Transfer of Microorganisms, Including Listeria monocytogenes , from Various Materials to Beef

Abstract

The quantity of microorganisms that may be transferred to a food that comes into contact with a contaminated surface depends on the density of microorganisms on the surface and on the attachment strengths of the microorganisms on the materials. We made repeated contacts between pieces of meat and various surfaces (stainless steel and conveyor belt materials [polyvinyl chloride and polyurethane]), which were conditioned with meat exudate and then were contaminated with Listeria monocytogenes, Staphylococcus sciuri, Pseudomonas putida, or Comamonas sp. Attachment strengths were assessed by the slopes of the two-phase curves obtained by plotting the logarithm of the number of microorganisms transferred against the order number of the contact. These curves were also used to estimate the microbial population on the surface by using the equation of A. Veulemans, E. Jacqmain, and D. Jacqmain (Rev. Ferment. Ind. Aliment. 25:58-65, 1970). The biofilms were characterized according to their physicochemical surface properties and structures. Their exopolysaccharide-producing capacities were assessed from biofilms grown on polystyrene. The L. monocytogenes biofilms attached more strongly to polymers than did the other strains, and attachment strength proved to be weaker on stainless steel than on the two polymers. However, in most cases, it was the population of the biofilms that had the strongest influence on the total number of CFU detached. Although attachment strengths were weaker on stainless steel, this material, carrying a smaller population of bacteria, had a weaker contaminating capacity. In most cases the equation of Veulemans et al. revealed more bacteria than did swabbing the biofilms, and it provided a better assessment of the contaminating potential of the polymeric materials studied here.When bacteria attach to surfaces and colonize them, their phenotypes change. They show, for instance, a decreased susceptibility to disinfectant (41, 42) and an increased exopolysaccharide production (46), and the community they form is called a biofilm. Biofilms are an integral part of our environment. In some cases they can be used in bioreactors to process waste; in other cases they cause malfunctions of one kind or another. The formation of biofilms creates major problems in such activities as water distribution (biofilms form in the distribution networks) (2, 10), health care (11, 13), and the food industry (7,8,14). A study by Haeghebaert et al. (24) has suggested that 40.5% of all food-borne infection outbreaks registered in France in 1996 were linked to contamination by equipment, highlighting the hazard that biofilms represent. In this study we examined biofilms liable to cause problems in the meat industry. Many studies have shown that when animals are slaughtered, microbial flora remains on the surface of the carcasses (5, 21), and despite the decontamination processes carried out (scorching the skin or using hot water, organic acid, or phosphate solutions), part of the microflora survives (3, 52). This resident fl...

Disinfection Treatment of Heated Scallop-Shell Powder on Biofilm of <i>Escherichia coli</i> ATCC 25922 Surrogated for <i>E. coli</i> O157:H7

“…Biofilms are more resistant to environmental stresses such as nutritional and oxidative stresses, desiccation, UV light exposure, and sanitizing agents, than free microorganisms [2]. Biofilms attached to food contact surfaces such as stainless steel, polyvinyl chloride and polyurethane are a continuous source of food spoilage bacteria and pathogens in food processing environments [3][4][5][6]. Among the biofilm-forming species is the enterohemorrhagic strain Escherichia coli O157:H7 [7].…”

Construction and Analysis of Fractional Multifactorial Designs To Study Attachment Strength and Transfer of Listeria monocytogenes from Pure or Mixed Biofilms after Contact with a Solid Model Food

“…We have previously demonstrated the influence of three factors: substrate material, bacterial species, and prior contact with a sanitizer (34,35). Previously, we demonstrated that in pure culture L. monocytogenes adhered more strongly to polychloride vinyl or polyurethane conveyor belt materials than three other non-Listeria bacterial strains of food industry origin (35).…”

Flagellin fromListeria monocytogenesIs Glycosylated with β-O-LinkedN-Acetylglucosamine

“…Listeria species are found throughout the food-processing environment (9,17,28,36) and can survive adverse conditions such as high salt levels and both pH (32) and temperature (48) extremes. However, the organism does not survive thermal processing; contamination of food generally results from contact of a processed food with a spoiled surface prior to packaging (27) or through the use of contaminated ingredients in minimally processed foods. Postprocessing contamination remains an important issue, since L. monocytogenes can proliferate within a contaminated food product at refrigeration temperatures (27,48).…”