The impact of immunoglobulin in acute HIV infection on the HIV reservoir: a randomized controlled trial.

OBJECTIVES: Antiretroviral therapy (ART) during acute HIV infection (AHI) restricts the HIV reservoir, but additional interventions are necessary to induce a cure. Intravenous immunoglobulin (IVIG) is not HIV-specific but is safe and temporarily reduces the HIV reservoir in chronic HIV infection. We present a randomized controlled trial to investigate whether IVIG plus ART in AHI reduces the HIV reservoir and immune activation compared with ART alone. METHODS: Ten men with AHI (Fiebig II-IV) initiated ART (tenofovir, entricitabine, ritonavir boosted darunavir and raltegravir) at HIV-1 diagnosis and were randomized to ART alone or ART plus 5 days of IVIG, once virally suppressed (week 19). Blood samples were evaluated for viral reservoir, immune activation, immune exhaustion and microbial translocation. Flexible sigmoidoscopy was performed at weeks 19, 24 and 48, and gut proviral DNA and cell numbers determined. RESULTS: IVIG was well tolerated and no viral blips (> 50 HIV-1 RNA copies/mL) occurred during IVIG therapy. From baseline to week 48, total HIV DNA in peripheral blood mononuclear cells (PBMCs) (cases: -3.7 log10 copies/106 CD4 cells; controls: -3.87 log10 copies/106 CD4 cells) declined with no differences observed between the groups (P = 0.49). Declines were observed in both groups from week 19 to week 48 in total HIV DNA in PBMCs (P = 0.38), serum low copy RNA (P = 0.57) and gut total HIV DNA (P = 0.55), but again there were no significant differences between arms. Biomarkers of immune activation, immune exhaustion and microbial translocation and the CD4:CD8 ratio were similar between arms for all comparisons. CONCLUSIONS: Although safe, IVIG in AHI did not impact total HIV DNA, immune function or microbial translocation in peripheral blood or gut tissue.

Prevalence and Serogroup Diversity of Salmonella for Broiler Neck Skin, Whole Carcass Rinse, and Whole Carcass Enrichment Sampling Methodologies following Air or Immersion Chilling.

The purpose of this study was to evaluate neck skin (NS), whole carcass rinse (WCR), and whole carcass enrichment (WCE) sampling procedures for Salmonella isolation and serogroup identification from the same broiler chicken carcass treated with air or immersion chilling. Commercially processed and eviscerated broiler carcasses were collected from a commercial processing plant, individually bagged, and transported to the pilot processing plant. In experiment 1, carcasses were air chilled to 4°C. In experiment 2, carcasses were immersion chilled with or without chlorine. After air chilling, Salmonella was detected on 78% of NS and 89% of WCE samples. Only one Salmonella serogroup was detected from each of 13 Salmonella-positive NS samples, and two serogroups were detected on 1 Salmonella-positive NS sample. Only one Salmonella serogroup was detected from each of 13 Salmonella-positive WCE samples, and two serogroups were detected from 3 Salmonella-positive WCE samples. After immersion chilling without chlorine, Salmonella was detected on 38% of NS, 45% of WCR, and 100% of WCE samples. Without chlorine, the 15 Salmonella-positive NS samples included 14 samples with one serogroup and 1 sample with two serogroups. Only one Salmonella serogroup was detected from WCR samples after immersion chilling. Of 40 Salmonella-positive WCE samples, 23 had a one, 14 had two, and 3 had three Salmonella serogroups. After immersion chilling with chlorine, Salmonella was detected on 35% of NS, 0% of WCR, and 90% of WCE samples. With chlorine, the 14 Salmonella-positive NS samples included 11 samples with one serogroup and 3 samples with two serogroups. No Salmonella serogroups were detected from WCR samples after immersion chilling with 20 mg/liter free chlorine. The 36 Salmonella-positive WCE samples included 21 samples with one serogroup and 15 samples with two serogroups. NS and WCE sampling methodologies yielded similar prevalence and serogroup diversity after air chilling. However, after immersion chilling with or without chlorine, WCE sampling yielded significantly higher (α ≤ 0.05) prevalence and serogroup diversity than either NS or WCR sampling methodologies.

Optimizing buffering chemistry to maintain near neutral pH of broiler feed during pre-enrichment for Salmonella.

Salmonella is a human pathogen that can accompany live broilers to the slaughter plant, contaminating fully processed carcasses. Feed is one potential source of Salmonella to growing broilers. Monitoring feed for the presence of Salmonella is part of good agricultural practice. The first step in culturing feed for Salmonella (which may be at low numbers and sub-lethally stressed) is to add it to a pre-enrichment broth which is incubated for 24 h. During the course of pre-enrichment, extraneous bacteria metabolize carbohydrates in some feed and excrete acidic byproducts, causing the pH to drop dramatically. An acidic pre-enrichment pH can injure or kill Salmonella resulting in a failure to detect, even if it is present and available to infect chickens. The objective of this study was to test an array of buffering chemistries to prevent formation of an injurious acidic environment during pre-enrichment of feed in peptone water. Five grams of feed were added to 45 mL of peptone water buffered with carbonate, Tris pH 8, and phosphate buffering ingredients individually and in combination. Feed was subjected to a pre-enrichment at 35°C for 24 h; pH was measured at 0, 18, and 24 h. Standard phosphate buffering ingredients at concentrations up to 4 times the normal formulation were unable to fully prevent acidic conditions. Likewise, carbonate and Tris pH 8 were not fully effective. The combination of phosphate, carbonate, and Tris pH 8 was the most effective buffer tested. It is recommended that a highly buffered pre-enrichment broth be used to examine feed for the presence of Salmonella.

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.

Minimization of Salmonella contamination on raw poultry.

Many reviews have discussed Salmonella in poultry and suggested best practices to minimize this organism on raw poultry meat. Despite years of research and conscientious control efforts by industry and regulatory agencies, human salmonellosis rates have declined only modestly and Salmonella is still found on raw poultry. Expert committees have repeatedly emphasized the importance of controlling risk, but information about Salmonella in poultry is often limited to prevalence, with inadequate information about testing methods or strains of Salmonella that are detected by these methods and no information about any impact on the degree of risk. This review examines some assumptions behind the discussion of Salmonella in poultry: the relationships between sampling and cultural methodology, prevalence and numbers of cells, and the implications of serotype and subtype issues. Minimizing Salmonella contamination of poultry is not likely to reduce human salmonellosis acquired from exposure to contaminated chicken until these issues are confronted more systematically.

Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens.

These studies evaluated the bacterial level of unwashed and washed shell eggs from caged and cage-free laying hens. Hy-Line W-36 White and Hy-Line Brown laying hens were housed on all wire slats or all shavings floor systems. On the sampling days for experiments 1, 2, and 3, 20 eggs were collected from each pen for bacterial analyses. Ten of the eggs collected from each pen were washed for 1 min with a commercial egg-washing solution, whereas the remaining 10 eggs were unwashed before sampling the eggshell and shell membranes for aerobic bacteria and coliforms (experiment 1 only). In experiment 1, the aerobic plate counts (APC) of unwashed eggs produced in the shavings, slats, and caged-housing systems were 4.0, 3.6, and 3.1 log(10) cfu/mL of rinsate, respectively. Washing eggs significantly (P < 0.05) reduced APC by 1.6 log(10) cfu/mL and reduced the prevalence of coliforms by 12%. In experiment 2, unwashed eggs produced by hens in triple-deck cages from 57 to 62 wk (previously housed on shavings, slats, and cages) did not differ, with APC ranging from 0.6 to 0.8 log(10) cfu/mL. Washing eggs continued to significantly reduce APC to below 0.2 log(10) cfu/mL. In experiment 3, the APC for unwashed eggs were within 0.4 log below the APC attained for unwashed eggs in experiment 1, although hen density was 28% of that used in experiment 1. Washing eggs further lowered the APC to 0.4 to 0.7 log(10) cfu/mL, a 2.7-log reduction. These results indicate that shell bacterial levels are similar after washing for eggs from hens housed in these caged and cage-free environments. However, housing hens in cages with manure removal belts resulted in lower APC for both unwashed and washed eggs (compared with eggs from hens housed in a room with shavings, slats, and cages).

Effect of stomaching on numbers of bacteria recovered from chicken skin.

Stomaching of skin samples releases only slightly more bacteria than a single rinse. Successive rinses, however, continue to remove almost as many bacteria as the first rinse. One hypothesis to explain this observation is that relatively violent treatment of skin generates smaller pieces of skin, thus increasing the net surface area and effectively sequestering bacteria in a water film on the skin pieces so that numbers of bacteria suspended in the rinsate do not increase. An experiment was conducted to determine whether inoculated marker bacteria are removed from the rinse liquid as skin pieces are stomached and naturally occurring bacteria are released. In each of 4 replications, 5 prechill broiler carcasses were collected from a commercial processing plant. Two 5-g pieces (n = 40) of breast skin were removed from each carcass and placed in a stomacher bag. An inoculum of 30 mL of 0.85% saline solution containing approximately 10(4) of nalidixic acid-resistant Salmonella enterica serovar Typhimurium per milliliter was added to each sample. Skin samples were hand-massaged for 30 s to mix the inoculum, after which a 1-mL aliquot was removed for enumeration of bacteria. A similar sample was taken after 4 min of vigorous stomaching of the skin sample. Bacterial counts recovered from the 30-s hand-massage were 4.3, 2.7, 2.6, and 3.7 log(10) cfu/mL of rinsate for aerobic bacteria, coliforms, Escherichia coli, and Salmonella, respectively. After stomaching, counts were 4.3, 2.9, 2.8, and 3.8, respectively. There was no difference in aerobic plate counts, but mean coliform and E. coli counts were significantly higher (P < 0.05) after stomaching. Numbers of inoculated Salmonella did not decrease. Breaking up the skin into smaller pieces by stomaching did not reduce the number of inoculated bacteria suspended in the rinsate.

Horizontal transmission of Salmonella and Campylobacter among caged and cage-free laying hens.

In each of five sequential trials, laying hens (56-72 wk of age) were challenged with Salmonella and Campylobacter, and 1 wk postinoculation, the challenged hens (n = 3) were commingled with nonchallenged hens (n = 12) in conventional wire cages, on all-wire slats, or on all-shavings floor housing systems. After 12 days, challenged and nonchallenged hens were euthanatized for sample collection. Ceca were aseptically collected from all hens, and the spleen, liver/gallbladder (LGB), lower (LRT) and upper (URT) reproductive tracts, and ovarian follicles (mature and immature) were collected from only the challenged hens after commingling. Samples were divided equally and cultured separately for Salmonella and Campylobacter. Differences in the horizontal transmission of the challenge Salmonella to nonchallenged hens housed in cages (12%), on slats (15%), and on shavings (14%) were not significantly different (P > 0.05) from the challenged pen-mate hens over the five trials. However, with the inclusion of residual environmental Salmonella, the recovery of Salmonella from nonchallenged hens housed in cages was lowest at 15%, intermediate for hens on slats at 20%, and highest for hens on shavings at 38%. Among challenged hens housed in cages, Salmonella was recovered from only 27% of the cecum and LRT samples. From challenged hens housed on slats, Salmonella was recovered from 38% of the cecum, 12% of the spleen, 19% of the LGB, 44% of the LRT, and 19% of the URT samples. From challenged hens housed on shavings, Salmonella was recovered from 31% of the cecum; 15% of the spleen, LGB, and URT; and 31% of the LRT samples. Horizontal transmission of Campylobacter among nonchallenged pen-mate hens was significantly lower for hens housed in cages at 28% than for hens on shavings at 47%, with hens on slats being intermediate at 36%. For challenged hens housed in cages, Campylobacter was recovered from 27% of the cecum, 13% of the LRT, 7% of the URT, and 17% of the follicle samples. Among the challenged hens housed on slats, Campylobacter was recovered from 44% of the cecum, 6% of the spleen, 19% of the LGB, 12% of the LRT, 6% of the URT, and 14% of the follicle samples. Among challenged hens housed on shavings, Campylobacter was recovered from 46% of the cecum, 8% of the LRT and URT, and 40% of the follicle samples. The overall results of this study indicate that the caged housing system provided the lowest horizontal transmission level of Salmonella and Campylobacter among egg-laying hens.

Colonization of a marker and field strain of Salmonella enteritidis and a marker strain of Salmonella typhimurium in vancomycin-pretreated and nonpretreated laying hens.

This study was conducted to evaluate the influence of a vancomycin pretreatment on the ability of marker (nalidixic-acid resistant) Salmonella Enteritidis (SE(M)), field Salmonella Enteritidis (SE(E)), and marker Salmonella Typhimurium (ST(M)) strains to colonize within the intestinal and reproductive tracts and translocate to other organs of leghorn laying hens. In each of three trials, caged laying hens (76, 26, and 33 wk ofage) were divided into six groups designated to receive SE(M), SE(F), or ST(M), and half were pretreated with vancomycin (n = 11-12 hens). Vancomycin-treated hens received 10 mg vancomycin in saline/kilogram body weight orally for 5 days to inhibit Gram-positive bacteria within the intestines. On Day 6, all hens were concurrently challenged by oral, intravaginal, and intracolonal routes with Salmonella and placed into separate floor chambers by Salmonella strain. Two weeks postinoculation, all hens were euthanatized and the ceca, spleen, liver/gall bladder (LGB), upper (URT), and lower (LRT) reproductive tracts, and ovarian follicles were aseptically collected, and analyzed for Salmonella. Results did not differ for the three hen's ages and were therefore combined. The vancomycin pretreatment also had no significant effect on the colonization ability of SE(M), SE(F) or ST(M), and therefore results were combined within Salmonella strain. The marker strain of Salmonella Enteritidis was recovered from 21% of ceca, 4% of LGB, 9% of LRT, and 17% of the fecal samples. The field strain of Salmonella Enteritidis was recovered from 88% of ceca, 96% of spleen, 92% of LGB, 30% of LRT, 4% of URT, 13% of follicle, and 42% of the fecal samples. The marker strain of Salmonella Typhimurium was recovered from 100% of ceca, 74% of spleen, 91% of LGB, 30% of LRT, 9% of URT, 9% of follicle, and 100% of the fecal samples. Among ceca, spleen, LGB, and fecal samples, SE(F) and ST(M) colonization was significantly greater than SE(M) colonization. Overall prevalence of Salmonella in the reproductive tracts of challenged hens was relatively low, ranging from 4% to 30%.

Comparison of the statistics of Salmonella testing of chilled broiler chicken carcasses by whole-carcass rinse and neck skin excision.

Whether a required Salmonella test series is passed or failed depends not only on the presence of the bacteria but also on the methods for taking samples, the methods for culturing samples, and the statistics associated with the sampling plan. The pass-fail probabilities of the 2-class attribute sampling plans used for testing chilled chicken carcasses in the United States and Europe were compared by calculation and simulation. Testing in the United States uses whole-carcass rinses (WCR), with a maximum number of 12 positives out of 51 carcasses in a test set. Those numbers were chosen so that a plant operating with a Salmonella prevalence of 20%, the national baseline result for broiler chicken carcasses, has an approximately 80% probability of passing a test set. The European Union requires taking neck skin samples of approximately 8.3 g each from 150 carcasses, with the neck skins cultured in pools of 3 and with 7 positives as the maximum passing score for a test set of 50 composite samples. For each of these sampling plans, binomial probabilities were calculated and 100,000 complete sampling sets were simulated using a random number generator in a spreadsheet. Calculations indicated that a 20% positive rate in WCR samples was approximately equivalent to an 11.42% positive rate in composite neck skin samples or a 3.96% positive rate in individual neck skin samples within a pool of 3. With 20% as the prevalence rate, 79.3% of the simulated WCR sets passed with 12 or fewer positive carcasses per set, very near the expected 80% rate. Under simulated European conditions, a Salmonella prevalence of 3.96% in individual neck skin samples yielded a passing rate of 79.1%. The 2 sampling plans thus have roughly equivalent outcomes if WCR samples have a Salmonella-positive rate of 20% and individual neck skin samples have a positive rate of 3.96%. Sampling and culturing methods must also be considered in comparing the different standards for Salmonella.

Comparison of neck skin excision and whole carcass rinse sampling methods for microbiological evaluation of broiler carcasses before and after immersion chilling.

Sampling protocols for detecting Salmonella on poultry differ among various countries. In the United States, the U.S. Department of Agriculture Food Safety and Inspection Service dictates that whole broiler carcasses should be rinsed with 400 ml of 1% buffered peptone water, whereas in the European Union 25-g samples composed of neck skin from three carcasses are evaluated. The purpose of this study was to evaluate a whole carcass rinse (WCR) and a neck skin excision (NS) procedure for Salmonella and Escherichia coli isolation from the same broiler carcass. Carcasses were obtained from three broiler processing plants. The skin around the neck area was aseptically removed and bagged separately from the carcass, and microbiological analysis was performed. The corresponding carcass was bagged and a WCR sample was evaluated. No significant difference (alpha

A comparison of methods to estimate nutritional requirements from experimental data.

1. Research papers use a variety of methods for evaluating experiments designed to determine nutritional requirements of poultry. Growth trials result in a set of ordered pairs of data. Often, point-by-point comparisons are made between treatments using analysis of variance. This approach ignores that response variables (body weight, feed efficiency, bone ash, etc.) are continuous rather than discrete. Point-by-point analyses harvest much less than the total amount of information from the data. Regression models are more effective at gleaning information from data, but the concept of "requirements" is poorly defined by many regression models. 2. Response data from a study of the lysine requirements of young broilers was used to compare methods of determining requirements. In this study, multiple range tests were compared with quadratic polynomials (QP), broken line models with linear (BLL) or quadratic (BLQ) ascending portions, the saturation kinetics model (SK) a logistic model (LM) and a compartmental (CM) model. 3. The sum of total residuals squared was used to compare the models. The SK and LM were the best fit models, followed by the CM, BLL, BLQ, and QP models. A plot of the residuals versus nutrient intake showed clearly that the BLQ and SK models fitted the data best in the important region where the ascending portion meets the plateau. 4. The BLQ model clearly defines the technical concept of nutritional requirements as typically defined by nutritionists. However, the SK, LM and CM models better depict the relationship typically defined by economists as the "law of diminishing marginal productivity". The SK model was used to demonstrate how the law of diminishing marginal productivity can be applied to poultry nutrition, and how the "most economical feeding level" may replace the concept of "requirements".

Transmission of Salmonella to broilers by contaminated larval and adult lesser mealworms, Alphitobius diaperinus (Coleoptera: Tenebrionidae).

The ability of the lesser mealworm, Alphitobius diaperinus (Panzer), commonly known as the darkling beetle, to transmit marker Salmonella Typhimurium to day-of-hatch broiler chicks was evaluated, as well as the spread to nonchallenged pen mates. In trial 1, day-of-hatch chicks were orally gavaged with 4 larval or 4 adult beetles that had been exposed to marker Salmonella-inoculated feed for 72 h. In addition, chicks were gavaged with the marker Salmonella in saline solution. These chicks were then placed into pens to serve as challenged broilers. In trial 2, all pens received 2 challenged chicks that were gavaged with larvae or beetles that had been exposed to marker Salmonella-inoculated feed for 24 h and then removed from the inoculated feed for a period of 7 d. At 3 wk of age, cecal samples from the marker Salmonella-challenged broilers and from 5 pen mates in trial 1, or 10 pen mates in trial 2, were evaluated for the presence of the marker Salmonella in their ceca, and at 6 wk of age, all remaining pen mates were sampled. To monitor the presence of the marker Salmonella within pens, stepped-on drag swab litter samples were taken weekly. For the Salmonella-saline pens, 29 to 33% of the broilers that had been challenged and 10 to 55% of the pen mates were positive at 3 wk of age, and only 2 to 6% had positive ceca at 6 wk. For the pens challenged with adult beetles, 0 to 57% of the challenged broilers and 20 to 40% of the pen mates had positive ceca at 3 wk, and 4 to 7% were positive at 6 wk. The pens challenged with larvae had the greatest percentage of marker Salmonella-positive broilers; 25 to 33% of the challenged broilers and 45 to 58% of pen mates were positive at 3 wk, and 11 to 27% were positive at 6 wk. These results demonstrated that ingestion of larval or adult beetles contaminated with a marker Salmonella could be a significant vector for transmission to broilers.

Recovery of bacteria from broiler carcasses after immersion chilling in different volumes of water, part 2.

Experiments were conducted to determine the relationship between poultry chilling water volume and carcass microbiology. In the first study, the volume of water used during immersion chilling was found to have a significant effect on the counts of bacteria recovered from broiler carcass halves; however, these volumes (2.1 and 16.8 L/kg) were extreme and did not reflect commercial levels. A second study using commercial chilling volumes was conducted with 3.3 L/kg (low) or 6.7 L/kg (high) distilled water in the chiller. Prechill broiler carcasses were removed from a commercial processing line, cut into left and right halves, and one-half of each pair was individually chilled in a bag containing low or high volume of water. Bags containing halves were submersed in a secondary chill tank containing approximately 150 L of an ice-water mix (0.6 degrees C). After 45 min, halves were removed, allowed to drip for 5 min, and rinsed with 100 mL of sterile water for 1 min. Rinses were analyzed for total aerobic bacteria, Escherichia coli, Enterobacteriaceae, and Campylobacter. When the numbers of bacteria in the half-carcass rinses (HCR) were compared, counts recovered from halves chilled in a low volume of water were the same as those recovered from the halves chilled with a high volume of water (P > 0.05). Levels found in the HCR ranged from 4.0 to 4.2 log(10) cfu/mL for aerobic bacteria, 3.3 to 3.5 log(10) cfu/mL for E. coli, 3.6 to 3.8 log(10) cfu/mL for Enterobacteriaceae, and 2.4 to 2.6 log(10) cfu/mL for Campylobacter. Data were also analyzed using a paired comparison t-test, and this analysis showed that there was no difference (P > 0.05) in the numbers of aerobic bacteria, E. coli, Enterobacteriaceae, or Campylobacter recovered from paired-halves chilled in different volumes of water. The present study shows that under the conditions outlined in this experiment, doubling the amount of water during immersion chilling (3.3 vs. 6.7 L/kg) did not improve the removal of bacteria from the surfaces of chilled carcasses.

Partitioning of external and internal bacteria carried by broiler chickens before processing.

Broiler chickens from the loading dock of a commercial processing plant were sampled to determine the incidence and counts of coliforms, Escherichia coli, and pathogenic bacteria. Feathers were removed by hand from ten 6-week-old chickens from each of seven different flocks and rinsed in 400 ml of 0.1% peptone water. Heads and feet were removed and rinsed, and the picked carcass was also rinsed, each in 200 ml. The ceca, colon, and crop were aseptically removed and stomached separately in 100 ml of peptone water. Campylobacter was present in six of the seven flocks. Salmonella was isolated from 50 of the 70 carcasses, with at least 2 positive carcasses in each flock, and five-tube most-probable-number (MPN) assays were performed on positive samples. Significantly (P < 0.05) more coliforms and E. coli were found in the ceca than in the feathers, which in turn carried more than the other samples, but total external and internal counts were roughly equivalent. Counts of Campylobacter were higher in the ceca and colon than in the other samples. Salmonella was isolated in external samples from 46 of the 50 positive carcasses compared with 26 positive internal samples or 17 positives in the ceca alone. The total MPN of Salmonella was approximately equivalent in all samples, indicating that contamination was distributed through all external and internal sampling locations. Salmonella-positive samples did not carry higher counts of coliforms or E. coli, and there were no significant correlations between the indicators and pathogens in any sample. Campylobacter numbers in the ceca were correlated with Campylobacter numbers in the feathers and colon, but Salmonella numbers in those samples were not correlated. The pattern of bacterial contamination before processing is complex and highly variable.

Evaluation of carcass scraping to enumerate bacteria on prechill broiler carcasses.

Experiments were conducted to evaluate a scraping method for enumerating bacteria on broiler carcasses. In experiment 1, coliforms and Escherichia coli were determined by the whole-carcass rinse (WCR) method and by scraping the skin surface and rinsing the blade (BR). In each of 2 replicate trials, 4 prechill broiler carcasses were collected from 2 different commercial processing plants. The WCR method was conducted on each carcass, then a blunt edge blade was used to scrape an area measuring approximately 80 cm(2) of the breast (front) skin and on the back of the carcass. After scraping, each blade and adhering residue was rinsed in 30 mL of 0.1% peptone. One milliliter of rinsate each from the WCR and BR was plated to determine total coliforms and E. coli. In experiment 2, 6 carcasses were collected from a processing plant in each of 2 replicate trials. Carcasses were split, with one half scraped on all skin surfaces, and the other half remaining unscraped as a control; all halves were then subjected to half-carcass rinses using 200 mL of 0.1% peptone. Coliforms and E. coli were enumerated. Results from both experiments are reported as log cfu/mL. In experiment 1, mean coliform WCR counts (5.1) were significantly higher (P < 0.05) than back BR (2.8), which were higher than front BR (2.2). Mean E. coli WCR counts (4.5) were higher than back BR (2.4), which were higher than front BR (1.6). The counts for BR adjusted for the greater surface area sampled by WCR were still lower than the WCR counts. Experiment 2 results showed no difference between control and scraped carcass halves for coliforms (4.7) or E. coli (4.6). Overall, results showed that scraping either prior to or after rinsing did not increase enumeration of coliforms or E. coli. Scraping could be a viable method to compare the numbers of bacteria on different areas of the same carcass.

Effect of external or internal fecal contamination on numbers of bacteria on prechilled broiler carcasses.

During processing, fecal material may contact broiler carcasses externally or internally. A study was conducted to determine the effect of external vs. internal fecal contamination on numbers of bacteria on broiler carcasses. In each of 3 trials, 12 carcasses just prior to evisceration were obtained from a commercial processing plant, placed on a shackle line, and eviscerated with commercial equipment in a pilot scale processing plant. Also, approximately 20 intestinal tracts were collected from the processing plant; then cecal contents were collected and pooled. One gram of cecal content was placed on the exterior breast skin (external), inside the carcass cavity (internal), or not applied (control). All carcasses were held 10 min, then placed on the shackle line and passed through a commercial inside-outside bird washer set at 552 kPa, 5 s dwell time, using approximately 189 L per min of tap water at ambient temperature. After a 1-min drip, whole carcass rinses were conducted on each carcass, and coliforms, Escherichia coli, and Campylobacter counts were determined and reported as log cfu/mL of rinse. External carcass contamination resulted in significantly higher (P<0.05) coliform, E. coli, and Campylobacter numbers than internal contamination (5.0 vs. 4.5, 4.9 vs. 4.2, and 3.6 vs. 2.6, respectively). Control carcass counts were significantly lower than external or internal carcass contamination counts for coliforms (3.7), E. coli (3.6), and Campylobacter (2.2). External contamination resulted in higher numbers of bacteria after carcass washing, but carcasses with internal contamination still have higher numbers of bacteria after washing than carcasses without applied contamination.

Comparison of four sampling methods for the detection of Salmonella in broiler litter.

Experiments were conducted to compare litter sampling methods for the detection of Salmonella. In experiment 1, chicks were challenged orally with a suspension of naladixic acid-resistant Salmonella and wing banded, and additional nonchallenged chicks were placed into each of 2 challenge pens. Nonchallenged chicks were placed into each nonchallenge pen located adjacent to the challenge pens. At 7, 8, 10, and 11 wk of age the litter was sampled using 4 methods: fecal droppings, litter grab, drag swab, and sock. For the challenge pens, Salmonella-positive samples were detected in 3 of 16 fecal samples, 6 of 16 litter grab samples, 7 of 16 drag swabs samples, and 7 of 16 sock samples. Samples from the nonchallenge pens were Salmonella positive in 2 of 16 litter grab samples, 9 of 16 drag swab samples, and 9 of 16 sock samples. In experiment 2, chicks were challenged with Salmonella, and the litter in the challenge and adjacent nonchallenge pens were sampled at 4, 6, and 8 wk of age with broilers remaining in all pens. For the challenge pens, Salmonella was detected in 10 of 36 fecal samples, 20 of 36 litter grab samples, 14 of 36 drag swab samples, and 26 of 36 sock samples. Samples from the adjacent nonchallenge pens were positive for Salmonella in 6 of 36 fecal droppings samples, 4 of 36 litter grab samples, 7 of 36 drag swab samples, and 19 of 36 sock samples. Sock samples had the highest rates of Salmonella detection. In experiment 3, the litter from a Salmonella-challenged flock was sampled at 7, 8, and 9 wk by socks and drag swabs. In addition, comparisons with drag swabs that were stepped on during sampling were made. Both socks (24 of 36, 67%) and drag swabs that were stepped on (25 of 36, 69%) showed significantly more Salmonella-positive samples than the traditional drag swab method (16 of 36, 44%). Drag swabs that were stepped on had comparable Salmonella detection level to that for socks. Litter sampling methods that incorporate stepping on the sample material while in contact with the litter appear to detect Salmonella in greater incidence than traditional sampling methods of dragging swabs over the litter surface.

Broiler carcass bacterial counts after immersion chilling using either a low or high volume of water.

A study was conducted to investigate the bacteriological impact of using different volumes of water during immersion chilling of broiler carcasses. Market-aged broilers were processed, and carcasses were cut into left and right halves along the keel bone immediately after the final bird wash. One half of each carcass pair was individually chilled at 4 degrees C in a separate bag containing either 2.1 L/kg (low) or 16.8 L/kg (high) of distilled water. Carcass halves were submersed in a secondary chill tank containing approximately 150 L of an ice-water mix (0.6 degrees C). After chilling for 45 min, carcass halves were rinsed with 100 mL of sterile water for 1 min. Rinses and chill water were analyzed for total aerobic bacteria (APC), Escherichia coli, Enterobacteriaceae, and Campylobacter. After chilling with a low volume of water, counts were 3.7, 2.5, 2.6, and 2.1 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. When a high volume of chill water was used, counts were 3.2, 1.7, 1.6, and 1.8 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. There was no difference in bacterial counts per milliliter of chill water among treatments. These results show that using additional water during immersion chilling of inoculated broilers will remove more bacteria from the carcass surfaces, but numbers of bacteria per milliliter in the chiller water will remain constant. The bacteriological impact of using more water during commercial immersion chilling may not be enough to offset economic costs.

Release of Escherichia coli from feathered and featherless broiler carcasses in warm water.

Release of bacteria from individual broiler carcasses in warm water was measured as a model of bacterial contamination of scald water. Immediately after shackling and electrocution, feathered and genetically featherless broiler carcasses (n = 24 of each) were immersed individually in 42 degrees C, air-agitated tap water for 150 s. Although any visible fecal material expelled as a result of electrocution was removed before sampling, carcass condition was typical for market-age broilers subjected to 12 h of feed withdrawal. Duplicate water samples were taken at 10, 30, 70, 110, and 150 s, and Escherichia coli counts were determined. Samples of initial tap water and contaminated water approximately 2 min after removal of carcasses indicated that E. coli could not be detected in the original water source and that mortality of E. coli in the warm water was negligible. Mean numbers of E. coli released were 6.2 and 5.5 log(10) (cfu/carcass) at 150 s for feathered and featherless carcasses, respectively. For both feathered and featherless carcasses, the rate of release of E. coli was highest in the first 10 s, and the rate declined steadily during the remaining sampling period. This result is compatible with published reports of sampling of operating multiple-tank scalders, indicating that a high proportion of total bacteria in a multiple-tank scalder are in the first scald tank that carcasses enter. Higher numbers of E. coli released from feathered carcasses are probably due to the much greater surface area of contaminated feathers compared with the skin of featherless carcasses.