TABLE 5.

In vitro competition assays of APEC χ7122 isogenic mutants versus χ7122 ΔlacZYA derivative strain QT51

Genotype of competitor strain	Normalized coculture ratioa
	24 h	48 h
ΔpstCAB	4.7 ± 1.8	12.3 ± 4.3
ΔpstC	3.3 ± 0.7	4.1 ± 0.4
ΔphoR	1.6 ± 0.4	1.9 ± 0.7
ΔphoB	1.3 ± 1.1	0.6 ± 0.4
ΔpstC ΔphoB	1.4 ± 0.6	1.5 ± 0.2

^aData presented are the means ± standard deviations for three independent experiments. Equal quantities of χ7122 ΔlacZYA derivative strain QT51 and either mutant were grown in LB coculture. Viable counts (in CFU) were determined for the input time point, 24 or 48 h, by plating dilutions on MacConkey-lactose agar plates without antibiotics. The coculture ratio was calculated as the CFU of the QT51 mutant strain divided by the CFU of the competitor strain divided by the same ratio in the initial input inoculum.