Antibody‐Based Detection of Acid‐Shocked, Acid-Adapted, and Apple Juice-Incubated Escherichia coli O157:H7

Abstract

Sandwich enzyme‐linked immunosorbent assays (sELISA) allow for rapid detection of Escherichia coli (E. coli) O157:H7. Acidic conditions similar to those in certain foods and juices may reduce the ability to detect E. coli O157:H7. Growth of E. coli O157:H7 at pH 4 compared to pH 5–7 reduced fluorescent signal at the lower bacterial concentrations without altering the range of detection. Both acid‐adaptation and a subsequent pH 7 incubation reversed sensitivity. Incubation in apple juice was not deleterious to sELISA detection. Exposure to acidic conditions can cause a small reduction in sELISA sensitivity used to detect E. coli O157:H7.

Keywords:

• E. coli O157:H7
• Immunoassay
• Acid stress
• Acid adaptation
• Apple juice
• Food protection

Acknowledgments

The authors wish to thank Drs. Marianne Kramer and Elizabeth Kearns, University of South Florida, for their methodological advice. Appreciation is also expressed to Dr. Harvey George and Joe Peppe at the Massachusetts Department of Public Health State Laboratory Institute for their kind donation of the E. coli O157:H7 strain used in this study. This research was supported by a grant from the Department of Defense (DAAD13‐00‐C‐0037).