Usefulness of bifidobacteria for the detection of faecal contamination in milk and cheese

Abstract

-Research of faecal contamination is most often based on the research of Escherichia coli, a rather unspecific marker showing both survival and multiplication outside the intestinal tract. When researching a more specific and sensitive marker, we examined human and cow's faeces, raw milk and dairy products for the presence of E. coli, but also bifidobacteria. In 146 human faecal samples, bifidobacteria were present at a mean level of 7.7 log cfu·g -1 , and the identified species were B. bifidum, B. longum, B. adolescentis and B. infantis. E.coli was present at a level of 6.9 log cfu·g -1 . In 30 samples of cow's faeces, the highest count of bifidobacteria was 8 log cfu·g -1 , while E. coli was present at a level of 6 log cfu·g -1 . Among 15 samples of cheese prepared with raw milk, bifidobacteria were found in 14 samples at levels comprising between 2 and 5 log cfu·g -1 . E. coli was never found (detection level 2 log cfu·g -1 ). Analysis of 207 samples of raw cow's milk sampled on the teat allowed isolation of bifidobacteria in 90% and E. coli in 68% of samples. Among 66 samples of raw milk sampled in refrigerated tanks, bifidobacteria were isolated in 95% and E. coli in 86%. In all cow's samples (faeces, milk and cheese), one distinct species was identified: Bifidobacterium pseudolongum var globosum. Levels of bifidobacteria are higher than values of E. coli in both human and animal faeces and raw milk, underlining the choice of bifidobacteria as a valid marker for faecal contamination of dairy products. Identification of bifidobacterial species even allows the determination of the origin (animal or human) of contamination.Bifidobacterium / E. coli / faecal contamination / raw milk Résumé -La recherche des bifidobactéries comme indicateur d'une contamination fécale dans les produits laitiers. La recherche d'une contamination fécale est le plus souvent basée sur la mise en évidence d'Escherichia coli, marqueur peu spécifique, car capable de survivre et de se multiplier en dehors du tractus digestif. À la recherche d'un marqueur plus spécifique et sensible, nous avons recherché dans des matières fécales humaines et bovines, du lait cru et des produits laitiers, la présence d'E. coli et de Bifidobacterium. Dans 146 matières fécales humaines, les bifides sont présents à un taux moyen de 7,7 log ufc·g -1 , les espèces identifiées sont B. bifidum, B. longum, B. adolescentis et B. infantis. E. coli est présent à un taux de 6,9 log ufc·g -1 . Dans 30 échantillons de bouses, le taux le plus élevé de Bifidobacterium est de 8 log ufc·g -1 alors qu'E. coli est présent à un taux de 6 log ufc·g -1 . Parmi 15 échantillons de fromage au lait cru, les bifides sont retrouvés dans 14 échantillons à des taux entre 2 et 5 log ufc·g -1 . E. coli est toujours en dessous du seuil de détec-tion (< 2 log ufc·g -1 ). L'analyse de 207 échantillons de lait cru pris à la mamelle a permis l'isolement des bifides dans 90 % et d'E. coli dans 68 % des échantillons. L'analyse de 66 échantillons de lait cru prélevés dans les tanks réfri...

Changes in Bacterial Profile During Amebiasis: Demonstration of Anaerobic Bacteria in Ala Pus Samples

“…28 This was also supported by a study carried out with human fecal samples in which bifidobacteria were present in higher number than E. coli. 29 No significant change was observed in P. productus or Ruminococcus titers among the various categories of individuals tested. Members of these genera are likely to be resistant both to drug action as well as E. histolytica infection.…”

Evaluation of the Hygienic Quality of Raw Milk Based on the Presence of Bifidobacteria Spp. As an Indicator of Faecal Contamination in Assiut City

“…Raw milk collected with proper hygiene should not contain Bifidobacteria. In fact, the presence of Bifidobacteria in raw milk indicates fecal contamination and poor farm hygiene (Beerens et al, 2000;Beerens and Neut, 2005). This bacterium has been recently proposed as a fecal indicator in water (Lynch et al, 2002;Gilpin et al, 2003 andNebra et al, 2003) and in meat and raw milk samples (Beerens, 1998;Gavini and Beerens, 1999;Beerens et al, 2000).…”