TABLE 3.

Mortality, lesion scores, and recovery of challenge E. coli from infected chickens

Challenge E. coli	Mortality (%)	Mean lesion score ± SEM	Recovery of E. coli
			Directa	Totalb
Aerosol challenge
Wild-type Ec222	15	3.65 ± 0.65c	43/60	56/60
Ec222 vat deletion mutant	0	0.11 ± 0.07	9/60	32/60
Cellulitis challenge
Wild-type Ec222	33	5.0 ± 0.25c	12/12	NDd
Ec222 vat deletion mutant	0	0.01 ± 0	0/12	ND

^aNumber recovered by direct plating of swabs on MacConkey agar/total.

^bNumber recovered by culture of swabs in Trypticase soy broth followed by subculture on MacConkey agar/total.

^cSignificantly higher than that for lesions caused by infection with for Ec222 vat mutant. P = <0.0001. Maximum score was 7.0. Normal was scored as 0.01.

^dND, not done.