Testing of a Chemiluminescence Enzyme Immunoassay for selective detection of E. coli O157 from ground beef samples

The aim of this study was to evaluate a Chemiluminescence Enzyme Immunoassay (CLIA) developed for the detection of E. coli O157:H7, using different E. coli O157 serotypes. The sensitivity and specificity of the kit were determined from the tenfold dilutions of the 24-hour broth cultures of the test strains. According to the results obtained in this trial, the sensitivity of the kit is 103–104 cells ml−1, and it is specific for E. coli O157. Twenty-five g ground raw beef samples were prepared and inoculated with E. coli O157:H7 at different CFU g−1. The samples were incubated in 225 ml of modified E. coli broth with novobiocin (mEC + n) at 42 °C for 4 h and the immunoassays were performed following the instructions of the manufacturer. According to the results obtained by the CLIA test 101–102 E. coli O157 g−1 can be detected from the sample. So this kit seems to be suitable for screening the samples before selective cultivation of E. coli O157:H7

Tejsav képződés kinetikájának vizsgálata glükóz és fruktóz bomlásánál lúgos közegben

Die Ergebnisse beweisen, dass der Zerfall des Hexosemolekiils zu Triosen auch beim alkalischen Zuckerabbau von Hexosen über das intermediäre 3- Desoxy-Hexososon erfolgt — ähnlich wie dies bereits früher bei der Karamelisierung der Fruktose beobachtet wurde — entweder so, dass das 3-DesoxyHexoson zu Glycerinaldehyd und Methylglyoxal zerfällt, oder auf die Weise, dass sich Metasaccharinsäure bildet, die dann zu Milchsäure und Glycerinaldehyd zerfällt. It has been shown that the fragmentation of hexoses to trioses takes place in an alkaline medium through the intermediate 3-deoxy-hexosone — similarly to the pathway of fructose breakdown in caramelisation. The 3-deoxy-hexosone either yields glyceraldehyde and methylglyoxal by direct cleavage or first isomerisation occurs and the formed metasaccharinic acid degrades to lactic acid and glyceraldehyde