Inhibition and reversal of Salmonella typhimurium attachment to poultry skin using zinc chloride

Influence of Zinc Sulphate on the Probiotic Properties of Lactobacillus plantarum CCM 7102

The effects of zinc sulphate on selected properties of L. plantarum CCM 7102 were tested in vitro. The resistance of lactobacilli to higher concentrations of ZnSO4 (up to 5000 mg Zn2+.l−1) in growth media was strain-dependent. Further studies were carried out on the most resistant strain of L. plantarum CCM 7102. While the addition of low concentrations of zinc sulphate into the growth media (< 100 mg Zn2+.l−1) did not influence the properties of L. plantarum CCM 7102, the concentrations of 100—500 mg Zn2+.l−1 stimulated: the growth rate, production of lactic acid, adhesion to porcine enterocytes and the inhibition of pathogens E. coli O8:K88+ent+, S. enterica and S. Typhimurium. Conversely, however, high concentrations > 500 mg Zn2+.l−1 inhibited these properties. The addition of zinc (250 mg Zn2+.l−1) did not affect the resistance to antimicrobials, low pH, and the resistance to bile salt was affected only weakly. Zinc-resistant probiotic Lactobacillus strains are suitable for use in feedstuffs with a higher content of zinc designed for the prevention of post weaning diarrhoea in pigs.

Quantification of loosely associated and tightly associated bacteria on broiler carcass skin using swabbing, stomaching, and grinding methods

This research was conducted to quantify bacterial populations after swabbing or stomaching, followed by grinding the swabbed or stomached broiler skins. For each of 3 replications, 3 eviscerated broilers were randomly taken from a processing line in a local broiler processing plant. Ten swabs and 10 stomachs per bird were conducted on the left- and the right-side skins (10×7 cm), respectively, which were then finally ground. Results indicated that mesophilic aerobic bacteria (MAB) in the first swabbed sample were significantly lower than those in the first stomached sample (P<0.05), with no difference seen for the remaining sampling times (P>0.05). During 10 swabbings followed by final grinding, 8, 9, and 83% of MAB were detected after the first swabbing, after the second through 10th swabbings, and after final grinding of the skin, respectively. During 10 stomachings followed by the final grinding, 17, 18, and 65% of MAB were detected after the first stomaching, after the second through 10th stomachings, and after final grinding of the skin, respectively. Escherichia coli (E. coli) and coliforms were significantly higher in the first stomaching than those in the first swabbing (P<0.05), with no difference seen between the 2 sampling methods for the rest sampling times (P>0.05). Populations of E. coli and coliforms decreased step-wisely from the highest after grinding to the intermediate after first and second sampling, and to the least after 10th sampling (P<0.05), regardless of swabbing or grinding. In this study, less than 35% of MAB seemed loosely associated in the skin of eviscerated broiler, whereas more than 65% of MAB looked tightly associated, which were not recovered by stomaching or swabbing even 10 times but were recovered by grinding the skin.

Attachment strength to pork skin and resistance to quaternary ammonium salt and heat of Escherichia coli isolates recovered from a pork slaughter line

The aim of this study was to determine whether the attachment strength to pork skin, quaternary ammonium salt resistance, and thermal inactivation kinetics (at 65 degrees C) of a range of Escherichia coli isolates could be correlated with their temporal stability (persistence) within a pork slaughter line. The genetic lineage of the E. coli isolates was determined using enterobacterial repetitive intergenic consensus-PCR. The genotypes were divided into transient and endemic populations based on the number of times they were recovered within and across sampling visits made to a pork slaughterhouse. No significant variation in the D-value at 65 degrees C (0.27 to 0.51 min) was observed among the genotypes tested. However, differences in D-values were found for 100 ppm quaternary ammonium salt (3.0 to 6.0 min). All of the E. coli genotypes attached strongly to pork skin, and a high proportion of cells were irreversibly bound (39 to 42% of the initial inoculum). However, variation among genotypes was found with respect to loose attachment (21 to 33% of inoculated cells). No correlation between persistence of E. coli genotypes within the slaughter line and attachment strength or quaternary ammonium salt resistance was found. Variation in either physiological attribute could not be predicted based on genetic lineage. Additional or alternative factors may contribute to the ability of E. coli populations to become endemic within pork processing facilities. More studies should be conducted to elucidate the underlying factors that promote the formation of endemic populations of E. coli and other enteric bacteria (e.g., Salmonella) within slaughter lines.

The combination of zinc compounds and acidic pH limits aerobic growth of a Salmonella typhimurium poultry marker strain in rich and minimal media

The objective of the present study was to examine the combined effects of zinc compounds with different acidic pH levels on the aerobic growth of a S. typhimurium poultry isolate in either rich or minimal media. When overall main effects of pH levels of medium or concentrations of Zn compounds were compared, growth rates of the S. typhimurium poultry isolate were significantly (p < 0.05) decreased by stepwise increase of pH levels of medium (pH 4, 5, 6, and 7) or concentrations (0.67, 3.35, and 6.03%) of Zn compounds (Zn acetate and Zn sulfate). In general growth rates of S. typhimurium poultry isolate appeared to be more reduced by Zn acetate than by Zn sulfate and more reduced in minimal media compared to rich media.