Table 2.

Isolation and characterization of fecal O157 VTEC strains from cattle from the four Dutch dairy farms investigated in the follow-up study

FarmDate of samplingNo. of cattle O157 VTEC positive/total no. of cattle (%)Phage typeResult of Vero cell assay for VTPCR results for the following:PFGE patternNo. of isolates
VT1VT2eae
IISept 199615/67 (22.4)8++++D15
Dec 19968/106 (7.5)8++++J7
8++++D1a
Mar 19970/99 (0.0)
Jun 19970/99 (0.0)
Sept 199736/59 (61.0)21+++K35b
54+++L1
Nov 199715/104 (14.4)21+++K15c
VOct 199617/83 (20.5)14+++G17
Jan 19971/83 (1.2)14+++G1d
Apr 19972/79 (2.5)4+++M2e
Jun 19979/52 (17.3)14+++N8f
48g +++N1
Sept 19972/38 (5.3)14+++O1h
54+++P1
Nov 19970/41 (0.0)
VIIINov 19960/100 (0.0)
Jan 19970/129 (0.0)
Apr 19971/131 (0.8)4+++M1
Jul 19970/99 (0.0)
Sept 19970/81 (0.0)
Nov 19970/110 (0.0)
XNov 19960/73 (0.0)
Feb 19970/73 (0.0)
Apr 19970/64 (0.0)
Sept 19972/22 (9.1)34+++Q2
Nov 19971/74 (1.4)34+++Q1
  • a Isolate from a calf 4 to 12 months of age which also tested positive in September 1996.

  • b 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.

  • c 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.

  • d Isolate from a calf 4 to 12 months of age which also tested positive in October 1996.

  • e Including an isolate from an adult cow which also tested positive in October 1996.

  • f Including an isolate from a calf 4 to 12 months of age which also tested positive in October 1996.

  • g Phage type 48 differs from phage type 14 in only one phage reaction.

  • h Isolate from an adult cow which also tested positive in October 1996 and April 1997.