Table 1. Groups of strains studied for which statistical comparisons of repeat content and pathogenicity were performed.

		All strains (N = 126)			Strains with intact I-E genes (N = 71)
Comparison	Group of strains compared	No. of strains	Median repeat no.	Repeat no. range	No. of strains	Median repeat no.	Repeat no. range
A	1. Commensal	28	29.5	0–53	22	38.0	6–53
	2. Pathogenic	98	12	0–42	49	21.0	5–42
B	1. Commensal	28	29.5	0–53	22	38.0	6–53
	2. EnPEC	50	18	0–42	35	23.0	11–42
	3. ExPEC	43	2	0–29	11	19.0	5–29
C	1. EIEC	9	10	3–42	3	24.0	15–42
	2. EPEC	10	14	0–33	6	17.5	9–33
	3. ETEC	5	23	12–40	4	26.0	22–40
	4. EHEC	17	21	6–35	16	25.0	7–35
D	1. EnPEC (ECOR)	41	13	0–42	23	25.0	2–42
	2. EnPEC (non-ECOR)	31	14	0–40	18	19.0	2–40
E	1. n = 0 UPEC genes a	63	21	0–53	49	26	6–53
	2. n = 1 UPEC genes a	23	13	0–29	12	20.5	7–29
	3. n = 2 UPEC genes a	22	2	0–31	9	19	14–31
	4. n = 3 UPEC genes a	7	2	1–5	1	5	-
	5. n = 4 UPEC genes a	11	2	0–2	0	-	-

^aStrains with the same total number of UPEC factors considered in the study.