VIRULENCE MARKERS AND ANTIMICROBIAL SUSCEPTIBILITY OF ESCHERICHIA COLI STRAINS ISOLATED FROM HOME MADE MOZZARELLA CHEESE IN BRAZIL.

Patricia Cardoso (FCAV/UNESP); José Moacir Marin (FORP/USP)

Cheesemaking is a major industry worldwide, and much is still practiced on a relatively small scale with only basic hygienic practices. Mozzarella cheese, a typical Italian product which is also marketed worldwide, was originally made from water buffalo milk, but now, in many countries some similar products are made using bovine or mixed bovine and water buffalo milk, in Minas Gerais only bovine milk is used in the manufacturing of this cheese. Escherichia coli is a normal inhabitant of the intestinal tract of humans and warm blooded animals, and the presence of this bacteria in the food is considered a indicative of fecal contamination. The aim of the present study was to investigate the virulence markers and antimicrobial susceptibility of E. coli strains isolated from home made mozzarella cheese. A total of 59 raw milk cheese samples were taken at a local producer in the Jequitinhonha Valley (Northeast of Minas Gerais, Brazil). The 147 E. coli isolates were screened for the presence of Shiga toxin-producing (stx 1 and stx 2) and intimin (eae) genes. Sixteen (10.8%) strains were shown by PCR to harbor stx genes (all of them harbored the stx 1 gene), 13 of them also were eae positive. The STEC strains were also screened for resistance to 12 antimicrobial agents. Predominant resistance was to streptomycin (37.5%), tetracycline (37.5%), ampicillin (31.2%) and amikacin (31.2%). Multidrug resistance was found among 5 isolates (31.2%). Results obtained in this work reinforce the suggestion that mozzarella cheese may be a potential vehicle for transmission of pathogenic STEC to humans.