Microorganisms belonging to the genus enterococcus in foods: Antibiotic resistance and opportunistic pathogenicity

Bacteria of the genus Enterococcus, or enterococci (formerly the "faecal" or Lancefield group D streptococci) are ubiquitous microorganisms. Enterococci are predominant inhabitants of the gastrointestinal tract of humans and animals and also commonly occur in large numbers in vegetables, plant material, and foods, especially those of animal origin such as dairy products. Although enterococci share a number of useful biotechnological traits (e.g. bacteriocin production, probiotic characteristics), there is no consensus on the significance of their presence in foodstuffs. The potential pathogenicity of enterococci in human clinical infections and their association with endocarditis have recently become a matter of controversy, in spite of the fact that foods containing enterococci have a long history of safe use. The importance of the enterococci for food and public health microbiologists is related to their enteric habitat, their entering the food chain, their antibiotic resistance, and their possible involvement in food-borne illnesses due to the presence of virulence factors, such as production of adhesins and aggregation substances. More detailed studies are still needed to comprehend the epidemiology, the ecological role, and the virulence of enterococci in foods.