TABLE 1.

PCR primers used in this study

Primer	Nucleotide sequence (5′ to 3′)a	Amplicon size (bp)	Use	Reference
O1-rfb	GCGTAAATATCTAAACGATTGCATTG, AAACTCAGTTTCGAAGCGATCAA	83	Real-time PCR	13
ctxB	GCCGGGTTGTGGGAATGCTCCAAG, CATGCGATTGCCGCAATTAGTATGGC	536	PCR, sequencing	16
rstRET	GAGCTAAAATACAGCAACCAATGC, ACTCACCTTGTATTCG	487	PCR	17
rstRC	TATTGGGATTGTAAACAGCTGTCC, ACTCACCTTGTATTCG	480	PCR	18
tcpA 72F	CACGATAAGAAAACCGGTCAAGAG			19
tcpA 477R	CGAAAGCACCTTCTTTCACGTTG	451 (El Tor)	PCR	19
tcpA 647R	TTACCAAATGCAACGCCGAATG	620 (classical)	PCR	19
rtxC	CGACGAAGATCATTGACGAC, CATCGTCGTTATGTGGTTGC	265	PCR	4

^aIn entries with two sequences, the sequence for the reverse primer follows that for the forward primer.