Biomedical subjects

N A Cox

Publications and source records attributed to N A Cox.

At least 55 records · Page 3Linked to original sources

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↗

PubMed1996

Effect of hatching cabinet sanitation treatments on Salmonella cross-contamination and hatchability of broiler eggs.

Four trials were conducted to evaluate the efficacy of hatcher air sanitation utilizing ultraviolet light (UV), ozone, or hydrogen peroxide on bacterial populations, the spread of Salmonella, and hatchability of broiler eggs. The UV light (254 nm, 146 mu W/s) and ozone (0.2 or 0.4 ppm) treatments were continuously applied through the last 3 d of hatch, the hydrogen peroxide treatment (2.5%) was administered 1 or 2 min of each 10 min at rates of 500 or 100 mL/h. Hatchability was not significantly reduced by sanitizing treatments when compared with the untreated control (94 vs 95.6%). As compared to controls, all sanitizing treatments reduced 75 to 99% of the total bacteria, Enterobacteriaceae, and Salmonella in the hatching cabinet air samples. The use of hydrogen peroxide resulted in greater reduction of bacteria than ozone or UV light. Only hydrogen peroxide significantly reduced Salmonella levels on eggshell fragments. Significant reductions in the number of Salmonella-positive chicks occurred using the ozone and hydrogen peroxide treatments. Hydrogen peroxide significantly reduced the magnitude of Salmonella colonization in chicken ceca. These trials demonstrated that the spread of bacteria can be effectively reduced in the hatching cabinet by air sanitization using UV light, ozone, and hydrogen peroxide. The potential to reduce bacterial cross contamination in the hatcher is achievable without depressing hatchability.

Air Pollution, Indoor↗

PubMed1996

The effect of temperature mishandling at various times during storage on detection of temperature abuse of fresh broiler chicken carcasses.

Experiments were conducted to determine the effect that temperature mishandling at various times during storage has on detection of temperature abuse of fresh broiler chicken carcasses using populations of mesophilic and coliform bacteria as indicators of abuse. Forty-five broiler carcasses were used in each of three independent trials. Five carcasses were analyzed at day of collection (Treatment 0 control). Five carcasses, on each day of the next 7 d (Treatments 1 to 7) were temperature-abused for 12 h at 25 C, stored at 3 C until Day 9, and then sampled. The five remaining carcasses were stored at 3 C and sampled on Day 9 (Treatment 8 control). Carcasses were sampled using a whole carcass rinse procedure and assayed for aerobic plate counts (APC), total coliform counts (TCC), impedance detection times (DT), and impedance coliform detection times (DTCM). Although significant differences were noted using all four microbiological methods, temperature abuse at different times during storage had no consistent effect on populations of mesophilic or coliform bacteria; therefore, temperature abuse determinations may be conducted without regard to the day on which the carcasses were subjected to elevated temperatures.

Animals↗

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↗

PubMed1995

Spoilage bacteria of fresh broiler chicken carcasses.

Studies were conducted to identify the bacteria responsible for spoilage of fresh broiler chicken carcasses and to characterize the off-odors these bacteria produce. Broiler carcasses were collected from processing plants in the northeast Georgia area, the southeastern U.S., Arkansas, California, and North Carolina. The carcasses were allowed to spoil under controlled conditions at 3 C and spoilage bacteria were isolated. Each spoilage bacterium was separately inoculated into a sterile chicken skin medium, incubated at 25 C for 48 h, and subjectively evaluated for odor. The bacteria isolated from spoiled carcasses that consistently produced off-odors in the chicken skin medium, regardless of the geographical location from which the chickens were obtained, were Shewanella putrefaciens A, B, and D, Pseudomonas fluorescens A, B, and D, and Pseudomonas fragi. These bacteria produced off-odors that resembled "sulfur", "dishrag", "ammonia", "wet dog", "skunk", "dirty socks", "rancid fish", "unspecified bad odor", or a sweet smell resembling "canned corn". Odors produced by the spoilage bacteria were varied; however, odors most associated with spoiled poultry, such as "dishraggy" odors, were produced by the bacteria that were most consistently isolated, such as S. putrefaciens and the pseudomonads.

Acinetobacter↗

PubMed1994

Effect of freezing on the recovery of mesophilic bacteria from temperature-abused broiler chicken carcasses.

The effects of freezing on the recovery of mesophilic bacteria from broiler chicken carcasses were determined. Fifty fresh broiler carcasses were used in each of three independent trials. Ten carcasses were sampled at time of collection (Treatment 1: Day 0 control). The other 40 carcasses were sampled at Day 7 following one of four additional treatments with 10 carcasses each: held at 3 C (Treatment 2: 7-d control), frozen and then held at 3 C (Treatment 3: frozen control), temperature abused at 25 C for 12 h and held at 3 C (Treatment 4: temperature abused), and temperature abused at 25 C for 12 h, frozen, and held at 3 C (Treatment 5: temperature abused and frozen). Carcasses were sampled by rinsing, and total plate counts (TPC) expressed as log10 colony-forming units per milliliter and impedance detection times (DT) in hours were determined using incubation temperatures of 42 and 43 C, respectively. Results for TPC for Treatments 1 to 5 were 3.89, 3.52, 2.86, 6.53, and 5.57 log10 cfu/mL, respectively. Results for DT for Treatments 1 to 5 were 5.41, 6.50, 7.10, 2.55, and 3.42 log10 cfu/mL, respectively. Freezing reduced the ability to detect temperature abuse because of a significant reduction in the number of mesophiles recovered using either microbiological technique. Freezing appears to decrease, but may not completely eliminate, the ability of selective incubation to detect temperature abuse.

Animals↗

PubMed1994

The effect of incubation temperature on recovery of mesophilic bacteria from broiler chicken carcasses subjected to temperature abuse.

The optimum temperature to recover mesophilic organisms from temperature-abused broiler chicken carcasses was determined. Twenty broiler carcasses were collected from a commercial processing plant in each of three trials. Ten carcasses were sampled immediately (Day 0 control); 8 carcasses were sampled after holding at 3 C for 3 d, temperature abusing at 25 C for 12 h, and holding them at 3 C for an additional 3 d (temperature abused); and the remaining 2 carcasses were sampled after holding at 3 C for 7 d (Day 7 control). Whole carcass rinses were analyzed using total aerobic plate counts (TPC) and impedimetric detection times (DT) at incubation temperatures of 41, 42, 43, and 44 C. Total plate counts decreased (P < .05) and DT increased (P < .05), at all incubation temperatures tested, for carcasses held under refrigeration (Day 7 control). This demonstrates that mesophilic bacteria, rather than psychrotrophic bacteria, are being enumerated, because psychrotrophs increase on chicken skin upon cold storage. Total plate count was greater (P < .05) and DT was significantly lower for temperature-abused vs Day 7 control birds (5.7 vs 3.6 log10 cfu/mL and 3.7 vs 6.5 h), respectively. These results indicate that temperature-abused carcasses can be microbiologically distinguished from nonabused controls at all incubation temperatures tested. Recovery of mesophiles was optimal at 41 and 42 C for TPC and 41, 42, and 43 C for DT. Because there were no differences between DT at 41, 42, and 43 C, and because 42 C has been successfully used in the past, either 42 C or 43 C can be used when determining DT.

Animals↗

PubMed1994

Hatchery-acquired salmonellae in broiler chicks.

Hatchery contamination can result in exposure of newly hatched chicks to salmonellae at a time when they are most susceptible to colonization of their intestinal tract. Eggshell fragments, external rinses, and intestinal tracts from day-of-hatch chicks were sampled for salmonellae contamination. Chicks from the same hatching trays were then put in isolators or floor pens and fed a pelleted corn-soybean ration for 1 wk before external rinses and ceca from each chick were sampled for salmonellae. About 17% of eggshell, 21% of chick rinses, and 5% of intestines sampled at Day 0 were positive for salmonellae. No differences were observed between broiler hatcheries, but significant differences were seen between replications within hatching cabinets. Results from this study suggest a correlation between hatchery-acquired salmonellae and the production of potential seeder birds. No differences between eggshell and chick rinse samples were found (correlation = .81); therefore, eggshells are recommended as the best sample to determine hatchery salmonellae contamination.

Air Microbiology↗

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↗

PubMed1993

Location of Salmonella typhimurium during incubation and hatching of inoculated eggs.

Location of Salmonella during hatching of broiler chicks was studied in three experiments. Unincubated, fertile hatching eggs heated to 42 C were inoculated by immersion for 15 min in a 16 C physiological saline solution containing approximately 1 x 10(5) cfu/mL of a nalidixic acid-resistant strain of Salmonella typhimurium. All eggs were sanitized externally by wiping with a paper towel wet with 70% ethanol. When incubating eggs were transferred to a hatcher, each was placed in a closed paper bag to minimize cross-contamination. Unhatched eggs were sampled by cutting away the shell over the air cell, sanitizing the inner air cell membrane with 70% ethanol, and removing the contents through the membrane. Shells and membranes were crushed and mixed in 10 mL buffered peptone (BP). Yolks were dissected out, dipped in 70% ethanol, and mixed with 10 mL BP. Embryos or chicks and all surrounding fluid were rinsed in 100 mL BP. A total of 172 eggs was sampled. Shells and membranes were 100% Salmonella-positive 30 min after inoculation, but only 38% were positive after 17 to 21 days of incubation. No chick rinses were positive before pipping, but 15% were positive after pipping. Yolk samples were 2% positive before pipping versus 8% after pipping. A majority of chicks hatching from positive shells and membranes were Salmonella-negative.

Animals↗

PubMed1992

The effect of air scrubbing on moisture pickup, aerobic plate counts, Enterobacteriaceae, and the incidence of salmonellae on artificially inoculated broiler carcasses.

Processed broiler carcasses were subjected to diffused air at 158.6 kPa (air scrubbing) in tap water to evaluate the potential of this treatment for improving the microbiological quality of read-to-cook poultry. Carcasses were inoculated with a marker strain of Salmonella typhimurium 5 min before treatment. The carcasses were removed after 30 min and sampled for aerobic plate counts (APC), Enterobacteriaceae (ENT) counts, for the presence of the marker organism, or for moisture pickup. The S. typhimurium were recovered from 32 of 40 control carcasses (water only), but from only 9 of 40 air-scrubbed samples. When carcasses were inoculated with fewer than 150 cells of the marker organism, air scrubbing was more effective in reducing the incidence of salmonellae (2 of 20 positive) than when levels were in excess of 150 cells (7 of 20 positive). A similar pattern was manifested with the water-rinsed carcasses rinsed without air injection (below 150, 12 of 20; above 150, 20 of 20). No significant differences were found in the APC and ENT counts. Moisture pickup was adversely affected by air scrubbing; control carcasses had a moisture pickup of 5.8%, whereas, air-scrubbed carcasses had a moisture pickup of 13.9%.

Analysis of Variance↗

PubMed1992

A rapid method for the determination of temperature abuse of fresh broiler chicken.

Ready-to-cook broiler chicken carcasses were obtained immediately postchill from a commercial processing plant. A control group was held at 4 C for 10 days. Test groups were held at 4 C for 2 days, temperature abused at 10, 15, or 20 C for 0, 1, 2, 4, 6, 8, 12, or 24 h, and then held at 4 C for an additional 4 days. Both control and test birds were sampled using whole carcass rinse techniques and bacteria enumerated using impedance detection times (DT) and total plate count (TPC) techniques at incubation temperatures of 18 and 42 C. The DT and TPC showed a significant increase (P less than .05) in the number of organisms recovered at 18 C but did not show a significant increase (P less than .05) in organisms recovered at 42 C when carcasses were held at 4 C continuously for up to 10 days. Carcasses that were temperature abused at 10 C for up to 24 h were not significantly different (P less than .05) from the unabused controls, using either DT or TPC, following incubation at 18 and 42 C. At an incubation temperature of 18 C, carcasses abused at 15 or 20 C had significantly more growth of bacteria than controls at 1, 6, 12, and 24 h and 4, 8, and 12 h as determined by DT and at 6, 12, and 24 h and 1, 2, 4, 8, and 12 h, respectively, as determined by TPC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Research note: in ovo administration of a competitive exclusion culture treatment to broiler embryos.

Exposure of chicks to salmonellae in the hatchery and hatchery environment limits the effectiveness of a competitive exclusion (CE) culture treatment. Therefore, in an attempt to apply treatment before chicks are exposed to salmonellae, the CE culture was introduced in ovo to unhatched embryos. An undefined, anaerobically grown CE culture, derived from cecal contents of healthy adult chickens, was diluted 1:1,000 or 1:1,000,000 and inoculated either into the air cell or beneath the inner air cell membrane of 17-day-old incubating hatching eggs. The treated chicks were more resistant than untreated chicks to varying challenge levels of Salmonella typhimurium, indicating that it may be possible to initiate protection of chicks to salmonellae challenge prior to hatching into a contaminated environment.

Animals↗

PubMed1991

Extent of salmonellae contamination in breeder hatcheries.

Egg fragments, paper pads from chick boxes, and fluff samples were obtained from six commercial broiler breeder hatcheries and analyzed for the presence and level of salmonellae. Overall, 42 of 380 samples (11.1%) from those hatcheries were contaminated with salmonellae. Salmonellae organisms were detected in 22 of 145 (15.2%), 5 of 100 (4.6%), and 15 of 125 (12%) samples of egg fragments, fluff, and paper pads, respectively. The percentage salmonellae-positive samples from each of the six hatcheries were 1.3, 5.0, 22.5, 11.4, 36.0, and 4.3% respectively. Of the 140 samples randomly selected for enumeration, salmonellae were found in 11 samples. Four of these 11 samples had greater than 10(3) salmonellae per sample, 3 others had greater than 10(2) but less than 10(3), and the remaining 4 had less than 10(2). Salmonella serotypes isolated were S. berta, S. california, S. give, S. hadar, S. mbandaka, S. senftenberg, and S. typhimurium, all of which have previously been isolated from poultry. The incidence and extent of salmonellae-positive samples found in the breeder hatcheries were much less than that previously found in broiler hatcheries. Many factors contribute to the lower incidence and level of salmonellae found in the breeder hatcheries; however both the breeder and broiler hatcheries present critical control points in the prevention of salmonellae contamination during commercial poultry production. The cycle of salmonellae contamination will not likely be broken until contamination at these critical points is eliminated.

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

Methods for inoculation and recovery of Salmonella from chicken eggs.

Various methods of applying inoculum and recovering low numbers of artificially inoculated Salmonella typhimurium on eggs were evaluated. Inoculation methods tested were suspending cells in 1) .85% saline; 2) 1% peptone; 3) sterile chicken fecal paste; or 4) a 1:10 dilution of chicken feces in .85% saline. Sampling methods tested were 1) shell and membrane massage; and 2) mortar and pestle grinding of shells and membranes. The method that yielded the best recovery of low numbers of Salmonella was as follows: 1) apply cell suspension in 1% peptone to egg; 2) sample egg by a hand crush and massage of shell and membranes in 50 mL of buffered peptone; 3) incubate shell and membranes in buffered peptone overnight and then plate onto selective agar. Methods that did not improve sensitivity of recovery included varying the inoculum drying time, addition of FeSO4 or Cleland's reagent to the recovery medium, and varying the temperature of the inoculum to affect penetration.

Animals↗

PubMed1991

Effect of fructooligosaccharide on Salmonella colonization of the chicken intestine.

The influence of fructooligosaccharide (FOS) on the ability of Salmonella typhimurium to grow and colonize the gut of chickens was investigated. In vitro studies showed that Salmonella did not grow when FOS was the sole carbon source. When FOS was fed to chicks at the .375% level, little influence on Salmonella colonization was observed. At the .75% level, 12% fewer FOS-fed birds were colonized with Salmonella compared with control birds. When chicks given a partially protective competitive exclusion (CE) culture were fed diets supplemented with .75% FOS, only 4 of 21 (19%) chickens challenged with 10(9) Salmonella cells on Day 7 became colonized as compared with 14 of 23 (61%) chickens given CE alone. When chickens were stressed by feed and water deprivation on Day 13 and challenged with 10(9) Salmonella on Day 14, 33 of 36 (92%) chickens fed a control diet were colonized compared with only 9 of 36 (25%) chickens fed a .75% FOS diet. Chickens treated with FOS had a fourfold reduction in the level of Salmonella present in the ceca. Feeding FOS in the diet of chickens may lead to a shift in the intestinal gut microflora, and under some circumstances may result in reduced susceptibility to Salmonella colonization.

Animal Feed↗