NCBI ROFL: Before you trust the five-second rule, read this.

By ncbi rofl | April 5, 2011 7:00 pm

Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule.

“AIMS: Three experiments were conducted to determine the survival and transfer of Salmonella Typhimurium from wood, tile or carpet to bologna (sausage) and bread.

METHODS AND RESULTS: Experiment 1. After 28 days, 1.5 to 2.5 log(10) CFU cm(-2) remained on tile from and the more concentrated media facilitated the survival of S. Typhimurium compared with the more dilute solutions. Experiments 2 and 3. The bacterial transfer rate to food decreased as the bacterial residence time on the surface increased from 2, 4, 8 to 24 h with transfers of 6.5, 4.8, 4.6 and 3.9 log CFU ml(-1) in the rinse solutions, respectively. Over 99% of bacterial cells were transferred from the tile to the bologna after 5 s of bologna exposure to tile. Transfer from carpet to bologna was very low (<0.5%) when compared with the transfer from wood and tile (5-68%).

CONCLUSIONS: (i) Salmonella Typhimurium can survive for up to 4 weeks on dry surfaces in high-enough populations to be transferred to foods and (ii) S. Typhimurium can be transferred to the foods tested almost immediately on contact.

SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the ability of bacteria to survive and cross-contaminate other foods even after long periods of time on dry surfaces, thus reinforcing the importance of sanitation on food contact to minimize the risk of foodborne illness.”

via scicurious

Photo: flickr/Sebastian Anthony

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CATEGORIZED UNDER: eat me, NCBI ROFL, told you so
  • Cath the Canberra Cook

    What happened in our evolution to make humans into such precious delicate little flowers that we can’t eat off the floor? I’ve been throwing raw meat scraps onto the floor for my cat to eat for more that eight years, and he’s still not dead.

  • Cathy

    But what is the probability that my floor has a high-enough concentration of salmonella in the first place?

  • Vonce

    Salmonella enterica subsp. enterica serovar Typhimurium (subsp and serovar being not in italics) is the correct nomenclature. Since Le Minor et als. 1982 and 1986 the nomenclature moved away from the traditional genus species. Note that Salmonella Typhimurium is commonly used to abbreviate the complete name and that the nomenclature is still in turmoil and ever evolving.

    J.P. Euzéby has a ”comprehensive” explanation of the Salmonella nomenclature battle. In all, its hell and no one has the right or wrong answer.

    Sorry I’m a microbiologist.

  • Matt B.

    This sentence is confusing: “Over 99% of bacterial cells were transferred from the tile to the bologna after 5 s of bologna exposure to tile.”
    I think they mean “before”, rather than “after”, i.e. it takes less than 5 seconds for 99% of the bacterial transfer to occur. One of those ambiguities of English; they’re using “after” to mean “over the course of”, but that would be clearer if they used “had been transferred” instead of “were transferred”.


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