Attachment Strength to Pork Skin and Resistance to Quaternary Ammonium Salt and Heat of Escherichia coli Isolates Recovered from a Pork Slaughter Line

The aim of this study was to determine whether the attachment strength to pork skin, quaternary ammonium salt resistance, and thermal inactivation kinetics (at 65°C) of a range of Escherichia coli isolates could be correlated with their temporal stability (persistence) within a pork slaughter line. The genetic lineage of the E. coli isolates was determined using entero-bacterial repetitive intergenic consensus–PCR. The genotypes were divided into transient and endemic populations based on the number of times they were recovered within and across sampling visits made to a pork slaughterhouse. No significant variation in the D-value at 65°C (0.27 to 0.51 min) was observed among the genotypes tested. However, differences in D-values were found for 100 ppm quaternary ammonium salt (3.0 to 6.0 min). All of the E. coli genotypes attached strongly to pork skin, and a high proportion of cells were irreversibly bound (39 to 42% of the initial inoculum). However, variation among genotypes was found with respect to loose attachment (21 to 33% of inoculated cells). No correlation between persistence of E. coli genotypes within the slaughter line and attachment strength or quaternary ammonium salt resistance was found. Variation in either physiological attribute could not be predicted based on genetic lineage. Additional or alternative factors may contribute to the ability of E. coli populations to become endemic within pork processing facilities. More studies should be conducted to elucidate the underlying factors that promote the formation of endemic populations of E. coli and other enteric bacteria (e.g., Salmonella) within slaughter lines.