Genetic diversity and antimicrobial resistance among isolates of Escherichia coliO157: H7 from feces and hides of super-shedders and low-shedding pen-mates in two commercial beef feedlots

Table 4 Average group similarity of PFGE profiles by source of isolates compared by bootstrapping analyses (n = 1000) to the similarity of PFGE profiles for all isolates within a pen or across all pens

Feedlot	Pen	SS fecal PFGE similarity (%)	Signif^yof group	PS PFGE similarity (%)	Signif of group	LS fecal PFGE similarity (%)	Signif of group
Within pen
A	1	57.92	NS	59.94	NS	89.82	***
	2	62.18	NS	60.75	NS	72.80	***
	3	78.23	***	58.62	***	67.04	***
	4	85.92	***	68.59	***	72.70	***
	5	68.61	**	87.03	***	70.97	***
	6	60.08	NS	73.49	**	85.72	*
	7	IN^z	IN	IN	IN	IN	IN
B	1	69.72	***	64.81	***	66.19	***
	2	73.98	***	72.13	***	86.69	***
	3	77.66	***	68.89	***	88.99	***
	4	IN	IN	IN	IN	IN	IN
Across all pens		64.80	***	61.21	NS	64.91	***

SS fecal = fecal sample from super shedder (at least 10⁴ CFU/g feces); LS = fecal sample from low shedder (< 10⁴ CFU/g feces), PS = Perineal hide swab.
^ySignif, significance comparing group PFGE similarity with that of all isolates in a pen or across all pens, with *** = P < 0.001, ** = P < 0.01, * = P < 0.05, NS = P > 0.05.
^zIN, insufficient number of isolates for comparison, a minimum of 2 PFGE profiles per group are required.

ISSN: 1746-6148