Percentage of conventional PCR <i>Escherichia coli</i> O178 positives by season and slaughterhouse from 1,773 enrichments.

Percentage of conventional PCR Escherichia coli O178 positives by season and slaughterhouse from 1,773 enrichments.</p

Total number of generic <i>E</i>. <i>coli</i> (GEC), O178, O157, shiga toxin (<i>stx</i>) 1 and 2 specific gene fragments in samples from slaughterhouse A or B (calculated using droplet digital PCR).

In each comparison between slaughterhouse A and B there were significant differences in enumeration of gene fragments, denoted by symbol α. Note: *The red line is the average number of GEC, O178, O157, stx1 and stx2 at each slaughterhouse and the black line in the boxes is the median.</p

Total number of shiga toxin (<i>stx</i>) 1 and 2 specific gene fragments versus reduced O157 enumerations (-23% for non-STEC O157) for summer and winter across the sampling period.

<p>Each peak denotes a sample and the color (red = O157, blue = <i>stx</i>₁ and green = <i>stx</i>₂) indicates the target.</p

Proportion of O157, O178, shiga toxin (<i>stx</i>) 1 and shiga toxin 2 specific gene fragments in samples for A and B slaughterhouses calculated using droplet digital PCR enumerations and comparison of the average proportion of the target gene compared to generic <i>Escherichia coli</i> (GEC) in the samples.

Note: *Proportions are based on the total E. coli counts. **Red line is the average proportion for the group and black line in the boxes is the median. *** Symbol: α denotes a significant difference between O157 at site A and B and between the average proportion of O178 and O157 (P < 0.05).</p

Comparison of the average proportion for O178, O157, shiga toxin (<i>stx</i>) 1 and 2 for the two sampling sites, A and B for each season based on the total generic <i>E</i>. <i>coli</i> count.

<p>Note: * Symbol: α above specific gene fragment denotes a significant difference in enumerations between summer and winter for that target (<i>P</i> < 0.05).</p

Primer sequence and amplicon size for O178 conventional PCR screening and for Evagreen droplet digital PCR assays.

<p>Primer sequence and amplicon size for O178 conventional PCR screening and for Evagreen droplet digital PCR assays.</p