Detection methods that don't rely on identifying Escherichia coli O157:H7's O antigen may be needed to ensure that food and drinking water are safe from the potentially lethal bacteria.
In a recent study, researchers at the National Institute of Health Sciences in Tokyo reported that E coli O157:H7 can lose its O antigenicity after surviving long periods of stress and starvation. To mimic starvation, the Japanese researchers cultured 19 strains of the verotoxin-producing bacteria and then left three strains in distilled water for 21 months and 16 in phosphate-buffered saline for nearly 8 months. On testing with an agglutination kit and O157 antiserum, the researchers found that seven of the 19 strains had lost O antigenicity. Detection of O antigenicity is widely used to identify E coli O157:H7. Yet, even without that distinctive fingerprint, the E coli strains still produced verotoxin.
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