D. E. Cosby

Distribution of Campylobacter spp. in selected U.S. poultry production and processing operations.

A study was conducted of 32 broiler flocks on eight different farms, belonging to four major U.S. producers. The farms were studied over I complete calendar year. Overall, 28 (87.5%) of the flocks became Campylobacter positive, and only four (12.5%) remained negative throughout the 6- to 8-week rearing period. In the majority of flocks, sampled every 2 weeks throughout production, Campylobacter-positive fecal and cecal samples were not detected until 4 to 8 weeks of age. In only six of the flocks were environmental samples found to be positive before shedding of Campylobacter was detected in the birds. Even in some of the Campylobacter-negative flocks, contamination of the rearing environment was positive for Campylobacter but did not result in the birds subsequently excreting the organism. These findings are discussed in relation to U.S. husbandry practices and present uncertainty about sources of Campylobacter infection for poultry flocks. Birds were often transported to the processing plant in coops that were already contaminated with Campylobacter, and the organisms were sometimes found in samples of scald water and chill water. After chilling, the proportions of Campylobacter-positive carcasses from different producers ranged from 21.0 to 40.9%, which is lower than in other studies, and possible reasons are considered.

Sources and movement of Salmonella through integrated poultry operations: a multistate epidemiological investigation.

The prevalence of Salmonella from numerous sources in 32 integrated broiler operations of high- and low-performing broiler houses was characterized from four states across four seasons. Previous studies of Salmonella in broilers have been limited in scope, offering only a snapshot of pathogen prevalence as seen on a small number of individual farms. Twenty-six different sample types were collected from the hatchery to the end of processing, and Salmonella was found in all sample types. A total of 10,740 samples were analyzed for Salmonella, and 973 (9.1%) of these samples, including 49 of 798 (6.1%) carcass rinse samples, were Salmonella positive. Hatchery transport pads (389 of 765, 50.8%), flies (28 of 150, 18.7%), drag swabs (57 of 402, 14.2%), and boot swabs (20 of 167, 12%) were samples from which Salmonella was most frequently isolated. Thirty-six different serotypes were identified, and the most frequently encountered serotypes were Salmonella Senftenberg, Salmonella Thompson, and Salmonella Montevideo. Determining critical contaminating sources and following the movement of Salmonella through integrated poultry operations will help researchers and the industry develop practical intervention strategies.

Movement and Persistence of Salmonella in Broiler Chickens following Oral or Intracloacal Inoculation

The dissemination of Salmonella into various lymphoid-like organs in young broiler chicks after oral and intracloacal inoculation was studied. A three-strain cocktail of Salmonella Typhimurium, Salmonella Montevideo, and Salmonella Enteritidis was administered either orally or intracloacally to day-old chicks. After 1 h, 1 day, or 1 week, the ceca, thymus, liver and gallbladder, spleen, and bursa were sampled for the presence of Salmonella. There was a marked difference in the recovery of Salmonella 1 h postinoculation. Only 6 of 50 samples from orally inoculated chicks were positive compared with 33 of 50 samples from cloacally inoculated samples. In comparison, 24 h and 1 week after inoculation, there was no difference in the number of positive samples between oral or cloacal inoculation. The rapidity of the translocation of the Salmonella from the cloacal inoculum compared to the oral inoculum is likely due to the transient time required for Salmonella to move through the alimentary tract. The method of inoculation did not affect the distribution of serogroups. Of the three serotypes in the composite inoculum, the Salmonella Enteritidis (group D) was recovered only twice in replication 1 and not at all in replication 2. Both the Salmonella Typhimurium (serogroup B) and the Salmonella Montevideo (serogroup C1) were recovered extensively throughout the study.

Sampling naturally contaminated broiler carcasses for Salmonella by three different methods.

Postchill neck skin maceration (NSM) and whole-carcass rinsing (WCR) are frequently used methods to detect salmonellae from processed broilers. These are practical, nondestructive methods, but they are insensitive and may result in false negatives (20 to 40%). Neck skin samples comprise only 4% of the skin from the broiler carcass by weight, while WCR will not detect firmly attached Salmonella organisms and only 7.5% of the rinsate is utilized. Whole-carcass enrichment (WCE) involves incubation of the whole carcass overnight in a preenrichment broth and can recover as few as 8 inoculated Salmonella cells per carcass. The objective of this study was to use NSM, WCR, and WCE sampling to detect naturally occurring Salmonella from the same commercially processed broiler either prechill or postchill. Ten carcasses were obtained prechill and another 10 postchill on each of two replicate days from each of two commercial processing plants. From each carcass, 8.3 g of neck skin was sampled, and then the carcass was rinsed with 400 ml of 1% buffered peptone water. Thirty milliliters was removed and incubated (WCR), and the remaining 370 ml of broth and the carcass were incubated at 37°C for 24 h (WCE). Overall, Salmonella organisms were detected on 21, 24, and 32 of 40 prechill carcasses by NSM, WCR, and WCE, respectively, while 2, 2, and 19 of 40 postchill carcasses were positive by the respective methods. Prechill carcasses were 64% (77 of 120) positive for Salmonella, while postchill carcasses were 19% (23 of 120) positive. Commercial processing reduced the positive-sample prevalence by 45%. Salmonella organisms were detected on 20% (24 of 120) of the samples from plant 1 and 63% (76 of 120) of the carcasses from plant 2. This study demonstrates significant differences in the results for Salmonella prevalence among sampling methods both before and after immersion chilling, as well as between processing plants on days that samples were taken.

Effect of dietary bacteriophage supplementation on internal organs, fecal excretion, and ileal immune response in laying hens challenged by Salmonella Enteritidis

ABSTRACT With the current researches on replacing antibiotics with different dietary interventions, bacteriophages (BP) are potential antimicrobial intervention because of their ability to affect specific bacteria. A study was conducted to evaluate the role of BP against Salmonella enterica serovar Enteritidis (SE) on SE internal organs colonization and ileum immune response in laying hens. Hens were challenged both orally and intracloacally with 108 cfu/mL cells of nalidixic acid resistant Salmonella Enteritidis (SENAR). Thirty‐two Single Comb White Leghorns were randomly allocated to 4 dietary treatments: 1) unchallenged control (negative control; T1), 2) SENAR challenged control (positive control; T2), 3) SENAR challenged + 0.1% BP (T3), and 4) SENAR challenged + 0.2% BP (T4). The number of SENAR in the ceca was significantly reduced by 0.2% BP supplementation (P < 0.05) at 7 d post infection (dpi). The respective number of SENAR was reduced from 2.9 log cfu/gm in T2 and T3 to 2.0 log cfu/gm in T4. There was no significant effect of T3 on reduction of numbers of cecal SENAR. A significant reduction of SENAR was observed in the liver with gall bladder (LGB) from 0.75 in T2 to 0.18 log cfu/gm in T4. In the spleen, T4 significantly reduced (P < 0.05) SENAR to 0.56 log cfu/gm compared to T2 and T3 (0.94 log cfu/gm). There was no significant effect of T3 in reduction of prevalence of spleen SENAR. By supplementing 0.2% BP (T4), the SENAR in the ovary was reduced to 0 log cfu/gm. There was a significant reduction (P < 0.05) in fecal SENAR at 6 dpi by T4 (0.71 log cfu/gm) compared to the positive control (1.57 log cfu/gm). The expression of interferon (IFN)‐Γ, interleukin (IL)‐6, and IL‐10 was significantly increased in the ileum by SENAR challenge compared to the negative control. This study suggests that apart from commonly used prebiotics or probiotics, BP are pathogen‐specific and can be used as one of the dietary strategies to reduce SE colonization and induce immune modulation in laying hens.

Bacterial Isolates from the Chicken Gizzard and Ceca with In Vitro Inhibitory Activity against Salmonella typhimurium

Bacterial isolates (197) obtained from the gizzard and ceca of 20 broiler and 40 specific-pathogen-free chickens, 21 days to 8 months of age, were evaluated for inhibitory activity against Salmonella typhimurium . One-hundred forty strains were characterized as gram negative and oxidase negative, typical of the Enterobacteriaceae . Five of the gram-negative and oxidase-negative isolates demonstrated inhibitory activity against six strains of S. typhimurium after 10- and 20-fold concentration and ammonium sulfate precipitation of the cell-free supernatant fluid from a culture grown in M9 minimal medium. Three isolates were identified as lactobacilli, 40 other strains exhibited Gram stain, oxidase, and catalase reactions typical of the Lactobacillus spp., and three known lactobacilli were included in the evaluation. Limited inhibitory activity was exhibited by these 46 isolates when tested against six S. typhimurium strains. Fourteen other strains not characterized as presumptive enterobacteria or lactic acid bacteria demonstrated little or no inhibitory activity against the six test strains.

Impact of desiccation and heat exposure stress on Salmonella tolerance to acidic conditions

ABSTRACT In a recent study, the pH of commonly used Salmonella pre-enrichment media became acidic (pH 4.0 to 5.0) when feed or feed ingredients were incubated for 24 h. Acidic conditions have been reported to injure or kill Salmonella. In this study, cultures of four known feed isolates (S. montevideo, S. senftenberg, S. tennessee, and S. schwarzengrund) and four important processing plant isolates (S. typhimurium, S. enteritidis, S. infantis, and S. heidelberg) were grown on meat and bone meal and later subjected to desiccation and heat exposure to stress the microorganism. The impact of stress on the isolates ability to survive in acidic conditions ranging from pH 4.0 to 7.0 was compared to the non-stressed isolate. Cell injury was determined on xylose lysine tergitol 4 (XLT4) and cell death determined on nutrient agar (NA). When measured by cell death in non-stressed Salmonella, S. typhimurium was the most acid tolerant and S. heidelberg was the most acid sensitive whereas in stressed Salmonella, S. senftenberg was the most acid tolerant and S. tennessee was the most acid sensitive. The pH required to cause cell injury varied among isolates. With some isolates, the pH required for 50% cell death and 50% cell injury was similar. In other isolates, cell injury occurred at a more neutral pH. These findings suggest that the pH of pre-enrichment media may influence the recovery and bias the serotype of Salmonella recovered from feed during pre-enrichment.

Evaluation of encapsulated sodium butyrate on growth performance, energy digestibility, gut development, and Salmonella colonization in broilers

&NA; Two experiments were conducted to determine the effect of an encapsulated sodium butyrate (Na‐B) with targeted releasing times on broiler performance, energy digestibility, intestinal morphology, and ceca Salmonella colonization. In experiment 1, 3 different Na‐B products (CMA, CMP, and CMS) were evaluated following a challenge with a nalidixic acid‐resistant Salmonella typhimurium (STNAR). Cobb‐Cobb male birds were placed 8 per pen into 6 replicates for each treatment. Treatments included 6 Na‐B treatments (500 and 1,000 ppm of each product) plus 2 control (non‐challenged and challenged). Birds were orally gavaged with 0.1 mL of 107 cfu/mL STNAR on d 4. Ceca and ileal samples were collected on d 11. In experiment 2, CMA and CMP products were evaluated for a full grow‐out period without an external challenge. Cobb‐Cobb male birds were distributed among 45 floor pens with 24 birds per pen. Treatments included 4 product treatments (500 and 1,000 ppm of each product) plus one control. Feed intake and pen weight were obtained on d 14, 28, and 42. Experiment 1 showed that CMP at 1,000 ppm had the highest value for BW and BWG on d 4 (P = 0.07). Adding CMA and CMP at 500 ppm increased ileal digestibility energy (IDE) compared to the challenged control (P ≤ 0.05). The Salmonella recovery data indicated that the challenge had a significant but mild impact, since it did not affect the performance variables but did result in a significant increase in log10 cfu/g cecal material between the non‐challenged and challenged control (1.42 vs 3.72). Experiment 2 showed that both products improved the villus height in the duodenum on d 21 (P = 0.08) and IDE on d 42, relative to the control (P ≤ 0.05). This study demonstrates that Na‐B has the potential to improve growth in broilers at an early age. The beneficial effects on intestinal morphology and IDE are affected not only by dosage level, but also by the products releasing time.

Colonization of mature laying hens with Salmonella Enteritidis by oral or intracloacal inoculation

&NA; Evidence of Salmonella Enteritidis (SE) in internal organs of White Leghorns once they are inoculated via the oral (OR) or intracloacal (IC) route has not been consistently demonstrated. The aim of the current study was to evaluate OR or IC inoculation route of a nalidixic acid (Nal) resistant SE (SENAR) on the SE colonization of ceca and the invasion of internal organs in mature White Leghorns. Five experiments were conducted, and hens were inoculated with 108 colony‐forming units (cfu) of SENAR. Hens were euthanized at 7 and 14 d post inoculation (dpi), and the ceca, spleen, liver with gall bladder (L/GB), and ovaries were collected for bacteriological analyses. The recovery of SENAR in ceca was 100% at 7 dpi. Recovery from the ovaries was lower than the other organs for both routes of inoculation. The SE recovery of L/GB, spleen, and ovaries at 7 dpi was not different between the two routes. By 14 dpi, all organs approached negative, and the recovery rate was similar between OR and IC. Fecal shedding was 100% positive at 3 dpi and reduced to almost 0% by 14 dpi. Mature hens were colonized by SENAR with either OR or IC inoculation when using a larger volume and a higher cfu/mL (0.1 mL OR in experiment 1 vs. 1.0 mL OR and IC in the rest). SENAR showed some translocation into other organs, to a greater extent with IC. The colonization did not persist either in ceca or the internal organs at 14 dpi.

Effect of probiotics on fecal excretion, colonization in internal organs and immune gene expression in the ileum of laying hens challenged with Salmonella Enteritidis

ABSTRACT A study was conducted to evaluate the supplementation of probiotics on Salmonella colonization in the ceca and various internal organs as well as immune response in laying hens challenged with Salmonella enterica serovar Enteritidis (SE). Thirty‐two 46‐wk‐old White Leghorns (W‐36) were housed individually in wired laying cages under 16L:8D lighting schedule. Hens were challenged individually with nalidixic acid resistant Salmonella Enteritidis (SENAR) after which time they were grouped into four treatments: T1 = SENAR unchallenged control, T2 = SENAR challenged control, T3 = SENAR challenged + 0.05% probiotics (Lactobacillus plantarum), and T4 = SENAR challenged + 0.1% probiotics. All hens, including T1, were euthanized and sampled for the liver with gall bladder (L/GB), ileum, ovary, spleen, and ceca on 7‐days post‐infection (dpi). Fecal screening was performed on individual hens at both 3 and 6 dpi. No difference was detected between the treatments in cecal SENAR enumeration, and the mean log 10 cfu/gm of SENAR in the ceca was 3.7 for all three treatments. The prevalence of SENAR was lowest for ovary in all treatments and was highest in the spleen. However, there were no significant differences among the treatments in the internal organs. There was no significant difference in the fecal shedding among the treatments on either 3 or 6 dpi, with incidence of positive feces higher at 3 dpi compared to 6 dpi (100 vs. 70% to 80%). SENAR challenge resulted in significant upregulation (P < 0.05) of interleukin (IL)‐1&bgr;, 6, 10, interferon gamma (IFN‐&ggr;), and toll‐like receptor (TLR)‐4 mRNA expression. Highest level of probiotics resulted in a significant decrease in IFN‐&ggr; and elevation of IL‐6 and IL‐10 gene expression in the ileum. However, IL‐1B and TLR‐4 gene expression were not different from the SENAR challenge control. This study reveals that there was important regulation of immune genes by probiotics supplementation.