Table 3. PFGE patterns (n = 47) of 79 STEC O157:H7 from animal fecal, fly, and environmental samples at 7 selected state and county fairs, 2002 (livestock and fly isolates) and 2003 (environmental isolates)*.
| Fair code | Total isolates | PFGE patterns | Unique XbaI patterns (P1–P47) (sample type† - no. isolates) | Simpson D (95% CI)‡ |
|---|---|---|---|---|
| SF2 | 35 | 25 | P1 (F-5, B-2), P2 (B-2), P3 (B-2), P4 (B-2), P5 (B-2), P6–P25§ | 0.96 (0.92–0.99) |
| CF19 | 4 | 2 | P26 (B-1, P-1), P27 (E-2) | 0.67 (0.49–0.85) |
| CF20 | 9 | 5 | P28 (P-1, B-1, F-1), P29 (F-3), P30 (D-1),¶ P31 (B-1), P32 (D-1) | 0.83 (0.73–0.94) |
| CF22 | 14 | 6 | P33 (B-5, P-2), P34 (S-3), P30 (D-1),¶ P35 (B-1), P36 (B-1), P37 (B-1) | 0.74 (0.59–0.89) |
| CFB | 4 | 4 | P38 (Ef-1), P39 (B-1), P40 (B-1), P41 (S-1) | 1.00 (NA) |
| CFY | 4 | 4 | P42 (B-1), P43 (B-1), P44 (B-1), P45 (S-1), | 1.00 (NA) |
| CF16 | 9 | 2 | P46 (B-8),# P47 (B-1) | 0.22 (0.00–0.57) |
*PFGE, pulsed-field gel electrophoresis; STEC, Shiga-toxigenic Escherichia coli. †F, fly (pooled fly sample collected when livestock were present on fair grounds); B, beef cattle; P, pig; E, environment; D, dairy cattle; S, sheep; Ef, environment fly (pooled fly sample collected when fair grounds were closed to the public and no animals were present). ‡Probability that any 2 randomly selected isolates from a given fair have unique PFGE patterns. CI, confidence interval; NA, not available. §Twenty isolates from SF2 each with a unique PFGE pattern from the following samples: 16 beef cattle, 2 sheep, 1 pig, and 1 dairy cow. ¶Isolates from dairy samples at CF20 and CF22 were indistinguishable; fairs were geographically close to each other. #A Stool STEC O157 isolate from a human clinical case-patient (hemorrhagic colitis) who had visited this fair also had this PFGE pattern.