H-NS controls metabolism and stress tolerance in Escherichia coli O157:H7 that influence mouse passage

BMC Microbiology

Table 4 Recovery of E. coli O157:H7 strains ATCC43895 (parent) and FRIK47001P (hns mutant) from feces following oral administration to ICR mice.^a

E. coli dose (CFU)	No. of mice with a positive fecal sample for E. coli O157:H7 in each trial with three mice inoculated per trial (total no. of positive mice/9 mice examined in 3 trials)
	Trial with log-phase cells			Trial with stationary-phase cells
	I	II	III	I	II	III
Strain 43895 (parent)
10²	0	0	1 (1)	0	1	3 (4)
10³	2	0	3 (5)	0	2	3 (5)
10⁴	3	1	3 (7)	3	3	2 (8)
Strain 47001P (hns mutant)
10²	0	0	0 (0)	0	0	0 (0)
10³	1	0	0 (1)	0	0	0 (0)^b
10⁴	0	0	0 (0)^c	1	0	0 (1)^c

^aCell pellets of the parent and hns mutant strains were resuspended and diluted to the appropriate cell number in 10% sucrose. Each mouse was administered 0.5 ml of the sucrose solution containing the designated dose of cells. Results are from fecal pellets collected 12–14 h after oral administration.
^bSignificantly different (p < 0.05) from results with the parent strain at a dose of 10³ CFU.
^cSignificantly different (p < 0.01) from results with the parent strains at a dose of 10⁴ CFU.

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