Transfer of generic Escherichia coli and attenuated Salmonella enterica Typhimurium from the soil to the surface of in-shell pecans during harvest.

During harvest pecan nuts are at risk of contamination with foodborne pathogens from extended contact with the ground. The objective of this study was to determine the potential transfer of Escherichia coli and Salmonella from the ground to in-shell pecans during the harvesting process. Plots (2 m2) were sprayed with 1 L of a rifampicin (rif) resistant strain of either E. coli TVS 353 or an attenuated Salmonella Typhimurium inoculum at a low (∼4 log CFU/ml), mid (∼6 log CFU/ml) or high (∼8 log CFU/ml) concentrations. The following day, nuts were mechanically harvested and samples from each plot were collected at 1 min, 4 h, and 24 h. Samples were enumerated for Salmonella and E. coli on tryptic soy agar supplemented with rif. The Salmonella levels in the soil from the inoculated plots were 2.0 ± 0.3, 4.1 ± 0.1, and 6.4 ± 0.2 log CFU/g for the low, mid, and high inocula, respectively. The E. coli levels in the soil from the inoculated plots were 1.5 ± 0.4, 3.7 ± 0.3, and 5.8 ± 0.1 log CFU/g for the low, mid, and high inocula, respectively. There was a significant difference in the average daily rainfall among the three trials. Trial 3 received 23.8 ± 9.2 cm, while trials 1 and 2 received much less (0.1 ± 0.1 0.0 ± 0.0 cm, respectively). Inoculation concentration and trial were significant (P<0.05) factors that influenced the transfer of E. coli and Salmonella to pecans. For the high inoculum treatment, bacterial transfer to pecans ranged from 0.7 ± 0.3 to 4.1 ± 0.2 for E. coli and 1.3 ± 0.7 to 4.3 ± 0.4 log CFU/g for Salmonella. For the medium inoculum treatment, transfer ranged from <0.3 to 1.5 ± 0.1 for E. coli and <0.3 to 1.9 ± 0.2 log CFU/g for Salmonella. For the low treatment, transfer ranged from <0.3 to 0.4 ± 0.2 and <0.3 to 0.5 ± 0.1 log CFU/g for E. coli and Salmonella, respectively. These results show the need for implementing agricultural practices that prevent potential transfer of foodborne pathogens onto the surface of in-shell pecans during harvest.

Effects of dietary yeast cell wall supplementation on growth performance, intestinal Campylobacter jejuni colonization, innate immune response, villus height, crypt depth, and slaughter characteristics of broiler chickens inoculated with Campylobacter jejuni at d 21.

A study was conducted to assess the effects of a dietary yeast cell wall (YCW) with and without a Campylobacter jejuni (CJ) challenge. A total of 2,240-day-old Ross 708 males were randomly assigned within 8 treatments with a 4 × 2 factorial design, with 4 diets (negative control, positive control, YCW constant dose (400 g/ton), and YCW step-down dose (800/400/200 g/ton in the starter/grower/finisher diets, respectively) and with and without d 21 CJ oral gavage challenge at 5.2 × 107 CFU/mL. At d 0, 14, 28, and 41 body weights and feed consumption were measured to determine performance. At d 14, 28, and 42, 8 jejunal and ileal histology samples per treatment were collected for villi morphology measurements. At d 22 and 28 (1- and 7-days postinoculation), 24 ileal tissue samples per treatment were collected for relative gene expression analysis. At d 42, 24 cecal content samples per treatment were collected for CJ enumeration. Finally, on d 44, 96 birds per treatment were processed to determine carcass yield and 16 carcass rinses per treatment were collected to determine CJ prevalence after processing. Diet or inoculation did not impact broiler performance (P > 0.05). Limited differences were observed in intestinal morphology, and villus height and crypt depth were different only in the ileum at d 42 (P = 0.0280 and P = 0.0162, respectively). At d 1 postinoculation, differences between treatments inoculated with CJ and PBS were observed in the expression of avian beta defensin 10 (AvBD10), interleukin 1ß (IL-1ß), and interleukin 10 (IL-10) (P < 0.05). At d 7 postinoculation, expression of AvBD10, IL-1ß, and IL-10 was similar among all treatments (P > 0.05). At d 42, all birds, regardless the inoculation, had similar levels of CJ recovered from cecal contents (P > 0.05). After processing, carcass yield and CJ prevalence postchilling was similar in all treatments (P > 0.05). Overall, under the conditions of this study, the addition of YCW during a CJ challenge did not have an impact in growth performance, innate immune response, cecal colonization, carcass yield, or CJ prevalence after processing.

Effects of Common Litter Management Practices on the Prevalence of Campylobacter jejuni in Broilers.

Campylobacter is an important foodborne pathogen and is naturally found in chickens. During broiler production, litter can become contaminated with Campylobacter when birds defecate, and this litter, in some countries, is typically reused for the next flock, potentially causing cross-contamination. The goal of this experiment was to observe if reusing contaminated litter could spread Campylobacter between flocks and to observe if common litter treatments could prevent this cross-contamination. To determine this, a flock of birds was inoculated with Campylobacter jejuni and allowed to naturally contaminate the litter for 42 days. After grow-out, birds were terminated, and litter was given five treatments: uninoculated fresh litter, untreated re-used litter, composted re-used litter, re-used litter treated with sodium bisulfate (45 kg/305 m2), and re-used litter composted and treated with sodium bisulfate (45 kg/305 m2). A second flock was placed on the litter, grown for 42 days, and tested for C. jejuni prevalence. Following inoculation of the first flock, high prevalence of C. jejuni was observed; however, after a 19-day down-time between flocks, no C. jejuni was detected in any samples from the second flock. These results indicate that re-used litter was not a significant reservoir for cross-contamination of broilers when provided a significant down-time between flocks.

A Comparison of Colonizing Ability Between Salmonella Enteritidis and Salmonella Heidelberg in Broiler Chickens Challenged Through Feed Administration.

With over 1 million estimated cases per year in the United States, foodborne salmonellosis is an important public health issue. Chicken products are frequent sources of foodborne Salmonella infection. These bacteria readily colonize the gastrointestinal tract of broiler chickens, and feed is a known vector. Past research has demonstrated that the survivability of Salmonella in feed is dependent on the serovar and strain. Therefore, the objective of this research was to compare colonization incidence of these two serovars in broiler chicken tissues by administration of feed contaminated with Salmonella enterica serovar Enteritidis (SE) or Salmonella enterica serovar Heidelberg (SH). A comparison was made with equal conditions so that there was no influence of other factors. Birds were inoculated by addition of Salmonella to the feed (1 × 104 colony-forming unit [CFU]/g of feed) at 14 days of age, and the following tissue samples were collected from each bird after grow-out (days 34-41 depending on the trial): abdominal cavity swab, bone marrow swab, cloaca swab, lung swab, breast, bursa and thymus, ceca, crop, kidney, liver and spleen, skin, spinal cord, thigh, and trachea. A higher percentage of birds inoculated with SE were positive in at least one tissue compared with SH (68% and 9%, respectively), and the SE inoculated birds also showed a higher number of positive tissue samples than SH (13.1% and 0.7%, respectively). Recovery of SH was low for all tissue samples. However, recovery of SE was variable between samples, with ceca showing the highest percentage (50%). These results indicate that challenge at day 14 through feed administration results in greater colonization by SE compared with SH, suggesting that monitoring and control methods for Salmonella in feed should focus on SE to have the greatest positive effect.