Attachment of Salmonella strains to chicken skin. The amount of Salmonella attachment to chicken skin was determined by measuring the bioluminescence following 1 h incubation of bacterial suspension with quadruplicate skin samples. Bacteria numbers of each strain were estimated from the bioluminescence values using each strain's linear correlation formula. Unattached Salmonella were removed by gentle washing prior to bioluminescence measurements. The bacteria number for each strain is the geometric mean of four replicates from three separate experiments. Letters on the right of the graph indicate statistical groupings as determined by Tukey's test. Values with the same letter are not significantly different (P > 0.05).