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Applied and Environmental Microbiology, April 2002, p. 1631-1638, Vol. 68, No. 4
0099-2240/02/$04.00+0 DOI: 10.1128/AEM.68.4.1631-1638.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Pôle Santé-Aliment-Nutrition, Institut Pasteur de Lille, Domaine du Certia, F-59651 Villeneuve d'Ascq,1 Département de Microbiologie Alimentaire, Service Central d'Etudes et de Réalisation du Commissariat de l'Armée de Terre, 00447 Armées, France2
Received 30 July 2001/ Accepted 8 January 2002
A 24-h direct plating method for fecal coliform enumeration with a resuscitation step (preincubation for 2 h at 37 ± 1°C and transfer to 44 ± 1°C for 22 h) using fecal coliform agar (FCA) was compared with the 24-h standardized violet red bile lactose agar (VRBL) method. FCA and VRBL have equivalent specificities and sensitivities, except for lactose-positive non-fecal coliforms such as Hafnia alvei, which could form typical colonies on FCA and VRBL. Recovery of cold-stressed Escherichia coli in mashed potatoes on FCA was about 1 log unit lower than that with VRBL. When the FCA method was compared with standard VRBL for enumeration of fecal coliforms, based on counting carried out on 170 different food samples, results were not significantly different (P > 0.05). Based on 203 typical identified colonies selected as found on VRBL and FCA, the latter medium appears to allow the enumeration of more true fecal coliforms and has higher performance in certain ways (specificity, sensitivity, and negative and positive predictive values) than VRBL. Most colonies clearly identified on both media were E. coli and H. alvei, a non-fecal coliform. Therefore, the replacement of fecal coliform enumeration by E. coli enumeration to estimate food sanitary quality should be recommended.
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