Table 3.

Increase in the densities of Stx phages in some of the samples evaluated before and after their propagation in host strains

Host strain	Parameter	Value for sample group
		Minced beef (25 samples)			Salad (18 samples)
		Geometric mean	Max	Min	Geometric mean	Max	Min
E. coli C600	No. of GCs before enrichment	5.00 × 102	1.78 × 105	1.00 × 102	1.08 × 102	7.53 × 102	1.82 × 102
	No. of GCs after enrichment	5.74 × 103	2.42 × 105	7.90 × 102	1.68 × 103	8.43 × 103	1.92 × 102
	GC increasea	4.35 × 103	2.34 × 105	3.79 × 102	1.52 × 103	7.48 × 103	2.81 × 103
	% positiveb	56			39
E. coli O157:H7 (stx negative)	No. of GCs before enrichment	3.73 × 102	7.70 × 103	1.43 × 102	2.38 × 102	2.98 × 103	1.82 × 102
	No. of GCs after enrichment	3.83 × 103	1.11 × 104	3.98 × 102	6.51 × 103	1.09 × 104	3.17 × 103
	GC increasea	2.40 × 103	1.09 × 104	2.89 × 102	6.03 × 103	1.05 × 103	2.97 × 103
	% positiveb	56			61
S. sonnei 866	No. of GCs before enrichment	3.72 × 102	3.44 × 103	1.03 × 102	2.58 × 102	7.53 × 102	2.00 × 102
	No. of GCs after enrichment	9.32 × 103	1.48 × 107	3.37 × 102	4.58 × 103	9.79 × 103	2.71 × 103
	GC increasea	6.93 × 103a	1.48 × 107	1.97 × 102	3.73 × 103	9.74 × 103	1.00 × 103
	% positiveb	52			65

^aShows the geometrical mean of the increase observed in those samples that have shown phage propagation.

^bPercentage of samples in which a significant (P < 0.05) increase in the number of Stx phages was observed after propagation in the host strain.