Oxytetracycline–glucose–yeast extract agar (OGYA), gentamicin–glucose–yeast extract agar (GGYA) with the antibiotic added separately or sterilized with the medium, chlortetracycline–Rose Bengal agar (CRA), chloramphenicol‐streptomycin agar (PYA) and to a lesser extent, oxytetracycline–gentamicin–glucose–yeast extract agar (OGGYA) with or without Rose Bengal added, have been compared for the selective enumeration of moulds in foods. The results obtained from dried cereal products show that the media are almost equally productive and selective when applied to such foods, but Rose Bengal limits the size of mould colonies. When examining fresh proteinaceous foods, such as minced meat and chicken, CR agars and to a certain extent gentamicin‐containing agars show the distinct advantage of being much more inhibitory towards the psychrotrophic Gram negative rods that predominate in the associated flora of such foods. Oxytetracycline–glucose–yeast extract agar lost its bacteriostatic properties when heavily challenged with proteinaceous substrates and/or incubated for longer periods at 37° or even at 25°. For such applications chloramphenicol was found to be the antibiotic of choice.
The bacteriological condition of 34 milk replacer products and 110 mixed animal feeds from feed mills in The Netherlands and U.K. was examined. The object of the survey was to provide guidelines for determining bacteriological standards to be applied to proteinaceous feed ingredients.Significant differences in counts were observed between milk replacers for calves, whether from Dutch or British sources, and mixed feeds for other animals, but, with one exception, i.e. the Enterobacteriaceae count, a striking similarity was found in the microbiological condition of the same type of product in both countries. From the data obtained, the conclusion that proteinaceous feed components manufactured according to good processing practices will meet the specifications indicated by the mean counts in Tables 2 and 3 appears justified.
The associations between traditional coliform/fecal coliform indicator tests and coliphage, Presence/Absence (P/A), A‐1 broth, and H2S paper strip tests are evaluated for Peruvian waters.
Drinking water samples showed that the P/A test was the most sensitive, producing the greatest number of positive results. In drinking water, in some of the samples, the only indicator organisms present were coliphage. The incidence of coliphage in these potable water supplies reflects the probability of human pathogenic viruses also surviving the treatment processes accorded those samples.
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