Article Abstract:
A novel assay combining immunomagnetic separation and a fluorescently stained bacteriophage for detecting Escherichia coli O157:H7 in broth cultures is described and evaluated. The fluorescent-bacteriophage assay (FBA) can detect 10(super 4) cells/ml, with the lower detection limit at between 10(super 2) and 10(super 3) cells/ml. Bacterial concentrations were not determined as the modified direct epifluorescent-filter technique proved to be unreliable for such a function. Results reveal that the FBA, when combined with flow cytometry, is a reliable technique for presumptive detection of E coli O157:H7 in broth.
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Article Abstract:
Research was performed regarding techniques used for the detection of 36 verotoxigenic Escherichia coli (VTEC), 5 VTEC, and 13 non-VTEC control cultures. Magnetic capture-hybridization PCR (MCH-PCR) was used to overcome the inhibitory effect of humic acid present in soil samples during PCR amplification while biotin-labeled DNA probes specific for verotoxigenic genes were used to capture the VTEC target DNA. MCH-PCR was fully capable of detecting 10 colony-forming units of VTEC per gram of ground beef with 15 h of nonselective enrichment.
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Article Abstract:
A study was conducted to determine whether the enterohemorrhagic Escherichia coli hemolysin gene ehxA is correlated to the serotypes of Shiga-like-toxin-producing Escherichia coli (SLTEC) found in human disease. The presence of ehxA and the virulence-associated genes eae, slt-I and slt-II in SLTEC isolates were determined using polymerase chain reaction amplification. Results suggest that the exhA is not necessary for virulence since some serotypes do not contain the gene.
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