TABLE 1.

Infection of enteric E. coli strains with φ3538(Δstx₂::cat) and production of lysogens

Bacterial strain	Serotype	stx geno-typea	MIC (μg/ml)b	E. coli group	Source or referencec	Result of infection with φ3538(Δstx2::cat)d
						Plaque formation on mitomycin-LB	Growth of infected cells on Cam-LB	PCR for detection of lysogense	Inducibility of lysogens with mitomycin	Plaque hybridi-zation with cat probe (%)f
11-1/87	O111:H2	−	3.0	EPEC	SC	−	+	+	+	+ (0.5)
6416/87	O26:H−	−	4.0	EPEC	SC	−	+	+	+	+ (0.1)
EDL933	O157:H7	1, 2	4.0	STEC	23	−	+	+	+	+ (2.0)
778/98	O157:H7	1, 2	4.0	STEC	SC	−	+	+	+	+ (0.2)
3574/92	O157:H7	2	3.0	STEC	28	−	+	+	+	+ (52.0)
2987/98	O157:H7	1, 2, 2c	4.0	STEC	SC	−	+	+	+	+ (0.1)
1249/87	O157:H7	2, 2c	3.0	STEC	28	−	+	+	+	+ (63.0)
1658/91	O157:H7	2, 2c	3.0	STEC	28	−	+	+	+	+ (10.0)
1193/89	O157:H−	1	3.0	STEC	28	−	+	+	+	+ (82.0)
7513/91	O157:H−	2c	3.0	STEC	28	−	+	+	+	+ (60.0)
5291/92	O157:H−	1, 2c	3.0	STEC	28	−	+	+	+	+ (53.0)
427/89	O157:H−	1, 2c	2.0	STEC	SC	−	+	+	−	NPg
3901/97	O26:H−	1, 2	3.0	STEC	SC	−	+	+	+	+ (30.0)
DEF 53	O111:HND	−	4.0	EAEC	AG	−	+	+	+	+ (0.2)
4140-86	O44:HND	−	3.0	EAEC	SC	−	+	+h	NP	NP
12860	O124:HND	−	1.0	EIEC	SC	+	+	+	+	+ (100.0)
7	NDi	−	4.0	PSj	SC	−	+	+	+	+ (15.0)
C600	ND	−	1.5	LSk	SC	+	+	+	+	+ (100.0)

^astx₁ was detected by amplification with primers KS7 and KS8 (32), and the stx₂ and stx₂c genes were both amplified with primers GK3 and GK4 and differentiated from each other by restriction analysis with HaeIII and FokI (28). −, stx negative. 

^bMIC of chloramphenicol for wild-type E. coli strains. 

^cSC, strain collection; AG, strain from Anna Giammanco, Palermo, Italy. 

^dMitomycin-LB, LB agar plates containing 0.5 μg of mitomycin per ml; Cam-LB, LB agar plates containing 30 μg of chloramphenicol per ml. 

^ePrimers HSB1 and HSB3 were used to amplify the cat gene within the Δstx₂::cat fusion in the genome of φ3538(Δstx₂::cat). 

^fPercentage of the total number of plaques present on matrix LB agar plates. 

^gNP, not performed. 

^hPCR was positive with a pool of colonies; a single PCR-positive colony was not found. 

ⁱND, not determined. 

^jPS, strain of physiological intestinal microflora. 

^kLS, laboratory strain.