Reversion assays with strains carrying different <i>penA</i> alleles.

<p>A. Reversion assays. The strains with the <i>penA</i> mutations TR11, TR10, Cys69Tyr, and Asp179Asn were tested for their ability to undergo reversion. Serial dilutions of cells were spotted on selection plates containing amoxicillin (AMX), and spots of 10⁶ or 10⁵ cells from which revertant colonies arose (from the TR mutants) are shown. B. Reversion frequencies. Each measurement was plotted, and the mean value is denoted by a red line.