Expression of flhDC in response to nutrient deprivation/osmotic shock and chlorine treatment. Relative expression of flhDC was normalised to the expression of the reference gene, rpoA. The expressions of flhDC were compared between uspC–IS30–flhDC-negative E. coli strain H51 and the two uspC–IS30–flhDC-positive strains WW10 and WW63 after 24 h TSB culture, nutrient deprivation/osmotic stress and chlorine treatment. The results demonstrate that there was no significant difference in flhDC expression between wild-type strain H51 and uspC–IS30–flhDC-positive strains WW10 or WW63 after 24 h TSB culture or after nutrient deprivation/osmotic stress (p value > 0·1). However, a significant difference (p value < 0·1 (asterisk)) in flhDC expression between the wild-type human strain H51 and the WW10 (p value = 0·06) or WW63 (p value = 0·08) after chlorine treatment was observed. The relative expressions of flhDC of WW10 and WW64 increased 3·6- and 2·6-fold compared to that of the H51 human strain, respectively