Dissemination of Enterococcus faecalis and Enterococcus faecium in a Ricotta Processing Plant and Evaluation of Pathogenic and Antibiotic Resistance Profiles

• Published in: Journal of food science Vol. 80; no. 4; pp. M765 - M775
• Main Authors: Fernandes, Meg da Silva, Fujimoto, Graciela, de Souza, Leandro Pio, Kabuki, Dirce Yorika, da Silva, Márcio José, Kuaye, Arnaldo Yoshiteru
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.04.2015; Wiley Subscription Services, Inc
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Bacteriology; Contamination; Cylas; Dairy Products - microbiology; DNA, Intergenic; Drug resistance; Drug Resistance, Microbial - genetics; E. faecalis; E. faecium; Enterococcus; Enterococcus faecalis; Enterococcus faecalis - growth & development; Enterococcus faecalis - isolation & purification; Enterococcus faecalis - pathogenicity; Enterococcus faecium; Enterococcus faecium - growth & development; Enterococcus faecium - isolation & purification; Enterococcus faecium - pathogenicity; Food Microbiology; Food science; Gene expression; Genes; Genes, Bacterial; Humans; ITS region; Polymerase Chain Reaction; Raw materials; ricotta; Sequencing; Similarity; Virulence; Virulence Factors - genetics; ITS region; ricotta; E. faecium; E. faecalis; sequencing
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/1750-3841.12824

In this work, the sources of contamination by Enterococcus spp. in a ricotta processing line were evaluated. The isolated strains were tested for virulence genes (gelE, cylA,B, M, esp, agg, ace, efaA, vanB), expression of virulence factors (hemolysin and gelatinase), and the resistance to 10 different antibiotics. Enterococcus faecium and Enterococcus faecalis were subjected to discriminatory identification by intergenic spacer region (ITS)‐polymerase chain reaction and sequencing of the ITS region. The results showed that Enterococcus spp. was detected in the raw materials, environment samples and the final product. None of the 107 Enterococcus isolates were completely free from all virulence genes considered. A fraction of 21.5% of the isolates containing all of the genes of the cylA, B, M operon also expressed β‐hemolysis. Most of the isolates showed the gelE gene, but only 9.3% were able to hydrolyze gelatin. In addition, 23.5% of the observed Enterococcus isolates had the vanB gene but were susceptible to vancomycin in vitro. The dissemination of antibiotic‐resistant enterococci was revealed in this study: 19.3% of the E. faecium samples and 78.0% of the E. faecalis samples were resistant to at least one of the antibiotics tested. Sequencing of region discriminated 5 and 7 distinct groups among E. faecalis and E. faecium, respectively. Although some similarity was observed among some of the isolates, all E. faecalis and E. faecium isolates had genetic differences both in the ITS region and in the virulence profile, which makes them different from each other. Practical Application Enterococcus spp. were found in raw materials, processing environment and ricotta. Mold was considered the major font of contamination in the processing ricotta line. The expression of hemolytic activity was greater for Enterococcus faecium isolates, while the expression of gelatinase and antibiotic resistance was greater for Enterococcus faecalis. Sequencing showed a wide diversity in the isolates of E. faecalis and E. faecium.