Pathogenicity of Aeromonas sp. for BALB/c mice.
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Aeromonas↗
Biomedical subjects
N J Stern
Publications and source records attributed to N J Stern.
Potential pathogenic mechanisms of animal-passed virulence-enhanced strains of Campylobacter jejuni/coli.
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Animals↗
Skin-reactive properties of different cellular fractions of animal-passed C. jejuni/coli.
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Animals↗
Cadmium chloride susceptibility, a characteristic of Campylobacter spp.
We report a simple diagnostic characteristic useful in the presumptive identification of Campylobacter jejuni and Campylobacter coli. Filter paper disks impregnated with cadmium chloride were placed on streaked agar medium. Zones of growth inhibition for Campylobacter spp. occurred at 1.25 micrograms per disk. Other enteropathogens (Salmonella spp., Shigella spp., Vibrio cholerae, Vibrio parahaemolyticus, Escherichia coli, and Yersinia enterocolitica) were resistant to at least 40 micrograms per disk, with the exception of a strain of Shigella flexneri, which showed first susceptibility at 10 micrograms per disk. Most of the 52 Campylobacter strains, which were isolated from human clinical and animal sources, showed zones of inhibition greater than 10 mm with 2.5 micrograms of cadmium chloride per disk. At 20 micrograms per disk, Campylobacter isolates from clinical sources were significantly (P less than 0.01) more susceptible to cadmium chloride inhibition than were those from meat samples.
Cadmium↗
Selected enrichment broths for recovery of Campylobacter jejuni from foods.
We attempted to shorten the required time for enrichment broth culture for the isolation of Campylobacter jejuni. Enrichment broths described by Doyle and Roman and Park and Stankiewicz and one developed during this study were compared for ability to isolate C. jejuni from raw chicken carcasses. Our medium was a modification of that of Doyle and Roman with the addition of filter-sterilized FBP (0.2% ferrous sulfate, 0.025% sodium metabisulfite, 0.05% sodium pyruvate), 0.1% sodium lauryl sulfate, and 0.075% agar. Initially, laboratory strains were employed in the development of this medium. Subsequently, an indigenous load of C. jejuni obtained from chickens was used to compare media. Isolation rate comparisons were as follows: direct plating, 40%; Doyle and Roman broth, 45% at 7 h and 61% at 16 h; Park and Stankiewicz broth, 53% at 7 h and 60% at 16 h; our broth, 48% at 7 h and 50% at 16 h. In addition to having the highest isolation rate, the enrichment broth of Doyle and Roman showed greatest selectivity. Our inoculation method of indigenous bacteria provided a controlled means for comparison of isolation procedures.
Animals↗
The importance of Campylobacter jejuni to the meat industry: a review.
Campylobacter jejuni is a microorganism that only recently has been implicated in gastroenteritis in humans. As appropriate methods used for detection of the bacterium have been developed, the rates of illness caused by the pathogen were found to approach or surpass those attributed to Salmonella. Substantial evidence has been gathered to document that the route for human infection is through the ingestion of adulterated food and drink. Some slaughter animals harbor this potential pathogen among the intestinal flora and, consequently, transfer of the organism to carcasses and to the resulting meat products does occur. The most frequently implicated meat is poultry, with an incidence of recovery of C. jejuni from the store-bought poultry meat reported to be at least 50%. Red meat from slaughter animals have also yielded this bacterium from carcasses, but at lower incidence levels. Foodborne disease has been associated most frequently with the ingestion of raw milk, but poultry, hamburger, and other foods have all been implicated as potential sources. However, cause and effect relating the presence of C. jejuni in meat and human gastroenteritis has not been demonstrated. Additional research is needed to determine whether C. jejuni isolated from meat causes gastroenteritis and whether all strains of the organism are virulent. Recognition of C. jejuni as a potential meatborne pathogen by the meat industry is necessary, and appropriate sanitary practices to prevent passage of the organism through meat products should be implemented.
Adult↗
Survival of Campylobacter jejuni inoculated into ground beef.
Ground beef was inoculated with mixed cultures of Campylobacter jejuni, and the samples were subjected to various cooking and cold-storage temperatures. When samples were heated in an oven at either 190 or 218 degrees C, approximately 10(7) cells of C. jejuni per g were inactivated (less than 30 cells per g) in less than 10 min after the ground beef reached an internal temperature of 70 degrees C. When the samples were held at -15 degrees C over 14 days of storage, the numbers of C. jejuni declined by 3 log10. When inoculated samples were stored with an equal amount of Cary-Blair diluent at 4 degrees C, no changes in viability were observed over 14 days of storage. Twenty-five times as much C. jejuni was recovered from inoculated ground beef when either 10% glycerol or 10% dimethyl sulfoxide was added to an equal amount of ground beef before freezing as was recovered from peptone-diluted ground beef. Twice as much inoculated C. jejuni was recovered from ground beef plus Cary-Blair diluent as was recovered from ground beef plus peptone diluent.
Animals↗
Virulence prediction of Yersinia enterocolitica by pyrolysis gas-liquid chromatography.
Pyrolysis gas-liquid chromatography (PGLC) was used to differentiate between HeLa cell-invasive and noninvasive strains of Yersinia enterocolitica and between Sereny-positive and -negative strains. A temperature-programmed gas-liquid chromatograph, equipped with a high-resolution Carbowax 20M coated capillary column, separated the volatiles from pyrolyzed whole cells preparations and cell wall fractions. The resulting pyrolysis elution patterns (pyrograms) were divided into 313 30-s time interval areas. The time interval areas were normalized in relation to the entire pyrogram area and were evaluated by stepwise linear discriminant analysis. The results of the PGLC-statistical analyses showed good correlation in prediction of the HeLa cell invasivity test. The technique of PGLC coupled with statistical analyses is objective, in contrast to traditional methods of determining pathogenicity of Y. enterocolitica.
Bacteriological Techniques↗
Differentiation of selected Enterobacteriaceae by pyrolysis-gas-liquid chromatography.
Pyrolysis-gas-liquid chromatography was used to differentiate selected species of Enterobacteriaceae. Individual cultures of Salmonella typhi, Hafnia alvei, and Proteus vulgaris, and 12 strains of Yersinia enterocolitica were grown in nutrient broth. After harvest and lyophilization, the bacterial samples were pyrolyzed at 900 degrees C, and their volatile fractions were separated on a 50-m capillary column coated with Carbowax 20M. The resulting pyrolysis elution patterns (pyrograms) of the four species were monitored on an integrating console, which was coupled with the chromatographic detector. The pyrograms were divided into 312 30-s time interval areas, and each interval area was normalized in relation to the area of the entire curve. The normalized areas were evaluated by stepwise linear discriminant analysis, and the discriminating component coordinates were used to generate a plot of the canonical variables. Distinct clustering patterns allowed discrimination among the four genera of Enterobacteriaceae studied. The tight clustering of the 12 Y. enterocolitica strains suggests the advantage of pyrolysis-gas-liquid chromatography over traditional approaches for species identification.
Bacteriological Techniques↗
Effect of drinking water chlorination on Campylobacter spp. colonization of broilers.
The main source for Campylobacter spp. transmission from the environment to broiler chickens is still unclear. One implicated reservoir for the organism has been untreated broiler drinking water. This study was conducted with broilers first using experimental conditions (isolation units) and second under commercial conditions. We compared the rate of intestinal colonization in chickens provided 2 to 5 parts per million (ppm) chlorinated drinking water in relation to the frequency of colonization in chickens given unsupplemented drinking water. No significant difference (P > 0.05) was detected in isolation frequency or level of Campylobacter spp. colonization in birds provided chlorinated drinking water and control birds provided water without supplemental chlorine. In the isolation unit experiments, 86.3% (69/80) of the control and 85.0% (68/80) of the treated birds were colonized at levels corresponding to an average of 10(5.2) and 10(5.1) log colony-forming units (cfu) Campylobacter spp./g of cecal contents, respectively. Additionally, two sets of paired 20,000 bird broiler houses, with and without chlorination (2-5 ppm chlorine), were monitored in a commercial field trial. Effectiveness of chlorination was judged by prevalence of Campylobacter spp. in fecal droppings (960 samples) taken from the flocks in treated and control houses. Birds from the control houses were 35.5% (175/493) Campylobacter spp. positive, while 45.8% (214/467) of the samples from the houses having chlorinated drinking water yielded the organism. Chlorination of flock drinking water at the levels tested in this study was not effective in decreasing colonization by Campylobacter spp. under commercial production practices presently used in the United States.
Animals↗
Isolation of Campylobacter spp. from semen samples of commercial broiler breeder roosters.
Pooled semen samples from 12 groups of mature commercial broiler breeder roosters were analyzed for the presence of Campylobacter. Each of the 12 groups was comprised of eight individuals and was sampled weekly for five consecutive weeks. Once a day, roosters were allowed to have a restricted amount of feed after the semen samples were collected by abdominal massage. This feeding schedule reduced the amount of fecal contamination in and around the vent as well as in the semen sample. For replications 1, 2, and 3, the numbers of Campylobacter-positive groups were 8, 5, and 5, respectively, out of 12. For replications 4 and 5, 6 of 8 and 6 of 11 groups were positive, respectively. Only two groups were positive for Campylobacter at all sampling times, two groups were negative each time, and eight groups produced variable results. Also, fecal droppings, external swabs of the genitalia, and semen samples were taken from individual roosters between 49 to 65 wk of age. Of the total 275 semen samples collected, 9.47% contained naturally occurring Campylobacter, whereas 9.6% of 114 fecal droppings and 7.9% of the 114 genital swabs were positive. Levels of the organism present in the fecal samples ranged from 1.0 to 4.2 log colony-forming units (CFU)/g with an average of 2.9 log CFU/g feces. For semen, the levels ranged from as low as enrichment recovery only to as high as 3.1 log CFU/ml of semen with an average of 1.2 log CFU/ml. For swabs of genitalia, the levels of Campylobacter were so low that recovery was achieved only through enrichment. These data suggest that rooster semen may serve as a vehicle for transmission of Campylobacter to the reproductive tract of the hen and subsequently to the fertile egg.
Age Factors↗
Recovery of Campylobacter from segments of the reproductive tract of broiler breeder hens.
Three groups of >60-wk-old broiler breeder hens were assessed for the presence of Campylobacter within segments of the reproductive tract. In the first group, after stunned, the hens were bled, scalded, and defeathered, the reproductive tracts were aseptically excised from 18 hens, six from each of three adjacent floor pens that were feces positivefor Campylobacter. The reproductive tract segments (infundibulum, magnum-isthmus, shell gland, vagina, and cloaca) were pooled by pen. In the second group, 10 individual hens were sampled from the pens; the reproductive tract was divided into the following segments: magnum, isthmus, shell gland, vagina, and cloaca. For the third group, hens were obtained from two commercial farms that had been determined to be feces positive for Campylobacter, and the reproductive tract was divided into five segments, as described for the second group. Segments of the reproductive tract were placed into sterile plastic bags and suspended 1:3 (w/v) in Bolton enrichment broth, and serial dilutions were plated (0.1 ml) onto Campy-Cefex agar. The agar places were incubated at 42 C for 24 hr in a microaerobic atmosphere. In group 1, the pooled reproductive tract segments for hens from pen A were Campylobacter positive for the shell gland, vagina, and cloaca; hens from pen B were positive for the cloaca only; and hens from pen C were positive for the magnum-isthmus and doaca. In the second group, 9 of 10 cloaca samples were Campylobacter positive. Commercial hens in group 3 had campylobacter-positive cloaca samples (12/12), vagina (10/12), shell gland (7/12), isthmus (2/12), and magnum (4/12). Campylobacter colonization of the reproductive tract of the hen could enable vertical transmission of Campylobacter from the hen to the chick.
Animals↗
Relationship of messenger RNA reverse transcriptase-polymerase chain reaction signal to Campylobacter spp. viability.
SUMMARY. Discriminating viable from dead cells is of importance in the development of bacterial detection methods. A positive reverse transcriptase-polymerase chain reaction (RT-PCR) amplification signal was tested as a potential predictor of chick colonization. Some researchers have suggested that the presence of messenger RNA (mRNA) may not correlate with cell viability. Chicken colonization by cells that have positive mRNA signal but that are noncultivable would provide a correlation in cell viability and persistence of mRNA. The role of a viable but noncultivable (VBNC) form of Campylobacter spp. for colonization of poultry could be verified by such an mRNA signal. The levels of four strains of Campylobacter spp., previously isolated from poultry feces, declined progressively over time, and loss of cultivability occurred after 6 to 7 wk incubation in phosphate-buffered saline (PBS) at 4 C. Cold-stored, noncultivable and heat-inactivated (60 C for 10 min) Campylobacter spp. produced inconsistent amplified products from RT-PCR assay, depending on the target transcripts and strains used, although all fresh cultures showed mRNA signals. For the most part, signals of mRNA species from VBNC and heat-killed Campylobacter spp. AH-1, AH-2, and CH-3 persisted. RT-PCR amplification of transcripts originating from the tkt and cmp genes and a 256-base pair amplicon (from a previously described putative haem-copper oxidase) provided consistent signals, whereas transcripts from the flaA gene did not. Presumed VBNC and heat-inactivated Campylobacter spp., which produced positive mRNA signal but was not cultivable by conventional culture-based methods, did not establish colonization in the intestine of chicks 7 days after challenge. These results lead us to question the correlation between mRNA durability with cell viability as well as the significance of the VBNC cells in environmental transmission of Campylobacter spp.
Animals↗
Relationship of Campylobacter isolated from poultry and from darkling beetles in New Zealand.
Campylobacter, a foodborne pathogen closely associated with poultry, is considered to be an important agent of human gastroenteritis in New Zealand. The pathways involved in the contamination of poultry flocks remain unclear; however, many vectors, such as insects, rodents, and wild birds, have been implicated. Infestation of poultry houses by insects, particularly darkling beetles (Alphitobius diaperinus), is difficult to control. Furthermore, darkling beetles are known vectors for a variety of pathogens that include Salmonella, infectious bursal disease virus, Aspergillus, Escherichia coli, and Marek's disease virus. In this investigation, the relationship between darkling beetles and Campylobacter contamination of poultry flocks was investigated. A New Zealand breeder flock and four of its progeny broiler flocks were included in the study. Samples of beetles and of intestinal excreta of the birds were cultured for the presence of Campylobacter spp. A subset of the recovered isolates was subsequently genotyped using flaA short variable region (SVR) DNA sequence analysis. A large number of Campylobacter subtypes were isolated, indicating that Campylobacter colonization of poultry is likely to arise from a number of different reservoirs. However, a set of genetically distinct isolates were found to be common to the broiler flocks and to the beetles. This research provides data that indicates that Alphitobius diaperinus may serve as a source of Campylobacter contamination of poultry. A more thorough understanding of the relationship between beetle infestation and the Campylobacter status of poultry flocks should enable progress in further development of biosecurity control measures.
Animals↗
Campylobacter jejuni--an emerging foodborne pathogen.
Campylobacter jejuni is the most commonly reported bacterial cause of foodborne infection in the United States. Adding to the human and economic costs are chronic sequelae associated with C. jejuni infection--Guillian-Barré syndrome and reactive arthritis. In addition, an increasing proportion of human infections caused by C. jejuni are resistant to antimicrobial therapy. Mishandling of raw poultry and consumption of undercooked poultry are the major risk factors for human campylobacteriosis. Efforts to prevent human illness are needed throughout each link in the food chain.
Animals↗
Cecal carriage of Clostridium perfringens in broiler chickens given Mucosal Starter Culture.
Day-of-hatch broiler chicks housed in isolation units were each given, by oral gavage, 0.1 ml of Mucosal Starter Culture (MSC) or saline control. Each of the treated and control chicks was subsequently given a composite culture of three strains of bacitracin-resistant Clostridium perfringens (Cp) previously isolated from chickens with symptoms of necrotic enteritis. Some chicks were maintained on a corn-based diet provided ad libitum. Others were given the feed supplemented with 50% rye (a predisposing factor for necrotic enteritis). At 7, 14, and 21 days after receiving Cp, chicks were euthanatized, and cecal contents were diluted and plated on selective agar containing bacitracin. For chicks on corn feed, Cp numbers were similar in control birds and birds given MSC in three of four trials. In two of the trials that demonstrated no effect of MSC on Cp numbers, enterotoxin presence was determined. The number of birds with detectable Cp enterotoxin in their small intestine and the mean toxin levels were lower in the MSC-treated birds. In a fourth trial with birds on corn-based feed, mean Cp numbers and the number of Cp-positive birds were lower in the MSC-treated birds. For the two trials involving chickens on rye-supplemented feed, Cp numbers and the percentage of Cp-positive birds were significantly reduced in MSC-treated birds compared with control birds. Enterotoxin in birds receiving the 50% rye diet was at low levels or not detected in control and MSC-treated birds. Results suggest that MSC may reduce intestinal proliferation of Cp, a causative agent of necrotic enteritis in poultry and of foodborne disease in humans.
Animal Feed↗
Determination of the incidence of Salmonella spp., Campylobacter jejuni, and Clostridium perfringens in wild birds near broiler chicken houses by sampling intestinal droppings.
Several methods were evaluated for collecting fecal and intestinal samples from wild birds found near broiler chicken houses. A few intestinal samples and cloacal swabs were obtained from European starlings and house sparrows. Most of the samples collected consisted of wild bird droppings found on or near the houses. Samples were collected from each of four farms of a broiler integrator during a grow-out cycle: a cycle in the summer for farm A, fall for farm B, and spring, summer, fall, and winter for farms C and D. Of the 25 wild bird intestinal and fecal samples collected from a broiler house on farm A during a grow-out cycle in July-August 1997, 24% were positive for Salmonella spp., 4% for Campylobacter jejuni, and 28% for Clostridium perfringens. Of the nine fecal samples collected from broiler house B in a grow-out cycle in September-November 1997, 33% were positive for Salmonella spp., 11% for C. jejuni, and 22% for C. perfringens. For farms C and D, of the 23 samples collected in March-April 1998, 0 were positive for Salmonella spp., 11% for C. jejuni, and 52% for C. perfringens; of 27 samples collected in June-July 1998, 4% were positive for Salmonella spp., 0 for C. jejuni, and 13% for C. perfringens; of 24 samples collected in August-October 1998, 14% were positive for Salmonella spp., 5% for C. jejuni, and 4% for C. perfringens; of 14 samples collected December 1998-January 1999, 0 were positive for Salmonella, 50% for C. jejuni, and 14% for C. perfringens. The incidence of these bacterial enteropathogens in wild birds near the broiler chicken houses suggests that wild birds that gain entry to poultry grow-out houses have the potential to transmit these pathogens to poultry.
Animals↗
Prevalence of Clostridium perfringens in commercial broiler hatcheries.
Clostridium perfringens, a cause of human foodborne and poultry disease, has been isolated from the intestinal tract of poultry and from the processed carcass. Little is known about the incidence and sources of this pathogen in the poultry production environment. To determine if the broiler hatchery is a possible source of C. perfringens, we collected samples from three hatcheries, each operated by a different poultry integrator, and the presence of C. perfringens in these samples was determined. For each sampling period, eggshell fragments, chick fluff from the hatcher, and paper pads stored in the hatchery before use with chicks and after placement beneath chicks for 1 hr were evaluated. Clostridium perfringens was found in eggshell fragments, fluff, and paper pads in each of the three hatcheries. The percentages of C. perfringens-positive samples from the three hatcheries ranged from 13% to 23%, with an overall incidence of 20%. Positive samples were consistently found, i.e., detected on each of the nine sampling days (three sampling days for each of three hatcheries). These results suggest that the hatchery is a potential source/reservoir for C. perfringens in the integrated poultry operation.
Animals↗