DIRECT-DETECTION OF SHIGA-LIKE TOXIN-PRODUCING ESCHERICHIA-COLI IN-GROUND BEEF USING THE POLYMERASE CHAIN-REACTION

We recently reported the development and assessment of a technique for the detection of Shiga-like toxin-producing Escherichia coil (SLTEC) using the polymerase chain reaction (PCR) and a digoxigenin-11-dUTP-la belled DNA probe. This technique has now been adapted for the direct i dentification of SLTEC in ground beef. Ground beef homogenates were di luted 1000-fold to reduce the concentration of components which inhibi t the thermostable polymerase. Assessment of four different ground bee f samples using the PCR detection technique revealed that fat content was a major inhibitory component. As few as 30 SLTEC ml(-1) of a groun d beef homogenate were detected using the PCR technique, although it w as necessary to enrich six of the samples for positive detection. Thes e findings indicate that the PCR detection technique is suitable for t he identification of SLTEC directly from contaminated ground beef with out isolation of the bacterium or purification of its DNA. (C) 1995 Ac ademic Press Limited