FIG. 1.

Primers used for PCR and nested PCR. Conventional PCR was performed with the TR9-TR8 primer set as previously described. The first-round PCR was performed with the TB1-TB2 primer set amplifying 205-bp rpoB DNA. The second-round PCR was performed with the TB3-TR8 primer set to amplify 157-bp DNA from the first-round PCR product. Numbers indicate rpoB codons of E. coli.