Identification of a Rough Strain of <i>Escherichia coli</i> O157:H7 That Produces No Detectable O157 Antigen

Abstract

MA6, an O157:H7-like strain, did not react with most anti-O157 kits examined; however, it had the rfbE gene that is essential for O157 expression and carried O157:H7 virulence factors. Lipopolysaccharide analysis showed that MA6 is a rough strain that does not produce the O157 antigen, but genetically, it belongs in the O157:H7 clonal group.