The potential for a revolution in microbiol testing can be perceived with the near on-line detection of indicator microorganisms. By definition, these are microorganisms present in significant numbers within a food which, while not pathogenic, can be related through increasing count to the increased probability of pathogen contamination. We have used recombinant lux+ bacteriophage to detect enteric indicator bacteria without recovery or enrichment in 50 min, provided that they are present at levels greater than 104 g−1 or cm−2. After a 4-h enrichment, samples having enteric counts of 10 g−1 or cm−2 can be distinguished from background.