title: Prevalence and characterization of Listeria monocytogenes, Salmonella and Shiga toxin-producing Escherichia coli isolated from small Mexican retail markets of queso fresco.
abstract: Queso fresco (QF) is a handmade cheese consumed and produced in Latin America. In Mexico, QF production is associated with a microbiological risk. The aim of the study was to determine the incidence and characterization of Listeria monocytogenes, Salmonella spp., and Shiga toxin-producing Escherichia coli (STEC) in QF from retail markets of the north-western State of Sinaloa, Mexico, and to assess the effect of physicochemical parameters on Listeria presence. A total of 75 QF samples were obtained. L. monocytogenes, E. coli, and coliforms were detected in 9.3, 94, and 100%, respectively. Salmonella was not detected. STEC isolates showed virulence genes. Microbial loads were above the maximum values recommended by the Official Mexican Standards. Physicochemical parameters such as water activity (aw), moisture content, pH, and salinity played a role in Listeria prevalence in QF. Rigorous control in QF made in Culiacan, Mexico is needed to reduce the risk of foodborne pathogens.
authors.affiliation: a Department of Soil, Water and Environmental Science , University of Arizona , Tucson , AZ , USA.
authors.forename: Marcela
authors.initials: M
authors.lastname: Soto Beltran
authors.forename: Charles P
authors.initials: CP
authors.lastname: Gerba
authors.forename: Anna
authors.initials: A
authors.lastname: Porto Fett
authors.forename: John B
authors.initials: JB
authors.lastname: Luchansky
authors.forename: Cristobal
authors.initials: C
authors.lastname: Chaidez
mesh_terms: D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008800:Mexico; D016133:Polymerase Chain Reaction; D012475:Salmonella / Q000302:isolation & purification*; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification*
keywords: Escherichia coli; Listeria monocytogenes; Salmonella; Shiga toxin; food safety; queso fresco