The O antigens used to serogroup Shigella are also used to serogroup which other organism?

The O antigens used to serogroup Shigella are also used to serogroup which other organism?

• A. Escherichia coli
• B. Staphylococcus aureus
• C. Pseudomonas aeruginosa
• D. Bacillus cereus

Answer: (A)

O antigens are the polysaccharide components of the LPS on the surface of many Gram-negative bacteria, and serogrouping is based on those surface sugar patterns. Shigella uses its O antigens to define serogroups, and those same O antigen structures are found in Escherichia coli. Because Shigella and E. coli share closely related LPS O-antigen configurations, the antisera that identify Shigella O groups also recognize the corresponding E. coli O groups. That’s why the O antigens used to serogroup Shigella are also used to serogroup Escherichia coli. Other organisms listed are not classified by this shared O-antigen system in routine clinical serotyping.

O antigens are the polysaccharide components of the LPS on the surface of many Gram-negative bacteria, and serogrouping is based on those surface sugar patterns. Shigella uses its O antigens to define serogroups, and those same O antigen structures are found in Escherichia coli. Because Shigella and E. coli share closely related LPS O-antigen configurations, the antisera that identify Shigella O groups also recognize the corresponding E. coli O groups. That’s why the O antigens used to serogroup Shigella are also used to serogroup Escherichia coli. Other organisms listed are not classified by this shared O-antigen system in routine clinical serotyping.