Application of Flow Cytometry for the Detection of Escherichia coli O157

Abstract

Direct detection of E. coli O157 by flow cytometry (FCM) was performed using heattreated E. coli O157 and FITC-labeled anti-E. coli O157 IgG. The flow cytogram which was obtained within 30 minutes revealed an obvious difference between E. coli O157 treated with and that untreated with FITC-labeled anti-E. coli O157 IgG. There was also a clear difference between E. coli O157 and other strains of E. coli than E. coli O157 in reaction with FITC-labeled IgG.
Among twelve other strains of E. coli tested, six strains exhibited agglutination titers ranging from 1 to 4. The same six strains also gave weakly positive results in FCM. It is therefore possible to count the numbers of E. coli bearing the O157 antigen by using FCM.