Alexander Gill, Tanis McMahon, Forest Dussault, Karen Jinneman, Rebecca Lindsey, Haley Martin, Devon Stoneburg, Nancy Strockbine, June Wetherington, Peter Feng
Two outbreaks of Shiga toxin-producing Escherichia coli O121:H19 associated with wheat flour, in the United States of America and Canada, involved strains with an unusual phenotype, delayed lactose utilization (DLU). These strains do not ferment lactose when initially cultured on MacConkey agar (MAC), but lactose fermentation occurs following subculture to a second plate of MAC. The prevalence of DLU was determined by examining the β-galactosidase activity of 49 strains of E. coli O121, and of 37 other strains of E...
April 2022: Food Microbiology