Occurrence of non-O157 Shiga toxin-encoding Escherichia coli in artisanal mozzarella cheese in Brazil: risk factor associated with food workers

Abstract

Mozzarella cheese is considered a safe food due to the high temperature treatment used in the traditional process of stretching into hot water; however, a post-process contamination during the cheese manufacture or during the processing (before distribution) could occur. This study investigated the occurrence of Shiga toxin-encoding Escherichia coli (STEC) strains in homemade-mozzarella cheese. In total, 59 raw milk cheese samples collected at a local producer in the Jequitinhonha Valley (Northeast of Minas Gerais, Brazil) were submitted for microbiological analysis, and 38 (64.4%) tested positive for E. coli. Then, 147 strains of E. coli were isolated from positive samples and screened by polymerase chain reaction for the presence of the genes encoding the following virulence factors: stx1 and stx 2 (verotoxin types 1 and 2) and eae (intimin). All the isolates were negative for the stx 2, 14 isolates (9.5%) were positive for the stx1 gene, and 11 of them also harbored the eae gene. A food worker was probably involved in cheese contamination during the manufacture schedule. While the development of STEC infection in humans is not completely understood, all STEC-contaminated food can be considered potentially hazardous.Keywords: Escherichia coli; virulence genes; homemade cheese; food handler contamination.Practical Application: This study demonstrates that mozzarella cheese may be a vehicle for STEC non-D157 strain dissemination among humans, which is a reason for concern due to the high consumption of this cheese by the Brazilian population.

Shiga toxin‐producingEscherichia coliin the animal reservoir and food in Brazil

“…In this context, there were no reports of STEC from pasteurized milk (Hoffmann et al ; Silva et al ) and pasteurized milk cheese samples in Brazil (Martins et al ; Okura and Marin ). In contrast, the percentage of raw milk and raw milk cheese samples contaminated by STEC ranged from 3.3 to 65% (Vicente et al ; Silva et al ) and 6·0 to 23·3% (Paneto et al ; Cardoso and Marin ) respectively (Table ).…”

“…In addition, raw milk (Vicente et al ; Sandrini et al . ), pasteurized milk (Hoffmann et al ; Silva et al ), cheese (Paneto et al ; Martins et al ; Cardoso and Marin ), chicken (Gonzalez et al ), fish (Ribeiro et al ; Cardozo et al ) and water (Vicente et al ; Sandrini et al . ; Lascowski et al ) have also been investigated (Table ).…”

Raw milk cheese as a potential infection source of pathogenic and toxigenic food born pathogens

“…Also, it has been shown that coagulase negative staphylococcus (CNS) may be involved in food poisoning because they can also carry enterotoxin encoding genes (se genes) in their genomes that they are thermoresistant (Samelis et al, 2019). The Staphylococcus spp enterotoxin (SE) genes are encoded in mobile genetic elements, such as plasmids, prophages, and pathogenic islands that are able to be transmitted though S. aureus strains even during food processing (Cardoso & Marin, 2017). The Shiga toxin-producing E. coli (STEC) is characterized as a group of highly pathogenic strains that produce one or more Shiga toxins that can cause infections ranging from/uncomplicated diarrhea to severe diseases as hemorrhagic colitis and life-threatening hemolytic uremic syndrome (HUS).…”

“…Nevertheless, the safety of raw milk cheese has been questioned due to its relation to large outbreaks of foodborne been reported (Cardoso & Marin, 2017), especially when considered that Shiga toxin-producing E. coli strains have been detected before Cardoso & Marin, 2017). To better determinate contamination and safety of raw milk cheese a characterization of E. coli strains and of S. aureus were evaluated in Raw milk cheese from various market to at Jaboticabal, Sao Paulo state and at Aracaju, Sergipe, Brazil.…”

Brazilian Artisanal Cheeses: An Overview of their Characteristics, Main Types and Regulatory Aspects

“…The cheese market in Brazil is characterized by the existence of a large number of small cheese makers, with nearly 40% categorized as artisanal cheeses (SEBRAE, ). Artisanal cheeses are typically characterized by production in small scale, using milk produced on the farm and following traditional cheese‐making techniques proper from each region (Cardoso & Marin, ; Kamimura, De Filippis, Sant'Ana, & Ercolini, ; Martins et al., ).…”