Tracing of Salmonella spp. in two pork slaughter and cutting plants using serotyping and macrorestriction genotyping

The possible origin of beef contamination and genetic diversity of Escherichia coli populations in beef cattle, on carcasses and ground beef, was examined by using random amplification of polymorphic DNA (RAPD) and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the fliC gene. E. coli was recovered from the feces of 10 beef cattle during pasture grazing and feedlot finishing and from hides, carcasses, and ground beef after slaughter. The 1,403 E. coli isolates (855 fecal, 320 hide, 153 carcass, and 75 ground beef) were grouped into 121 genetic subtypes by using the RAPD method. Some of the genetic subtypes in cattle feces were also recovered from hides, prechilled carcasses, chilled carcasses, and ground beef. E. coli genetic subtypes were shared among cattle at all sample times, but a number of transient types were unique to individual animals. The genetic diversity of the E. coli population changed over time within individual animals grazing on pasture and in the feedlot. Isolates from one animal (59 fecal, 30 hide, 19 carcass, and 12 ground beef) were characterized by the PCR-RFLP analysis of the fliC gene and were grouped into eight genotypes. There was good agreement between the results obtained with the RAPD and PCR-RFLP techniques. In conclusion, the E. coli contaminating meat can originate from cattle feces, and the E. coli population in beef cattle was highly diverse. Also, genetic subtypes can be shared among animals or can be unique to an animal, and they are constantly changing.

Section: Discussionmentioning

confidence: 99%

“…togenes, Campylobacter spp., and Salmonella spp. during pork and shrimp production processes (9,10,21,22). DNA profiling methods as well as standard bacteriological methods have also been used to establish a relationship between preslaughter E. coli O157 contamination in cattle and carcass contamination (3,7,11).…”

Section: Discussionmentioning

confidence: 99%

Origin of Contamination and Genetic Diversity of Escherichia coli in Beef Cattle

Aslam

Nattress

Greer

et al. 2003

“…Besides serotyping and phage typing, powerful bacterial molecular typing methods, such as plasmid profiling, pulsed-field gel electrophoresis (PFGE), IS200 typing, ribotyping, random amplified polymorphic DNA analysis, and amplified fragment length polymorphism, are used for epidemiological investigation of salmonellae (3,7,8,13,16). These techniques are useful for defining clonal relationships between strains (17) and for assessing the distribution of Salmonella strains within food-processing environments (10,15).…”

mentioning

confidence: 99%

Phenotypic and Molecular Typing of Salmonella Strains Reveals Different Contamination Sources in Two Commercial Pig Slaughterhouses

Botteldoorn¹,

Herman²,

Rijpens³

et al. 2004

This study aimed to define the origin of Salmonella contamination on swine carcasses and the distribution of Salmonella serotypes in two commercial slaughterhouses during normal activity. Salmonellae were isolated from carcasses, from colons and mesenteric lymph nodes of individual pigs, and from the slaughterhouse environment. All strains were serotyped; Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Derby isolates were additionally typed beyond the serotype level by pulsed-field gel electrophoresis (PFGE) and antibiotic resistance profiling (ARP); and a subset of 31 serotype Typhimurium strains were additionally phage typed. PFGE and ARP had the same discriminative possibility. Phage typing in combination with PFGE could give extra information for some strains. In one slaughterhouse, 21% of the carcasses were contaminated, reflecting a correlation with the delivery of infected pigs. Carcass contamination did not result only from infection of the corresponding pig; only 25% of the positive carcasses were contaminated with the same serotype or genotype found in the corresponding feces or mesenteric lymph nodes. In the other slaughterhouse, 70% of the carcasses were contaminated, and only in 4% was the same genotype or serotype detected as in the feces of the corresponding pigs. The other positive carcasses in both slaughterhouses were contaminated by genotypes present in the feces or lymph nodes of pigs slaughtered earlier that day or from dispersed sources in the environment. In slaughterhouses, complex contamination cycles may be present, resulting in the isolation of many different genotypes circulating in the environment due to the supply of positive animals and in the contamination of carcasses, probably through aerosols.

“…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 flora comes into contact with the surfaces of equipment in the cutting halls (4,22,37). It can detach from the carcass and then contaminate sound products placed on the equipment.…”

mentioning

confidence: 99%

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

Midelet

Carpentier

2002

165

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...