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N J Stern

Publications and source records attributed to N J Stern.

At least 37 records · Page 2Linked to original sources
PubMed2001

Difficulty in recovering inoculated Campylobacter jejuni from dry poultry-associated samples.

We inoculated 5 cm2 of clean chick pads, 5 g of clean pine shavings, and fresh unsanitized broiler breeder eggshell halves with a cell suspension of Campylobacter jejuni in physiological saline. Inoculation levels were 10(2), 10(3), or 10(4) cells per sample. The samples were allowed to remain at room temperature for 15, 30, or 60 min before addition of enrichment broth. When chick pad samples were inoculated with 102 cells, by 15 min 40% of the samples had detectable levels of Campylobacter, and by 30 to 60 min Campylobacter could be detected in only 20% of the samples. With samples of pine shavings, only 25% of those inoculated with 103 cells were positive for Campylobacter after 15 min and only 5% were positive for Campylobacter after 30 min. When 104 cells were inoculated onto litter, Campylobacter was recovered from 20% of the samples at 15 min and 15% of the samples after 30 min. Eggshells were also found to be a harsh environment. When the inoculum was 102 at 15 min, 8 of 10 samples were positive for Campylobacter but at 60 min only 10% of the samples remained positive for Campylobacter. The current cultural methods may not be adequate for recovering low numbers of Campylobacter from dry samples. Campylobacter may be present but culturally undetectable in the commercial hatchery and hatchery environment.

Animals↗
PubMed2001

Comparison of methods for recovery and enumeration of Campylobacter from freshly processed broilers.

Most traditional Campylobacter detection and enumeration procedures are difficult and time consuming. Estimations of Campylobacter populations by the most probable number (MPN) method are especially laborious. The objective of this collaborative study, performed in duplicate in Agricultural Research Service and Food Safety Inspection Service laboratories, was to compare two MPN procedures (utilizing different selective enrichment broths and plating media) to the direct plating technique for enumeration of Campylobacter from freshly processed (postchill, postdrip) broiler chicken carcasses. Results obtained from the direct plating of carcass rinse samples on Campy-cefex agar were not significantly different (P > 0.05) from an MPN procedure employing Hunt's Campylobacter selective enrichment broth followed by recovery on modified Campylobacter charcoal differential agar. However, both of these procedures provided significantly (P < 0.05) better recovery than a second MPN procedure using Rosef's selective enrichment broth followed by plating on Mueller-Hinton blood agar with antibiotics. The direct plating method offers a more simple, less expensive, more rapid alternative to traditional MPN procedures for estimating Campylobacter populations associated with freshly processed broiler carcasses.

Animals↗
PubMed2000

Commercial field trial evaluation of mucosal starter culture to reduce Salmonella incidence in processed broiler carcasses.

A series of four paired-house studies was conducted in Arkansas, Alabama, and Georgia (two farms) to determine the efficacy of Mucosal Starter Culture (MSC) in eliminating or reducing salmonellae in broiler chickens. Randomly designated chicks were treated twice with MSC. First they were sprayed with an MSC solution using a spray vaccination cabinet in the hatchery, and then they received MSC in the first drinking water at the growing house. Chicks were grown in identically constructed and equipped paired houses managed by the same grower. At the end of grow-out, broilers were tested for the presence of salmonellae on the farm and during processing. In three trials where no hatchery salmonellae were found, less salmonellae were found on MSC-treated chickens compared to untreated chickens. On the farm at the end of grow-out, salmonellae were detected in 54 of 150 untreated control chickens compared to 40 of 180 MSC-treated chickens. In the processing plant, significantly (P < or = 0.05) more salmonellae were detected on prechill untreated control carcasses (23 of 180) compared to MSC-treated carcasses (12 of 180) and on untreated postchill processed carcasses (9 of 180) compared to MSC-treated carcasses (0 of 180). In one trial where appreciable (28% of egg shell samples) salmonellae was found before treatment with the MSC, more salmonellae were found in the treated birds than in the control birds both on the farm and after processing. These data confirm that when salmonellae levels were controlled in the hatchery, a significant reduction in the salmonellae was found on processed broiler carcasses treated with MSC and that this reduction in salmonellae was carried through processing to the final processed carcass, thus potentially reducing consumer exposure to salmonellae.

Animals↗
PubMed1999

Mucosal competitive exclusion to reduce Salmonella in swine.

A mucosal competitive exclusion culture has been shown to reduce or eliminate Salmonella spp. in poultry. Using similar techniques, a mucosal competitive exclusion culture from swine (MCES) was produced from the cecum of a 6-week-old pig. Suckling pigs were inoculated with 5 ml of MCES by oral gavage within 6 h postfarrowing (PF) and again at 24 h PE All pigs were challenged with 10(3) CFU of Salmonella Choleraesuis at 48 h PF by intranasal instillation, including pigs from two sows that had not been given MCES. Clinical signs and rectal swabs were monitored daily, and pigs were allowed to suckle throughout the experiment. All pigs underwent necropsy on day 7 PF, and presence of Salmonella was determined in both qualitative (10 tissues) and quantitative (two tissues) samples. Clinical signs were inapparent in all pigs throughout the experiment. Recovery of Salmonella from rectal swabs was variable. However, 28% of the gut tissues were positive from the MCES-treated pigs versus 79% from the control pigs. A 2- to 5-log10 reduction of Salmonella in the cecal contents or ileocolic junction was observed in the MCES-treated pigs when compared with the controls. These data indicate that use of MCES may be a useful approach for control of Salmonella.

Animals↗
PubMed1998

Effect of yeast-supplemented feed on Salmonella and Campylobacter populations in broilers.

The effect of the yeast, Saccharomyces boulardii, on experimental cecal colonization of broilers with Salmonella typhimurium and Campylobacter jejuni was investigated. Duplicate pens of broiler chicks were given ad libitum access to a standard feed supplemented with no yeast (control), or 1 g (1x), or 100 g (100x) dried S. boulardii/kg feed. All chicks except negative controls were challenged on Day 4 with 3.2 x 10(8) cfu S. typhimurium and 6.5 x 10(8) cfu C. jejuni by oral gavage. After 3 wk, the broilers were euthanatized and ceca were aseptically removed and analyzed for Salmonella and Campylobacter. Frequency of Salmonella colonization was significantly (P < 0.05) reduced due to yeast treatment. Of the positive control birds, 70% were colonized with Salmonella; whereas only 20 and 5% of the 1x and 100x yeast-treated birds were colonized. Mean number of Salmonella per gram of ceca and contents were log 1.64, 0.35, and 0.15, respectively, for the control, 1x, and 100x yeast-treated birds. Campylobacter colonization was not significantly affected by yeast treatment. Similar results were obtained from a second trial conducted in larger isolation floor pens.

Animal Feed↗
PubMed1998

Microbial food borne pathogens. Campylobacter jejuni.

Campylobacter jejuni is the most common food borne bacterial pathogen and leading cause of food borne disease in humans in the United States and other industrialized nations. Approximately four million cases of human campylobacteriosis occur each year in the United States. Although the majority of cases consist of limited diarrheal illness, severe sequelae can affect a small portion of patients with campylobacteriosis that may include reactive arthritis and Guillain-Barré syndrome. Animal reservoirs primarily include poultry (C. jejuni) and swine (C. coli). Pathogen reduction during poultry processing and safe handling of raw poultry in the kitchen are needed to prevent illness.

Animals↗
PubMed1997

Effect of cloacal plugging on microbial recovery from partially processed broilers.

Experiments were performed to test the contribution of bacteria contained in the intestinal tract of broilers at the beginning of processing to counts on the exterior of modified New York-dressed carcasses. Thirty-two birds were processed for each of seven replications. Within each replication, batches of four birds were electrocuted, scalded, and picked, with batches alternating between treatment and control groups. Treated birds were cloacally plugged with rayon fiber tampons prior to electrocution to prevent escape of intestinal contents during scalding and picking. Control birds were processed in the same manner, except that cloacal plugs were inserted immediately after defeathering to reduce escape of intestinal contents during sampling. Gram-negative enteric bacteria and Campylobacter spp. were enumerated on carcasses by whole carcass rinse procedure and in cecal contents. Counts were converted to log10 and subjected to analysis of variance. Cecal levels of Gram-negative enterics were significantly higher for plugged birds, but there was not a significant difference between levels of cecal Campylobacter spp. between treatment groups. Plugging before electrocution resulted in significantly lower levels (2.5 vs 3.0 log10 cfu/mL) of Campylobacter spp. and Gram-negative enteric bacteria (3.0 vs 3.4 log10 cfu/mL) in carcass rinses of treatment birds than in those of controls. All carcasses were positive for Gram-negative enterics. Cloacal plugging resulted in significantly lower incidence of Campylobacter spp. carcass contamination as determined by chi-square. Intestinal carriage of both campylobacters and Gram-negative enteric bacteria appears to influence the microbial quality of the carcass during processing.

Analysis of Variance↗
PubMed1997

Relationship between aerobic bacteria, salmonellae and Campylobacter on broiler carcasses.

Broiler carcasses were removed from commercial processing lines immediately after defeathering, before chilling, and after chilling to determine whether any relationship exists between aerobic bacteria and the human enteropathogens salmonellae and Campylobacter. In two experiments, a whole carcass rinse procedure was used to sample 30 carcasses after defeathering, 90 carcasses before chilling, and 90 carcasses after chilling, for a total of 210 different carcasses. Aerobic bacteria and Campylobacter spp. were enumerated and the incidence of salmonellae was determined. Salmonellae and Campylobacter incidences were 20 and 94%, respectively, for all carcasses sampled. After picking, neither salmonellae-positive nor Campylobacter-positive carcasses had mean aerobic most probable number (MPN) values that were different from carcasses negative for those organisms. Immediately before chilling, aerobic and Campylobacter counts were 7.12 and 5.33 log10 cfu per carcass, respectively. Immersion chilling reduced aerobic counts by approximately 1.8 log and Campylobacter by 1.5 log, with no change in salmonellae-positive carcasses. There was no difference in aerobic or Campylobacter counts between carcasses that were positive or negative for salmonellae at any of the sampling locations, nor was any correlation found between levels of aerobic organisms and Campylobacter. Carcasses with aerobic counts above the mean or more than one standard deviation above the mean also failed to show any correlation. Discriminant analysis indicated error rates as high as 50% when numbers of aerobic bacteria were used to predict incidence of salmonellae or Campylobacter on individual carcasses. Aerobic bacteria are not suitable as index organisms for salmonellae or Campylobacter on broiler carcasses.

Animals↗
PubMed1997

Yeast treatment to reduce Salmonella and Campylobacter populations associated with broiler chickens subjected to transport stress.

The prevalence of Campylobacter and Salmonella on retail poultry carcasses remains a significant public health concern. The stresses associated with transporting poultry prior to slaughter have been shown to increase pathogen populations both in the intestinal tract and on the carcass exterior. The yeast, Saccharomyces boulardii, was evaluated for its ability to reduce populations of Salmonella and Campylobacter in broiler chickens subjected to transport stress. Chicks, inoculated with individual strains of Salmonella and Campylobacter were held for 6 wk and then divided into two groups with half of the chickens receiving 10% dried yeast in the feed for 60 h. The birds were then caged and transported to simulate commercial conditions. After euthanatizing the birds, the ceca were aseptically removed and analyzed for Salmonella and Campylobacter. With no yeast treatment, transport stress caused the Salmonella colonization frequency to increase more than fivefold, from 3.3 to 16.7%. Yeast treatment significantly reduced the frequency of Salmonella colonization to lower than prestress levels, as no Salmonella were recovered from the ceca of these birds (P < 0.05). Similar results were obtained from birds challenged with a mixture of Salmonella and Campylobacter strains. Before transport, 53.3% of these chickens were positive for Salmonella. Transport stress increased the colonization rate to 67.5% in control birds, whereas the colonization of yeast-treated chickens decreased to 40% (P < 0.05). Frequency of Campylobacter isolation from the ceca was not affected by treatment, but Campylobacter populations present in the ceca were significantly reduced in the mixed strain trial (P < 0.05).

Analysis of Variance↗
PubMed1995

Campylobacter spp. in broilers on the farm and after transport.

Colonization of the ceca and contamination on carcasses of chickens by Campylobacter spp. was investigated. Samples were taken on the farm and after transport and holding. In the first set of experiments, 20 chickens, obtained from each of 10 broiler farms, were collected from houses containing 6- to 7-wk-old birds. Half of the birds were slaughtered at the farm; the other half were transported (10 birds per chicken coop) to a holding facility and killed within 16 to 18 h. The levels of Campylobacter spp. on the carcass and in the ceca were assessed. Ceca from birds in 9 of the 10 farms sampled were positive for Campylobacter spp. Colonization levels ranged from 10(4.11) to 10(7.28) cfu Campylobacter spp./g cecal matter, except on one farm, where the organism was not isolated. The mean count on the farm was 10(5.44) cfu Campylobacter spp./g cecal material, and after transport the mean was 10(6.15) cfu/g. Significant increases (P = .0085) in levels of Campylobacter spp. on the chicken carcasses occurred after transport. Levels of Campylobacter spp. enumerated from unprocessed chicken carcasses after transport averaged 10(7.11) per carcass, up from an average of 10(3.66) cfu per carcass of the farm. To further verify this observation, field trials were conducted to assess levels on carcasses before and after commercial transport. Employing five farms and 200 6-wk-old chickens, the above observations were confirmed: prior to transport 12.1% of the chickens harbored an average of 10(2.71) cfu per carcass, but after transport 56.0% of the chicken exteriors harbored an average of 10(5.15) cfu per carcass. The results of this study indicate that transport and holding prior to processing contributes to the Campylobacter spp. of > 10(4) cfu normally found on processed poultry carcasses.

Analysis of Variance↗
PubMed1994

Mucosal competitive exclusion to diminish colonization of chickens by Campylobacter jejuni.

Mucosal competitive exclusion flora (MCE) and length of MCE culture storage were studied to determine their influence upon colonization of Campylobacter jejuni in chickens. Day-of-hatch broiler chicks, held in isolation units, were treated with MCE or were left untreated. Thirty to 48 h later, groups of chicks were challenged with serial dilutions of C. jejuni (Strain A74/C). Single challenge doses and treatments were administered to chickens within each isolation unit. After 5 d, chicks were killed and levels of the organism in cecal materials were enumerated. Effective MCE was held at -80 C in 15% glycerol for 3 to 9 mo, and efficacy in inhibiting C. jejuni colonization of fresh and stored MCE cultures was compared. Colonization dose-50% (CD50%; dose needed to colonize one-half of the challenged chicks) and colonization quotients (CQ; log10 colony-forming unit geometric means per gram cecal materials) were determined. Data indicated that in three of five trials a significant reduction (P < .02) in CQ was observed in groups of chicks provided fresh MCE as compared with the control groups. Generally, efficacy of MCE treatment decreased with storage of the cultures. This study defines methods for production of MCE and the advantages and limitations of MCE intervention for C. jejuni colonization in chickens.

Animals↗
PubMed1993

Role of Campylobacter jejuni flagella as colonization factors for three-day-old chicks: analysis with flagellar mutants.

Campylobacter jejuni, an important cause of human gastrointestinal infection, is a major food-borne pathogen in the United States and worldwide. Since poultry becomes colonized and/or contaminated during the early stages of production and is a major food-borne source for this organism, we studied the role of C. jejuni flagella on the ability of the bacterium to colonize the chicken gastrointestinal tract. Three-day-old chicks were orally challenged with a motile wild-type strain of C. jejuni IN9 or with flagellar mutants created from IN9 by disrupting the flagellin genes with a kanamycin resistance cassette by using shuttle mutagenesis (A. Labigne-Roussel, P. Courcoux, and L. Tompkins, J. Bacteriol. 170:1704-1708, 1988). One mutant, IN9-N3, lacked flagella and was nonmotile. The other, IN9-N7, produced a truncated flagellum and was partially motile. Three-day-old chicks were orally challenged with different doses of the wild-type strain and the two mutants. At challenge doses ranging from 3.0 x 10(4) to 6.6 x 10(8) CFU per chick, only the fully motile, wild-type strain colonized the chick ceca. Our results show that intact and motile flagella are important colonization factors for C. jejuni in chicks.

Animals↗
PubMed1993

Two-step mucosal competitive exclusion flora treatment to diminish salmonellae in commercial broiler chickens.

There is a need to control the intestinal colonization of broiler chickens by salmonellae in order to reduce the contamination of poultry products. A two-step treatment of broiler chicks with a mucosal competitive exclusion culture (MCE) was tested, in which the MCE was first sprayed on chicks in the hatchery followed by administration in the first drinking water. Three commercial flocks were treated and compared with parallel, untreated control flocks. Customary husbandry practices were employed. Environmental, hatchery, skin with feathers, and cecal samples were analyzed at 3 and 7 wk for the presence of salmonellae. Carcass rinse samples of fully processed birds were analyzed similarly. The results indicated that initial feed, water, and litter contamination was at a low frequency (< 10%). Eggshell fragments and chick paper pads were frequently contaminated (> 50%). After 3 wk growth, contamination of litter, skin with feathers, and ceca were significantly (P < .05) reduced in treated flocks as compared with control flocks. Salmonellae prevalence in ceca and in processed carcass rinses was also significantly (P < .05) reduced from 41% in control flocks to 10% in treated flocks. The study showed that treatment of chickens in a commercial setting with MCE cultures can serve as a useful means to reduce salmonellae contamination.

Animals↗
PubMed1991

Simultaneous colonization of Campylobacter jejuni and Salmonella typhimurium in day-old chicks.

Day-old chicks were challenged with Campylobacter jejuni or Salmonella typhimurium or both to assess the influence of these two bacteria upon the colonization of one another. Median colonization dose (CD50), a measure indicating the number of organisms required to colonize one-half of the challenged chickens, was used to assess the influence of these organisms upon the colonization of one another. Chicks were gavaged with serial dilutions of 1) C. jejuni, 2) S. typhimurium, 3) dilutions of C. jejuni and a fixed level of S. typhimurium, or 4) dilutions of S. typhimurium and a fixed level of C. jejuni. Six days postchallenge, cecal contents were quantitatively assayed for the challenge organisms. Birds challenged with only C. jejuni or birds challenged with both C. jejuni and S. typhimurium had a CD50 of 120 C. jejuni cells. The CD50 values for S. typhimurium alone (48 cells) and S. typhimurium simultaneously colonized with C. jejuni (180 cells) were not significantly different (P less than .05). The colonization levels of either organism were generally correlated with the challenge dose and ranged up to 63 million cells per gram. It was concluded that the CD50 for both C. jejuni and S. typhimurium in 24-h-old chicks were similar, and the presence of one of these particular co-colonizers does not influence the CD50 of the other.

Animals↗
PubMed1991

Comparative study of colonizing and noncolonizing Campylobacter jejuni.

Campylobacter jejuni A74/O and A74/C are congenic strains. An oral dose of 10(5) organisms of strain A74/C colonizes chicken intestines. Strain A74/O, from which A74/C is derived, does not colonize the chicken intestines with an oral dose of 10(5) organisms. In this study, the congenic bacteria were compared to identify possible colonization mechanisms. Differences were not observed in plasmid content or by HindIII, Pst I, Acc I, HincII, Ava I, Ava II, Xba I, and BamHI restriction enzyme digestion of total DNA. Transmission electron microscopy of negatively stained samples revealed no differences between the strains. Sections of cecal tissue from nonfed day-of-hatch chicks were cultured with each strain for 2 hours and then examined by light and electron microscopy. Both strains caused necrosis of villus epithelial cells. Immunofluorescent or silver staining revealed strain A74/C located deep in numerous epithelial crypts, but strain A74/O only was present in one sample mixed with sloughed necrotic cells. Similarly, organisms were detected by transmission electron microscopy deep in crypts in tissues cultured with A74/C, but not A74/O. Cells of A74/C detected in crypts did not appear to associate with epithelial cells. The strains did not differ in chemotactic behavior to mucin or fucose.

Animals↗
PubMed1990

Fifty percent colonization dose for Salmonella typhimurium administered orally and intracloacally to young broiler chicks.

One and 3-day-old chicks were challenged with varying levels of Salmonella typhimurium by gavage or intracloacal administration. Chicks were killed 5 days postchallenge, and ceca were analyzed for the presence of S. typhimurium. About 100-fold fewer S. typhimurium cells were required to colonize young chicks by the intracloacal route than by gavage. It was hypothesized that the low pH of the upper gastrointestinal tract contributes to the higher levels of Salmonella required to colonize young chicks via the oral route. The pH measurements in the gizzard of freshly killed chicks were variable, but most were low enough to be bactericidal. Presence of salmonellae in the hatchery environment and the low level of cells (2 cfu) required to colonize young chicks via cloacal challenge suggest that day-of-hatch chicks may be at a high colonization risk from salmonellae in the hatchery.

Administration, Oral↗
PubMed1988

Response of Campylobacter jejuni to combinations of ferrous sulphate and cadmium chloride.

On Mueller Hinton (MH) agar, Campylobacter jejuni showed 20.0 and 30.9 mm zones of inhibition surrounding discs impregnated with 2.5 and 20 micrograms CdCl2 respectively. The minimal inhibitory concentration (MIC) ranged from 0.64 to 3.2 micrograms CdCl2/ml of MH agar for four C. jejuni strains. In the presence of 23 micrograms FeSO4/ml of MH the MIC increased to a range of 1.5-5.4 micrograms CdCl2/ml of MH. Moreover, the numbers of colonies present on MH supplemented with FeSO4 were greater than on MH without iron. The growth response of C. jejuni in the presence of 0.025% (w/v) FeSO4 in MH broth was increased about 10,000 fold in three of four strains when compared with the growth in unsupplemented MH broth. Zones of inhibition surrounding 20 micrograms discs of CdCl, were 50.6 and 24.4 mm on MH and Campy-BAP media respectively, with cells grown on MH. These results suggest that the blood-containing medium 'neutralized' the biocidal influence of the CdCl2. In comparison, C. jejuni inoculum from fluid thioglycollate (FT) medium showed smaller zones of inhibition. These decreased from 34.9 mm on MH agar to 19.6 mm on Campy-BAP agar, suggesting that components in the FT growth medium ameliorated the toxic influence of CdCl2. Atomic absorption spectroscopy analysis indicated mean values (mg/100 g dry weight) of selected metals bound by C. jejuni as: Cu, 10.4; Mg, 146; Na, 2385; Fe, 45.1; Zn, 13.0; and K, 172.

Animals↗