Survival of Shiga toxin-producing Escherichia coli O157:H7 in Minas frescal cheese

Jesieli Braz Frozi, Josiane Roberto Domingues, Luciana Maria Ramires Esper, Joel Maurício Corrêa da Rosa, Ana Luiza Sant’Anna da Costa Silva, Alice Gonçalves Martins Gonzalez

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Shiga toxin-producing Escherichia coli (STEC) O157:H7 strains (isolated by cattle’s faeces and a reference strain, EDL933), were inoculated into pasteurized milk (102 and 103 cells.mL–1) to prepare the Minas frescal cheese. As control was used uninfected milk. Physicochemical and microbiological analyses were performed to milk and elaborated cheese. The O157:H7 strains were quantified in the stages of cheese processing and during 0, 2, 4, 5, 7, 10 and 15 storage days at 8 °C onto Sorbitol MacConkey Agar supplemented with potassium tellurite and cefixime (CT-SMAC). O157:H7 was not present in the pasteurised milk prior to the artificial inoculation. At the end of the processing the cheese had 10 to 100 times more STEC O157:H7 than the initial inoculum. During the storage, the Minas frescal cheese exhibited the largest population increase on the 4th and 5th day when inoculated with 102 and 103 cells.mL–1, respectively. Additionally, viable cells were found up to the 10th and 15th day, according to the amount of initial inoculum. This number of cells is able to cause infection in humans, and therefore, Minas frescal cheese, even when stored under refrigeration, is a potential vehicle of disease caused by STEC O157:H7.

Original languageEnglish
Pages (from-to)108-114
Number of pages7
JournalFood Science and Technology (Brazil)
Volume35
Issue number1
DOIs
StatePublished - 2015
Externally publishedYes

Keywords

  • Cheese
  • Foodborne disease
  • Psychrotrophic bacteria

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