TABLE 3.

Variation in E. coli O157 recovered at packing plants^a

Collection time and/or site	No. of isolates	No. of types	% Uniqueb
Preharvest	129	28	14.7
Feces	91	23	16.5
Hide	38	12	10.5
Postharvest	214	34	13.6
Preevisceration	148	28	13.5
Postevisceration	60	17	13.6
Final	6	5	16.7
Overall	343	47	14.0

^aIsolates were typed based on relatedness of XbaI PFGE genomic fingerprint patterns (see Materials and Methods). 

^bPercentage of unique isolates, or isolates unlike any other within the same lot.