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Biomedical subjects

N A Cox

Publications and source records attributed to N A Cox.

At least 73 records · Page 4Linked to original sources
PubMed1990

Listeria monocytogenes colonization of broiler chickens.

In three trials, a total of 108 broiler chickens were unchallenged or challenged orally with either 10(2) or 10(6) cells of Listeria monocytogenes at 1, 14, or 35 days of age. The birds were kept in separate wire-floored brooders and growout batteries, fed unmedicated broiler-starter rations ad libitum, and killed 7 days postchallenge. The ceca, duodenum, spleen, liver (including gall bladder), and a cloacal swab were sampled from each bird and were analyzed for the presence of L. monocytogenes. In Trial 1, L. monocytogenes was recovered on all sampling days, but most frequently from birds challenged when 1 day old. In Trials 2 and 3, recovery was only from birds challenged at 1 day of age. The L. monocytogenes organism was not recovered from any uninoculated control birds. There was a dose-related colonization response (10(6) greater than 10(2]; and more recoveries were obtained from the ceca, spleen, and cloacal swabs than from the duodenum and liver.

Animals↗
PubMed1990

The presence of Yersinia enterocolitica and other Yersinia species on the carcasses of market broilers.

Sixty ready-to-cook broiler carcasses obtained from several local supermarkets were tested for the presence of Yersinia enterocolitica and other Yersinia species. In the present study, the authors used two enrichment broths, yeast-extract/rosebengal-bile oxalate sorbose (YER-BOS) and phosphate-buffered saline with a postenrichment KOH treatment (PBS-KOH), and two plating media, cefsulodin-irgasan-novobiocin (CIN) and pectin agar. Yersinia organisms were found on 34 of 60 carcasses (56.7%) and Y. enterocolitica, on 16 of 60 carcasses (26.7%). There was no significant difference between CIN and pectin agar; however, PBS-KOH yielded a significantly higher (P less than or equal to .05) detection rate than YER-BOS, regardless of the plating media used. In addition to Y. enterocolitica, Y. frederiksenii and Y. intermedia were also isolated from the market broilers. None of the Y. enterocolitica isolates were found to be presumptively virulent.

Animals↗
PubMed1990

Comparison of enrichment and plating media for isolation of Yersinia.

Yersinia enterocolitica (Serotypes 0:3 or 0:8), Yersinia frederiksenii, Yersinia kristensenii, or Yersinia intermedia along with 10(8) cells of each of three extraneous organisms (Escherichia coli, Enterobacter aerogenes, Pseudomonas fragi), all commonly found on market poultry, were inoculated into five enrichment media followed by streaking onto 11 plating media to determine the most-efficacious combinations for future surveys or assessment studies. For Yersinia enterocolitica (0:8), infrequent recoveries were made using yeast extract-rosebengal-bile oxalate sorbose broth and phosphate-buffered saline (4 C) followed by plating onto pectin, DNase-Tween 80 (polyoxyethylene sorbitan monooleate)-sorbitol, MacConkey-Tween 80, or cefsulodin-irgasan-novobiocin (CIN) agars. With Y. enterocolitica (0:3), recoveries were most frequently made using phosphate-buffered saline, sorbitol bile (incubated for 17 days) and yeast extract-rosebengal-bile oxalate sorbose broth followed by plating onto pectin, CIN, bismuth sulfite (Difco Laboratories, Detroit, MI), or modified Rimler-Shotts agar. For Y. frederiksenii, Y. kristensenii, and Y. intermedia, incubation in sorbitol bile for 17 days or in yeast extract-rosebengal-bile oxalate sorbose broth, followed by plating onto CIN, pectin, DNase-Tween/80-sorbitol, cellobiose-arginine-lysine agar, or MacConkey-Tween 80 agar yielded the most-frequent recoveries. Overall, the CIN and pectin agars performed best for the recovery of the Yersinia bacterium; the modified selenite broth and the bismuth-sulfite plating agars were unsatisfactory in the present study.

Animals↗
PubMed1990

A comparison of seven microbiological sampling procedures for hard-cooked eggs.

Seven microbiological sampling methods for hard-cooked eggs were evaluated and compared. Fresh eggs within 24 h of oviposition were cooked at 98 C for 22 min in water and then cooled in 31 C water. Eggs were dipped for 10 min in a physiological saline solution (.85% saline) 10 C cooler than the eggs and containing known numbers of bacteria. Eggs were then stored for 4 days at 6 C and sampled using one of seven rinse or blend procedures on whole eggs, shell, shelled egg contents, or shelled egg contents plus shell. Highest recoveries were made from the peeled egg plus shell rinse, shell rinse, whole egg blend, and shell blend. Lowest recoveries were found with the whole egg rinse, the peeled egg rinse, and the peeled egg blend. These results indicate that significant numbers of organisms are associated with the inner and outer shell surfaces as well as the egg contents surface (albumen). Satisfactory recoveries can be made with the peeled egg plus shell rinse or the whole egg blend. Whole egg rinsing of hard-cooked eggs does not appear to be satisfactory.

Bacteriological Techniques↗
PubMed1990

Presence and impact of Salmonella contamination in commercial broiler hatcheries.

Egg fragments from hatching trays, swabs of belting material, and paper pads from three broiler hatcheries were sampled for the presence and level of salmonellae. Salmonella serotypes were recovered from 71, 80, and 74% of the egg fragments, belting material, and paper pads, respectively. Overall, salmonellae were found in 75, 91, and 67% of the samples taken at Hatchery 1,2, and 3, respectively. Thirty-eight of 40 randomly selected samples contained greater than 10(3) salmonellae cells per sample. All of the Salmonella serotypes encountered in the present study had previously been isolated from poultry. The presence and persistence of salmonellae contamination in the hatchery suggests that the vulnerable day-of-hatch chick may be at a greater colonization risk in the hatchery than during grow-out. Contamination and penetration of the shell of hatching eggs may constitute the most important link (or critical control point) in the transmission of salmonellae to young birds and eventually the consumer. An effective intervention method may have to be employed at this point to break the transmission link and significantly impact the overall problem of Salmonella colonization in poultry.

Animal Husbandry↗
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

Salmonella methodology update.

This paper reviews the numerous research studies carried out at Richard Russell Agricultural Research Center over the past 10 to 15 yr that ultimately led to the Center's present methods for the isolation of Salmonella from processed broiler carcasses and poultry feed. In addition, the newer technologies that have recently evolved are discussed in complete detail. Included in these discussions are the advantages and disadvantages of the various technologies along with recommendations for making them more useful to the practicing food or poultry microbiologist.

Animals↗
PubMed1985

Recovery of inoculated Salmonella from poultry feed containing furazolidone.

It was determined that the presence of furazolidone, a common feed additive, prevented detection of Salmonella in feed samples. Artificially inoculated Salmonella were not recovered from feed samples containing furazolidone when buffered peptone broth (BP) was used as an enrichment medium, but Salmonella were recovered from all feed samples containing furazolidone when thiol broth was used as a substitute for BP.

Animal Feed↗
PubMed1983

Heating by microwave, hot air, and flowing steam to eliminate inoculated Salmonella from poultry feed.

Poultry feed samples (mash) obtained from a commercial mill were inoculated with either 100 or 5,000 cells/g of a marker strain of Salmonella montevideo. Samples (125 g) were then placed in a microwave oven at power settings of 1.5 or 2.0 kW for 60, 90, or 120 sec; a hot air oven at 99 C (210 F) or 110 C (230 F) for 15, 30, 45, or 60 min; or a flowing steam chamber for 1, 5, 10, or 20 min. Temperature, moisture, and presence of the inoculated S. montevideo were determined in all samples before and after treatment. Feed samples placed in the microwave oven reached a maximum temperature of 186 C (367 F) and had a final moisture content as low as .8%. About 25% of the samples inoculated with 100 cells/g and about 40% of those inoculated with 5,000 cells/g remained positive after treatment. In the hot air oven, feed reached a maximum temperature of 93 C (200 F) with a moisture level after heating of about 4%. Salmonellae were recovered from 35 and 60% of the low and high inoculum level samples, respectively. In flowing steam, maximum feed temperature was 90 C (194 F) with a final moisture level of 15%. After 1, 5, 10, and 20 min of flowing steam, 100, 90, 60, and 0% of the samples were found to contain salmonellae, respectively. All treatments occasionally eliminated salmonellae from the samples, but results were inconsistent and unpredictable.

Air↗
PubMed1983

Salmonella and other Enterobacteriaceae found in commercial poultry feed.

Poultry feed (mash and pelleted) and meat and bone meal samples were collected from commercial mills. All samples were analyzed for Enterobacteriaceae count (ENT) and Salmonella. The genus and species of the various Enterobacteriaceae present were also determined. The average ENT for mash, pelleted, and meal samples was log 4.1, .8, and 1.8/g, respectively. Enterobacteriaceae were present in 100, 60, and 92% and Salmonella in 58, 0, and 92% of the mash, pelleted, and meal samples, respectively. Overall, the Enterobacteriaceae most frequently isolated from all samples were Enterobacter agglomerans, Enterobacter cloacae, and Klebsiella pneumoniae. Although no Salmonella were found in the pelleted samples, the presence of other Enterobacteriaceae suggests that commercial pelleting may not totally destroy Salmonella since their heat resistance is similar to the other organisms found.

Animal Feed↗
PubMed1982

Effect of various media and incubation conditions on recovery of inoculated Salmonella from poultry feed.

Samples of commercially pelleted poultry feed (30 g) were inoculated with nalidixic acid-resistant marker strains of Salmonella heidelberg or S. montevideo at levels of 1 (low), 20 (medium), or 40 (high) cells/g of feed, then 100 ml of either a nonselective preenrichment medium (lactose broth) or a selective enrichment medium [selenite cystine (SC) or tetrathionate brilliant green (TT) broth] was added and incubated at either 37 or 43 C for 24 or 48 hr in different experiments. Four selective plating media [MacConkey with 100 ppm nalidixic acid, brilliant green (BG) sulfa, modified BG, bismuth sulfite] were then streaked. MacConkey agar with nalidixic acid served as a control to which the other three plating media were compared. After 24 hr incubation at 37 C, colonies with characteristics typical of Salmonella were selected from the plates and examined biochemically and serologically to determine if they were the marker organism. In this study, preenrichment was counterproductive, because the marker organisms were recovered much more often with direct enrichment in SC or TT broth than with reenrichment in lactose broth. The TT broth produced 135 positive recoveries, whereas only 88 positive recoveries were made with SC. No differences were observed between 37 and 43 C or 24 and 48 hr incubation of the selective enrichment media. Overall efficiency of the plating media for Salmonella recovery from feed, when compared to the control (MacConkey), was BG sulfa, 65%;modified BG, 64%; and bismuth sulfite, 40%. The most effective enrichment broth-plating medium combination was TT-BG sulfa, yielding 86% positive recoveries when compared to the control.

Animal Feed↗
PubMed1981

Sampling of broiler carcasses for Salmonella with low volume water rinse.

The uneven distribution and low numbers of salmonella usually present on broiler carcasses make whole carcass rinsing the most sensitive sampling procedure for detecting this organism on the raw product. However, 270 ml of water or medium has been the smallest volume used in past published research. We found that 100 ml was adequate to recover Salmonella typhimurium, S. california, or S. montevideo from freshly processed broiler carcasses that had been inoculated with the organism at the rate of 50 cells/carcass. When carcasses were inoculated with 20 cells or S. heidelberg, then stored at -23 C for 3 or 6 months, sampling with 100 ml was adequate to detect the organism on all carcasses. The advantages of using the smallest volume of rinsing medium that will consistently lead to detection of salmonella present are: 1) less enrichment medium is required, 2) less incubator space is required, and 3) the concentration of cells in the selective enrichment medium at the end of incubation is greater; hence, the greater are the chances of salmonella detection when a drop is subsequently transferred to the selective plating medium.

Animals↗
PubMed1979

Phosphate and heat treatments to control Salmonella and reduce spoilage and rancidity on broiler carcasses.

Broiler chicken carcasses were inoculated with about 300 cells of a naladixic acid resistant strain of Salmonella typhimurium, then treated for 3 min with highly agitated water with or without 6% phosphate added, at 65, 70, 75, 80, 85, or 90 C. Other broiler carcasses were inoculated with about 60 cells, then similarly treated at 65 or 70 C. All carcasses were chilled after the hot water treatment in a system simulating commerical chilling. When inoculum was 300 cells, at least 5% of the carcasses remained contaminated with Salmonella, even when hot water treatment was at 90 C. When inoculum was 60 cells, Salmonella were eliminated by hot water treatment at 65 or 70 C. Carcasses showed a partially cooked appearance after hot water treatment. Total bacterial counts on carcasses treated at 70 and 90 C, with or without added phosphate, and then chilled were lower than on control carcasses throughout storage at 2 C for up to 26 days. Phosphates did not consistently or significantly affect either Salmonella survival or total bacterial counts. Oxidative deterioration as measured by the thiobarbituric acid test was significantly retarded throughout 26 days of storage by the addition of 6% phosphate to a 70 or 90 C hot water treatment.

Animals↗
PubMed1977

Isolation of Aleutian disease virus of mink in cell culture.

Aleutian disease virus, the causative agent of a persistent infection in mink, was isolated in a continuous line of feline renal cells when the cultures were maintained at reduced temperature (31.8 degrees). After serial in vitro passage of the virus at this temperature it had an optimum replication temperature of 37 degrees. An immunofluorescence focus assay was found to be suitable for virus quantitation. The cultured virus reproduced Aleutian disease in mink, and the virus could be reisolated from the mink 10--180 days after inoculation. The properties of the virus suggest that it is a member of the parvovirus group.

Aleutian Mink Disease Virus↗
PubMed1976

A simplified biochemical system to screen Salmonella isolates from poultry for serotyping.

The 24 most frequently isolated paratyphoids from poultry, along with Salmonella gallinarum and Salmonella pullorum, plus strains of Arizona, Citrobacter, Edwardsiella, Escherichia, Klebsiella, Prteus, Pseudomonas, Serratia and Shigella were inoculated into triple sugar iron (TSI) and lysine iron (LI) slants and into six fermentation broths which were numbered: 1 (dextrose), 2 (lactose), 3 (sucrose), 4 (mannitol), 5 (maltose), 6 (dulcitol). All the salmonella cultures (except S. pullorum) gave a 1, 4, 5, 6 code which means they produced acid, and in most cases gas, in dextrose, mannitol, maltose and dulcitol, but no acid or gas in lactose and sucrose. S. pullorum gave a 1, 4 code. All non-salmonella cultures gave a fermentation pattern different from the 1, 4, 5, 6 pattern of paratyphoids and S. gallinarum. Therefore, this six sugar system can be successfully used in the selection of suspect salmonella cultures for specific typing. Results from a miniaturized system (Minitek) were the same as those from the standard tube method for the carbohydrate fermentation tests for all cultures tested.

Animals↗