterinary, United States, 1990s	1.3
458	Veterinary, United States, 1990s	0.5
Avgc		1.0 + 0.3

^aThe results are averages based on the results of two experiments. The results were very reproducible for each isolate (data not shown). 

^bIsolate C1841 is not listed because this isolate did not sporulate in DS medium. 

^cAverage D value of each cpe genotype ± standard error.