TABLE 2.
Isolation and characterization of fecal O157 VTEC strains from cattle from the four Dutch dairy farms investigated in the follow-up study
| Farm | Date of sampling | No. of cattle O157 VTEC positive/total no. of cattle (%) | Phage type | Result of Vero cell assay for VT | PCR results for the following:
|
PFGE pattern | No. of isolates | ||
|---|---|---|---|---|---|---|---|---|---|
| VT1 | VT2 | eae | |||||||
| II | Sept 1996 | 15/67 (22.4) | 8 | + | + | + | + | D | 15 |
| Dec 1996 | 8/106 (7.5) | 8 | + | + | + | + | J | 7 | |
| 8 | + | + | + | + | D | 1a | |||
| Mar 1997 | 0/99 (0.0) | ||||||||
| Jun 1997 | 0/99 (0.0) | ||||||||
| Sept 1997 | 36/59 (61.0) | 21 | + | − | + | + | K | 35b | |
| 54 | + | − | + | + | L | 1 | |||
| Nov 1997 | 15/104 (14.4) | 21 | + | − | + | + | K | 15c | |
| V | Oct 1996 | 17/83 (20.5) | 14 | + | − | + | + | G | 17 |
| Jan 1997 | 1/83 (1.2) | 14 | + | − | + | + | G | 1d | |
| Apr 1997 | 2/79 (2.5) | 4 | + | − | + | + | M | 2e | |
| Jun 1997 | 9/52 (17.3) | 14 | + | − | + | + | N | 8f | |
| 48g | + | − | + | + | N | 1 | |||
| Sept 1997 | 2/38 (5.3) | 14 | + | − | + | + | O | 1h | |
| 54 | + | − | + | + | P | 1 | |||
| Nov 1997 | 0/41 (0.0) | ||||||||
| VIII | Nov 1996 | 0/100 (0.0) | |||||||
| Jan 1997 | 0/129 (0.0) | ||||||||
| Apr 1997 | 1/131 (0.8) | 4 | + | − | + | + | M | 1 | |
| Jul 1997 | 0/99 (0.0) | ||||||||
| Sept 1997 | 0/81 (0.0) | ||||||||
| Nov 1997 | 0/110 (0.0) | ||||||||
| X | Nov 1996 | 0/73 (0.0) | |||||||
| Feb 1997 | 0/73 (0.0) | ||||||||
| Apr 1997 | 0/64 (0.0) | ||||||||
| Sept 1997 | 2/22 (9.1) | 34 | + | − | + | + | Q | 2 | |
| Nov 1997 | 1/74 (1.4) | 34 | + | − | + | + | Q | 1 | |
Isolate from a calf 4 to 12 months of age which also tested positive in September 1996.
Including two isolates from adult cows >3 years of age which also tested positive in September 1996 and three isolates from cattle ages 2 to 3 years which also tested positive in December 1996.
Including one isolate from a calf younger than age 4 months and three isolates from calves 4 to 12 months of age which all also tested positive in September 1997, one isolate from a heifer 1 to 2 years of age which also tested positive in December 1996, and one isolate from a heifer 1 to 2 years of age which also tested positive in September 1996.
Isolate from a calf 4 to 12 months of age which also tested positive in October 1996.
Including an isolate from an adult cow which also tested positive in October 1996.
Including an isolate from a calf 4 to 12 months of age which also tested positive in October 1996.
Phage type 48 differs from phage type 14 in only one phage reaction.
Isolate from an adult cow which also tested positive in October 1996 and April 1997.