Biomedical subjects

N J Stern

Publications and source records attributed to N J Stern.

At least 19 recordsLinked to original sources

PubMed2006

The ability of flagellum-specific Proteus vulgaris bacteriophage PV22 to interact with Campylobacter jejuni flagella in culture.

BACKGROUND: There has been a recent resurgent interest in bacteriophage biology. Research was initiated to examine Campylobacter jejuni-specific bacteriophage in the Russian Federation to develop alternative control measures for this pathogen. RESULTS: A C. jejuni flagellum-specific phage PV22 from Proteus vulgaris was identified in sewage drainage. This phage interacted with C. jejuni by attachment to flagella followed by translocation of the phage to the polar region of the bacterium up to the point of DNA injection. Electron microscopic examination revealed adsorption of PV22 on C. jejuni flagella after a five minute incubation of the phage and bacteria. A different phenomenon was observed after incubating the mix under the same conditions, but for twenty minutes or longer. Phage accumulated primarily on the surface of cells at sites where flagella originated. Interestingly, PV22 did not inject DNA into C. jejuni and PV22 did not produce lytic plaques on medium containing C. jejuni cells. The constant of velocity for PV22 adsorption on cells was 7 x 10(-9) ml/min. CONCLUSION: It was demonstrated that a bacteriophage that productively infects P. vulgaris was able to bind C. jejuni and by a spot test that the growth of C. jejuni was reduced relative to control bacteria in the region of phage application. There may be two interesting applications of this effect. First, it may be possible to test phage PV22 as an antimicrobial agent to decrease C. jejuni colonization of the chicken intestine. Second, the phage could potentially be utilized for investigating biogenesis of C. jejuni flagella.

Adsorption↗

PubMed2006

Enumeration and identity of Campylobacter spp. in Italian broilers.

Transmission of Campylobacter to humans has been prominently associated with mishandling or improperly preparing contaminated poultry carcasses. The number of organisms per carcass represents an important measure of human exposure to the agent. Therefore, we wished to estimate this public exposure over 1 yr among Italian broiler carcasses. We sampled 213 broiler carcasses from rinse water samples collected from a single slaughterhouse. Groups of carcasses had mean processed weights ranging from 1.2 to 2.7 kg. These were produced from 22 commercial broiler chicken flocks collected from 12 different farms, 3 of which were seasonally tested. Carcasses were rinsed with sterile water, and the rinse suspension was then serially diluted and spread-plated directly onto Campy-Cefex agar plates. One to 5 typical Campylobacter colonies per plate were identified by polymerase chain reaction as Campylobacter thermo-tolerant species. The overall estimated mean count per carcass in our study was 5.16 +/- 0.80 log10 cfu. This value increased in summer and autumn, as well as on carcasses collected from farms located > 100 km far from the slaughterhouse. A total of 678 Campylobacter colonies were identified by polymerase chain reaction. The majority of isolates were classified as Campylobacter jejuni (49.2%) or Campylobacter coli (47.5%). The overall number of C. jejuni was significantly higher on 1) carcasses weighing > 2 kg, 2) carcasses belonging to flocks with > 10,000 birds, and 3) carcasses collected from farms located > 100 km from the slaughterhouse. Moreover, among farms tested seasonally, C. jejuni was significantly greater than C. coli in winter. These data provide the first results of a continuing survey on Campylobacter loads and species identification from Italian broiler carcasses and represents an important baseline to estimate the human exposure to Campylobacter in Italy.

Abattoirs↗

PubMed2006

Bacteriocins reduce Campylobacter colonization and alter gut morphology in turkey poults.

Campylobacter is a leading cause of food-borne illness in the United States. Recent evidence has demonstrated that bacteriocins produced by Bacillus circulans and Paenibacillus polymyxa reduce cecal Campylobacter colonization in broiler chickens infected with Campylobacter jejuni. As Campylobacter coli is the most prevalent Campylobacter isolate recovered in turkeys, the objectives of the present study were to evaluate the efficacy of these bacteriocins against C. coli colonization and their influence on the gastrointestinal architecture of young turkeys. In 3 separate trials, a total of 135 day-of-hatch poults (n = 45/trial) were orally challenged on d 3 with approximately 10(6) cfu of a mixture of 3 C. coli isolates. Immediately before bacteriocin treatment (d 10), cecal Campylobacter concentrations averaged 1.1 x 10(7) cfu/ g of cecal contents (n = 15/trial). On d 10 to 12 posthatch, 2 bacteriocin treatment groups were given free access to feed supplemented with purified, microencapsulated bacteriocins, whereas the positive control treatment group had access to untreated feed (n = 10/treatment group per trial). At the end of the 3-d dosing period, ceca and duodenal loops were collected for analysis. In each of the 3 separate trials, treatment with bacteriocin eliminated detectable ceca Campylobacter concentrations (detection limit, 1 x 10(2) cfu/g of cecal contents) vs. controls (1.0 x 106 cfu of Campylobacter/g of cecal contents). Duodenum crypt depth and goblet cell numbers were also reduced in turkeys treated with either bacteriocin vs. controls (P < 0.05). The dynamic reduction in crypt depth and goblet cell density in turkeys dosed with bacteriocin may provide clues to how bacteriocins inhibit enteric Campylobacter.

Animal Feed↗

PubMed2006

Isolation of a Lactobacillus salivarius strain and purification of its bacteriocin, which is inhibitory to Campylobacter jejuni in the chicken gastrointestinal system.

We evaluated anti-Campylobacter jejuni activity among >1,200 isolates of different lactic acid bacteria. Lactobacillus salivarius strain NRRL B-30514 was selected for further study. The cell-free, ammonium sulfate precipitate from the broth culture was termed the crude antimicrobial preparation. Ten microliters of the crude preparation created a zone of C. jejuni growth inhibition, and growth within the zone resumed when the crude preparation was preincubated with proteolytic enzymes. Bacteriocin OR-7, derived from this crude preparation, was further purified using ion-exchange and hydrophobic-interaction chromatography. The determined amino acid sequence was consistent with class IIa bacteriocins. Interestingly, OR-7 had sequence similarity, even in the C-terminal region, to acidocin A, which was previously identified from L. acidophilus and had activity only to gram-positive bacteria, whereas OR-7 had activity to a gram-negative bacterium. Bacteriocin activity was stable following exposure to 90 degrees C for 15 min, also consistent with these types of antibacterial peptides. The purified protein was encapsulated in polyvinylpyrrolidone and added to chicken feed. Ten day-of-hatch chicks were placed in each of nine isolation units; two groups of birds were challenged with each of four C. jejuni isolates (one isolate per unit). At 7 days of age, one group of birds was treated with bacteriocin-emended feed for 3 days, and one group was left untreated. At 10 days of age, the birds were sacrificed and the challenge strain was enumerated from the bird cecal content. Bacteriocin treatment consistently reduced colonization at least one millionfold compared with levels found in the untreated groups. Nonchallenged birds were never colonized by C. jejuni. Bacteriocin from L. salivarius NRRL B-30514 appears potentially very useful to reduce C. jejuni in poultry prior to processing.

Amino Acid Sequence↗

PubMed2005

Occurrence of Campylobacter spp. in cecal contents among commercial broilers in iceland.

Campylobacter jejuni remains the most frequently reported bacterial cause of human gastroenteritis in Nordic countries. The primary source of transmission to humans is suggested as mishandled raw poultry or consuming improperly prepared chicken. The focus of this report was to characterize the prevalence and cell numbers of the organism within the commercial Icelandic poultry industry. Commercial broiler flocks were sampled from May 2001 through 2003 in a total population study. At the slaughter plant, 40 randomly selected ceca were obtained from each flock, pooled into four samples containing 10 ceca each, and analyzed. Cell numbers and prevalence of Campylobacter spp. were estimated by direct plating of dilutions onto Campy-Cefex agar and incubating the plates at 42 degrees C under microaerobic atmosphere; colonies were confirmed as Campylobacter spp. by microscopy and latex agglutination to provide quantification of cell numbers per gm of cecal material. A total of 15.4% of the flocks carried the organism at at a maximum cell number of 8.1 x 10(7) cfu/g, having a mean raw count of colonized birds at 1.3 x 10(7) cfu/g (geometric mean of 1.5 x 10(6)). During the 3 years of sampling, the prevalence ranged from 17.6% to 17.3% to 12.7% for slaughter years 2001, 2002, and 2003, respectively. Isolation rates varied with numbers of catch lots (groups of birds taken for slaughter)/flock; with one catch lot/flock, the prevalence was 13.7%, with two 17.5%, and with three 33.3%. With increased flock size, isolation rates also increased; flocks of greater than 5,000 birds had a prevalence of 12.0% positive, 14.0% of flocks with 5,000-10,000 birds were positive, and 25.5% of flocks with more than 10,000 birds were positive for Campylobacter spp. Isolation rates varied with the processing lines: M was positive at 17.3%, B was positive at 10.1%, and G at 17.2%. Flocks were more frequently colonized in the warmer months, and younger birds were less frequently colonized than were older slaughtered birds. This study provides descriptive microbiology pertaining to Iceland broilers in a total population study.

Abattoirs↗

PubMed2005

Isolation of DNA for PCR assays from noncultivable Campylobacter jejuni isolates.

Isolates of Campylobacter jejuni shipped internationally often arrive in a noncultivable state. We describe a PCR-based methodology whereby phylogenetic information can be recovered from noncultivable C. jejuni stored in Wang's transport medium. The robustness of this methodology was initially tested using 5 previously characterized strains of C. jejuni isolated from various sources associated with poultry production. These isolates were stored in Wang's transport medium before being subjected to 1 of 5 treatments designed to render the stored cells noncultivable: prolonged storage at room temperature, prolonged incubation at 42 degrees C, multiple rounds of freezing and thawing, boiling, or contamination with Pseudomonas aeruginosa (ATCC 27853). This method resulted in DNA appropriate for PCR. An approximately 400-nucleotide amplicon from the flaA gene and an approximately 800-nucleotide amplicon from 16S rDNA were readily obtained, and a 1.5-kb section of the flaA locus was amplified from about half of the samples. These results indicate that this method may be useful for isolate typing schemes based on PCR amplification of Campylobacter DNA, including flaA short variable region (flaA SVR) sequencing, multilocus sequence typing (MLST), and flaA PCR-RFLP. By using this method, isolates unrecoverable from transport medium can still be used to provide phylogenetic information for epidemiological studies.

Campylobacter jejuni↗

PubMed2004

Distribution and characterization of Campylobacter spp. from Russian poultry.

The distribution of Campylobacter spp. on 13 poultry farms (broiler chicken, quail, pheasant, peacock, and turkey) from eight regions (Vladimir, Vologda, Voronezh, Kaluga, Liptsk, Moscow, Orenburg, and Orel) in Russia was surveyed. Intestinal materials were plated onto Campylobacter-selective medium and plates were incubated microaerobically at 42 degrees C for 24 or 48 h. Identification was based on colonial morphology, microscopic examination, and biochemical tests; latex agglutination assays were used for confirmation. In total, 116 isolates were derived from 370 samples. Isolation rates were similar, regardless of whether the birds were from small or large broiler production farms. Susceptibility of 48 representative (from these production sources) strains of Campylobacter spp. to 38 antimicrobial compounds was determined by disk diffusion assays. All strains tested were sensitive to amikacin, gentamycin, sisomycin, chloramphenicol, imipenem, oleandomycin, erythromycin, azitromycin, and ampicillin. The strains were also sensitive to 100 microg/disk of carbenicillin, fluoroquinolones, and to nitrofurans. Fluoroquinolone sensitivity was most notable and may be related to its limited application in poultry production within Russia. Hippurate and ribosomal RNA gene primers were developed and used to distinguish Campylobacter jejuni and Campylobacter coli and to provide a measure of strain discrimination. The combination of PCR analysis and randomly amplified polymorphic DNA (RAPD) typing were conducted for selected isolates. The various poultry species and the different locations yielded Campylobacter isolates with discrete randomly amplified polymorphic DNA patterns. The distribution and substantial diversity of Campylobacter spp. isolates appears similar to that previously reported in other countries.

Animals↗

PubMed2003

Campylobacter spp. in Icelandic poultry operations and human disease.

We describe the observed relationship of campylobacter in poultry operations to human cases in a closed environment. During 1999 in Iceland, domestic cases of campylobacteriosis reached peak levels at 116/100,000 and in 2000 dropped to 33/100,000. Approximately 62% of broiler carcass rinses were contaminated with Campylobacter spp. in 1999. During 2000, only 15% of the broiler flocks tested Campylobacter spp. positive. In 2000, carcasses from flocks which tested positive on the farms at 4 weeks of age were subsequently frozen prior to distribution. We suggest that public education, enhanced on-farm biological security measures, carcass freezing and other unidentified factors, such as variations in weather, contributed to the large reduction in poultry-borne campylobacteriosis. There is no immediate basis for assigning credit to any specific intervention. We continue to seek additional information to understand the decline in campylobacteriosis and to create a risk assessment model for Campylobacter spp. transmission through this well defined system.

Abattoirs↗

PubMed2003

Enumeration of Campylobacter spp. in broiler feces and in corresponding processed carcasses.

Twenty north Georgia commercial flocks of broiler chickens sampled in 1995 and 11 flocks sampled in 2001 were tested for Campylobacter spp. Direct plating on Campy-Cefex agar was carried out to determine levels of Campylobacter colonization within each flock through the enumeration of the organism in 50 fresh fecal samples 1 day prior to slaughter. The next morning, these flocks were the first to be processed, and levels of the organism per carcass before the chilling operation (50 carcasses per flock) in 2001 and after the chilling operation (50 carcasses per flock) in both 1995 and 2001 were estimated. Levels of the organism on freshly processed broiler carcasses were estimated by the same methods in 1995 and 2001, and a significant reduction from an average of 10(4.11) CFU per carcass in 1995 to an average of 10(3.05) CFU per carcass in 2001 was observed. Levels of Campylobacter spp. found in production and in processing were not strongly correlative, indicating the existence of complex parameters involving production factors and variables associated with flock transport and the processing of the broilers. The reduction in Campylobacter levels on processed carcasses may have contributed to the reduction in the frequency of human disease observed by the Centers for Disease Control during the same period. These data characterize the distribution of Campylobacter in north Georgia poultry operations and should assist in the development of risk assessment models for Campylobacter spp. The results obtained in this study suggest that the implementation of antimicrobial interventions by the poultry industry has already reduced consumer exposure to the organism.

Animals↗

PubMed2002

Molecular subtype analyses of Campylobacter spp. from Arkansas and California poultry operations.

Campylobacter isolates from diverse samples within broiler production and processing environments were typed by using flaA short variable region DNA sequence analysis. Sixteen flocks from four different farms representing two broiler producers in Arkansas and California were analyzed. Fourteen of the flocks (87.5%) were Campylobacter-positive; two remained negative throughout the 6-week rearing period. In general, multiple clones were present within a flock. Additionally, clones found within a flock were also present on the final product, although the diversity of Campylobacter spp. on the final product appeared to be reduced relative to that observed within the flock. Comparison of clones between flocks on the same farm revealed that some clones of Campylobacter persisted in multiple flocks. Furthermore, some clones were identified across the two farms that were under the same management. In two sampling periods, environmental isolates were positive for Campylobacter prior to flock shedding. Environmental samples associated with five additional flocks were positive for Campylobacter concomitantly with recovery of Campylobacter from the birds. Analysis of the environmental isolates that were positive prior to flock shedding demonstrated that in some instances the environmental isolates possessed genotypes identical to those of isolates originating from the flock, while in other cases the environmental isolates possessed genotypes that were distantly related to isolates obtained from the flock. Analyses of environmental isolates that tested positive concurrently with the positive isolates from the flocks demonstrated varied results; in some instances the environmental isolates possessed genotypes identical to those of isolates originating from the flock, while in other cases the environmental isolates possessed genotypes that were distantly related to isolates obtained from the flock. These data suggest that the external environment may contribute to Campylobacter contamination during poultry production and processing. However, environmental contamination with Campylobacter does not appear to be the sole contributing factor.

Animals↗

PubMed2002

Serotyping and ribotyping of Salmonella using restriction enzyme PvuII.

The subtyping and identification of bacterial pathogens throughout food processing and production chains is useful to the new hazard analysis critical control point-based food safety plans. Traditional manual serotyping remains the primary means of subtyping Salmonella isolates. Molecular biology techniques, however, offer the promise of more rapid and sensitive subtyping of Salmonella. This study evaluates the potential of restriction enzyme PvuII, followed by probing with the rRNA operon from Escherichia coli, to generate serotype-specific DNA fingerprints. A total of 32 identified serotypes were found with an overall agreement in 208 of the 259 (80%) isolates tested between U.S. Department of Agriculture serotype identification and riboprint serotype identification. Many of the isolates that did not correlate were serotype identified as Salmonella Montevideo, which indicates that for this serotype, there are multiple ribotypes. When Salmonella Montevideo isolates were not included, the ribotype identification agreed with serotyping in 207 of the 231 (90%) isolates. The primary outcome of any ribotyping procedure is to give distinct ribotype patterns. This extensive poultry epidemiological study demonstrates that, in addition to ribotype patterns, the identification of isolates to known serotypes provides the investigator with additional information that can be more useful than traditional epidemiology and isolate identification studies.

Animals↗

PubMed2002

Survival of Campylobacter jejuni in biofilms isolated from chicken houses.

Campylobacter jejuni is a thermophilic and microaerophilic enteric pathogen associated with poultry. Biofilms may be a source of C. jejuni in poultry house water systems since they can protect constituent microorganisms from environmental stress. In this study, the viability of C. jejuni in biofilms of gram-positive chicken house isolates (P1, Y1, and W1) and a Pseudomonas sp. was determined using a cultural method (modified brucella agar) and direct viable count (DVC). Two-day biofilms grown on polyvinyl chloride (PVC) coupons in R2A broth at 12 and 23 degrees C were incubated with C. jejuni for a 6-h attachment period. Media were then refreshed every 24 h for 7 days to allow biofilm growth. Two-day biofilms of P1, Y1, and Pseudomonas spp. enhanced attachment (P < 0.01) of C. jejuni (4.74, 4.62, and 4.78 log cells/cm2, respectively) compared to W1 and controls without preexisting biofilm (4.31 and 4.22 log cells/cm2, respectively). On day 7, isolates P1 and Y1 and Pseudomonas biofilms covered 5.4, 7.0, and 21.5% of the surface, respectively, compared to 4.9% by W1. Viable C. jejuni on the surface decreased (P < 0.05) with time, with the greatest reduction occurring on surfaces without a preexisting biofilm. The number of viable C. jejuni determined by DVC was greater than that determined by the cultural method, indicating that C. jejuni may form a viable but nonculturable state within the biofilm. Both DVC and the cultural method indicate that biofilms enhance (P < 0.01) the survival of C. jejuni during incubation at 12 and 23 degrees C over a 7-day period.

Animals↗

PubMed2001

Comparison of mucosal competitive exclusion and competitive exclusion treatment to reduce Salmonella and Campylobacter spp. colonization in broiler chickens.

Control of Salmonella spp. during the earliest phases of broiler production may provide the best opportunity to reduce human pathogens on processed broiler carcasses. Application of the "Nurmi concept" has been demonstrated to be an effective means in reducing Salmonella colonization among broiler chicks. In 1989, Aho et al. developed a competitive exclusion (CE) culture for control of Salmonella spp., whereas a mucosal competitive exclusion culture (MCE) developed in the United States was originally created to control Campylobacter colonization (Stern et al., 1995). The major differences in the two patents were the higher level of anaerobic culture required, the degree of epithelial scraping and washing of the ceca, media used for subculturing, and the culture incubation temperatures (35 C vs. 42 C). The CE and MCE were compared for efficacy in reducing Salmonella and Campylobacter colonization in broiler chicks. Nine adult birds (three for each of three replicates) were slaughtered, and each of a bird's paired ceca were used to produce corresponding antagonistic microflora, which were administered to day-of-hatch chicks. The chicks (a total of 210) were challenged 24 h later with Salmonella and Campylobacter and were killed 1 wk later, and levels of the pathogens were determined. Ninety CE-treated birds were significantly more colonized by Salmonella typhimurium than those 90 chicks treated with the MCE microflora (3.97 log 10 cfu/g cecal contents vs. 1.25 log 10 cfu/g cecal contents). Also, Campylobacter spp. colonization of these birds was significantly higher for CE-treated birds when compared with MCE-treated birds (6.96 log 10 cfu/g cecal contents vs. 5.03 log 10 cfu/g cecal contents). These results can be useful in developing intervention strategies to reduce chicken colonization by Salmonella and Campylobacter.

Animals↗

PubMed2001

Detection of Campylobacter spp. in ceca and crops with and without enrichment.

The purpose of this experiment was to determine how sampling method (direct plating or enrichment) affected the rate of Campylobacter spp. isolation from crop and cecal samples. In four separate trials, 32 New York-dressed broiler carcasses were obtained from commercial plants (n = 128). Crops and ceca were removed aseptically, direct plated, and enriched. Samples were direct-plated on Campy-Cefex plates that were incubated at 42 C for 36 to 48 h under a microaerobic atmosphere (5% O2, 10% CO2, 85% N2). After direct plating, samples were enriched in Bolton broth at 37 C for 4 h and 42 C for 20 h under a microaerobic atmosphere before plating onto Campy-Cefex plates. Campylobacter spp. was detected in 95.3% of direct-plated crop samples and 99.2% of enriched crop samples. Campylobacter spp. was detected in 100% of direct-plated cecal samples and 63.3% of enriched cecal samples. All 128 crop and cecal samples were positive for the organism by one or both methods. Mean counts of Campylobacter spp. were 3.6 log10 cfu/g of crop sample and 6.8 log10 cfu/g of cecal sample. For these two sample types, both of which tend to be contaminated with many viable cells, direct plating is sufficient for isolation of Campylobacter. Direct plating also provides an estimate of contamination level. Enrichment of cecal samples resulted in a decreased rate of detection and did not allow estimation of numbers of Campylobacter. The large numbers of non-Campylobacter species that inhabit the intestinal tract may out-compete Campylobacter during enrichment, confounding detection.

Animals↗

PubMed2001

Competitive exclusion of heterologous Campylobacter spp. in chicks.

Chicken and human isolates of Campylobacter jejuni were used to provide oral challenge of day-old broiler chicks. The isolation ratio of the competing challenge strains was monitored and varied, depending upon the isolates used. A PCR-restriction fragment length polymorphism assay of the flagellin gene (flaA) was used to discriminate between the chick-colonizing isolates. Our observations indicated that the selected C. jejuni colonizers dominated the niche provided by the chicken ceca. Chicken isolates from the flaA type 7 grouping generally had numerical superiority over the human isolates when they were administered in our 1-day-old chick model. Our results suggest that it is possible to use combinations of C. jejuni chicken isolates as a defined bacterial preparation for the competitive exclusion of human-pathogenic C. jejuni in poultry.

Animals↗

PubMed2001

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.

Animals↗

PubMed2001

Colonization of broiler chicks by Salmonella typhimurium definitive phage type 104.

The prevalence of an antibiotic-resistant strain of Salmonella Typhimurium definitive phage type 104 (DT104) has increased dramatically in recent years resulting in increased morbidity and mortality in both animals and humans. Colonization and shedding of Salmonella Typhimurium DT104 was studied in broiler chickens in two trials. In trial 1, 180 day-of-hatch chicks (n = 60 per group, n = 30 per replicate) were challenged with 10(6) CFU DT104 (wild-type isolate from poultry) or were commingled with a seeder chick challenged with 10(6) CFU DT104. In trial 2, 360 day-of-hatch chicks (n = 120 per treatment, n = 30 per rep) were divided into three groups. Chicks in the susceptible group were commingled with two seeder chicks that were orally challenged with 10(7) CFU/bird of a pan-sensitive strain of Salmonella Typhimurium DT104. Chicks in the resistant group were commingled with two seeder chicks that were orally challenged with 10(7) CFU/bird DT104 used in trial 1. For both trials, a control group was not exposed to DT104, composite fecal samples were evaluated twice weekly for levels of Salmonella shedding and 20 chicks per group were necropsied weekly and their cecal contents were cultured. At hatch all groups were colonized with naturally occurring Salmonella Senftenberg and Salmonella Mbandaka (trial 1) or Salmonella Senftenberg and Salmonella Ohio (trial 2) prior to exposure to DT104. Throughout the study, the level of Salmonella spp. shedding in feces (trial 1 means 3.1, 2.9, and 3.0 log10 CFU per g feces for challenged, seeder, and control groups, respectively) or ceca (trial 2 means 2.9. 2.9. and 2.5 log10 CFU per g ceca for resistant, susceptible, and control groups, respectively) did not differ among groups. In trial 1, colonization of DT104 remained constant at higher levels in the challenged group (mean 87%, P < 0.01), increased over time in the seeder group (10 to 50%, P < 0.02) and was not recovered from the control chicks. Salmonella Mbandaka colonization remained steady within each group with challenge and seeder groups maintaining higher levels of colonization than the control group. Salmonella Senftenberg colonization levels tended to decline (P = .058) over time in the challenged group (20 to 0%) and significantly decreased (P < 0.01) over time for both the seeder (80 to 0%) and control chicks (85 to 10%). In trial 2, the percentage of chicks colonized with susceptible DT104 declined (r = 0.90, P < 0.05) over the course of the trial from 45 to 0%, while recovery of the resistant DT104 persisted at a mean percentage of 27%. DT104 was not recovered from the control chicks. Salmonella Ohio colonization levels tended to decline (r = 0.79, P > 0.05) over time in the control group (75 to 20%) and significantly decreased (P < 0.05) over time in both susceptible and resistant groups (40 to 10%, r = 0.82 and 55 to 5%, r = 0.85, respectively). Salmonella Senftenberg was recovered from the control group at low frequency throughout the trial and was not recovered from the other groups. For either trial, no apparent affect on morbidity or mortality was observed. Introduction of DT104 by commingling may induce colonization resulting in persistent high levels of shedding in flocks simultaneously with other Salmonella species.

Animals↗

PubMed2001

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.

Age Factors↗