首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Abstract Unidirectional fluxes of Na+, Cl and 3-O-methyl-D-glucose (3-MG) were measured in vitro across Campylobacter jejuni live culture-infected and control rat ileal short-circuited tissues by the Using Chamber technique. Net secretion of Na+ and enhanced secretion of Cl ions was observed in the infected animals ( P < 0.001, n =6) as compared to the net absorption of Na+ and marginal secretion of Cl ions in the control animals. There was a significant decrease in the mucosal-to-serosal fluxes of 3-MG in C. jejuni -infected rat ileum. The specific Na+,K+-ATPase activity when measured biochemically in the membrane-rich fraction of enterocytes was found to be significantly lower (58%) in the infected group as compared to the control group ( P < 0.001). Our results therefore suggest that infection with an enterotoxigenic C. jejuni inhibits the Na+,K+-ATPase activity in rat enterocytes. The impairment of Na+,K+-ATPase activity thus appears to induce a secondary change in Na+,Cl and 3-MG transport in vitro in rat ileum.  相似文献   

2.
A novel method for the provision of an anaerobic atmosphere suitable for the growth of clinically significant anaerobic bacteria was evaluated. The Anaero Gen TM (Oxoid) was compared to an existing commercially available system based on the catalysis of internally generated hydrogen. The new system successfully facilitated the growth of a range of 50 strains of anaerobes and its overall performance compared very favourably with the established method.  相似文献   

3.
M. UYTTENDAELE, R. SCHUKKINK, B. VAN GEMEN AND J. DEBEVERE. 1994. NASBAR, an isothermal amplification technique for nucleic acids, was evaluated for the specific identification of Campylobacter jejuni, Camp. coli and Camp. lari. A set of primers and a probe were chosen from the 16S rRNA sequence of Campylobacter. The probe was hybridized in solution with the amplified nucleic acids of 12 Campylobacter species and nine other Gram-negative bacteria. The probe was shown to hybridize specifically to the amplified single-stranded RNA of Camp. jejuni, Camp. coli and Camp. lari in an enzyme-linked gel assay (ELGA). In a Camp. jejuni model system the combination of NASBAR and ELGA was able to detect ca 1000 rRNA molecules. The presence of an excess of Gram-negative bacteria did not influence the sensitivity of detection. A number of 6 cfu of Camp. jejuni , present in a total count of 4 times 106 cfu of Gram-negative bacteria, resulted in a positive hybridization signal.  相似文献   

4.
The survival of pathogenic bacteria was investigated during the operation of a full-scale anaerobic digester which was fed daily and operated at 28°C. The digester had a mean hydraulic retention time of 24 d. The viable numbers of Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes and Campylobacter jejuni were reduced during mesophilic anaerobic digestion. Echerichia coli had the smallest mean viable numbers at each stage of the digestion process. Its mean T90 value was 76.9 d. Yersinia enterocolitica was the least resistant to the anaerobic digester environment; its mean T90 value was 18.2 d. Campylobacter jejuni was the most resistant bacterium; its mean T90 value was 438.6 d. Regression analysis showed that there were no direct relationships between the slurry input and performance of the digester and the decline of pathogen numbers during the 140 d experimental period.  相似文献   

5.
Yoghurt: an unlikely source of Campylobacter jejuni/coli   总被引:1,自引:1,他引:0  
Knowledge of the relative insensitivity of Campylobacter jejuni to moderately acid environments prompted us to study its survival in different batches of yoghurt of pH range 4.2–5.3 and the role of organic or inorganic acid in the die-off of this pathogen. None of the 11 strains of C. jejuni or C. coli survived more than 25 min in yoghurt. Suspecting that this rapid die-off cannot be accounted for by the pH of the yoghurt we compared the survival rates of C. jejuni in milk, whose pH had been adjusted by lactic, propionic and hydrochloric acid respectively, with that of yoghurt. Even for an inoculum of 105–108 cfu/ml propionic acid was bactericidal in minutes. Lactic acid reduced the bacterial populations by 3–5 logs in 30 min. Strong inorganic acid HC1, by contrast, had little or no effect on the populations. Although lactic acid is quite bactericidal for C. jejuni , it is apparently not the only factor to which the prompt elimination of this pathogen from yoghurt could be attributed.  相似文献   

6.
The newly developed CAT campylobacter selective medium employing the blood-free charcoal-based agar containing cefoperazone (8 mg I−1), amphotericin (10 mg I−1) and teicoplanin (4 mg I−1) was compared with the membrane filtration culture technique for isolation of Campylobacter spp. including Camp. upsaliensis. Nine hundred and fifty human, 275 dog and 65 cat faeces (in which modified CCDA medium was also compared) were tested. In addition, the recovery of Camp. upsaliensis from pure cultures and from spiked human faeces was examined after membrane filtration. A 50-fold reduction in recovery after filtration using the 0·65 μm filters and a 150-fold reduction using the 0·45 μm filters was found. Recovery of Camp. upsaliensis from spiked faeces was considerably improved using the CAT medium compared with filtration, especially with the lower concentration of organisms (approx. 104 cfu ml−1). Campylobacter upsaliensis was recovered from 91 specimens of animal faeces, with CCDA recovering 26 isolates (29%), CAT recovering 76 isolates (84%) and membrane filtration (0·65 μm) recovering 82 isolates (90%). CAT selective agar was found to be a suitable medium for the isolation of thermophilic campylobacters including Camp. upsaliensis from faecal samples.  相似文献   

7.
Detection limits for Campylobacter jejuni strains JH93 and ATCC 29428 in a new blood-free enrichment broth (BFEB) were investigated under aerobic conditions. Cultures of Camp. jejuni were inoculated into 50 ml BFEB containing 10% food homogenate in 50 ml screw-cap tubes. After 24 h enrichment under aerobic conditions, Camp. jejuni were isolated on four selective agar media. The least squares means of the detection limit 50% endpoint (DL50) values were 0·4 (plain BFEB), 0·9 (crabmeat), 1·7 (mushroom), 1·7 (raw milk) and 2·1 (oyster) colony forming units (cfu) 5 g−1 food. The efficiency of the BFEB was significantly affected ( P < 0·05) by food type and bacterial strain. Overall, the BFEB enrichment compared favourably with the existing US Food and Drug Administration method under modified atmosphere. In addition, the BFEB method did not require the use of blood, special equipment or Oxyrase® to reduce oxygen tensions.  相似文献   

8.
A PCR assay has been developed for the detection of Campylobacter jejuni and Camp. coli in water samples. The sample is filtered through a membrane which is subjected to sonication to release the impacted cells. After removal of the filter from the cell suspension and a freeze/thaw cell lysis step, a semi-nested PCR is carried out on the filtrate using the primers CF02, CF03 and CF04 ( Camp. jejuni fla and flaB gene sequences). Incorporation of a sonication stage allows removal of the filter membrane since they have been shown to inhibit the PCR. In experiments with spiked water samples (20 ml) a theoretical sensitivity of 10–20 Campylobacter cells ml-1 was achieved. Using a sample volume of 100 ml this sensitivity can be increased to approximately 2 Campylobacter cells ml-1.  相似文献   

9.
On Mueller Hinton (MH) agar, Campylobacter jejuni showed 20.0 and 30.9mm zones of inhibition surrounding discs impregnated with 2.5 and 20 μg CdCl2 respectively. The minimal inhibitory concentration (MIC) ranged from 0.64 to 3.2 μg CdCl2/ml of MH agar for four C. jejuni strains. In the presence of 23 μg FeSO4/ml of MH the MIC increased to a range of 1.5–5.4 μg 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 10000 fold in three of four strains when compared with the growth in unsupplemented MH broth. Zones of inhibition surrounding 20 μg discs of CdCl2 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.  相似文献   

10.
Pieces of fresh beef were inoculated with three strains of Campylobacter jejuni . The meat was then allocated to three treatments: (a) vacuum packaged, (b) packaged in an atmosphere of 20% CO2+ 80% N2, and (c) packaged into sterile Petri dishes in anaerobic cultivation boxes, which were filled with a gas mixture of 5% O2+ 10% CO2+ 85% N2. The packaging material in the first two treatments was PA 80/PE 100–PE 100/PA 80/PE 100. The survival of Campylobacter cells was followed at 37°C, 20°C and 4°C for 48 h, 4 days and 25 days, respectively. At 37°C the counts of two Campylobacter strains increased in each package treatment for 48 h. At 20°C and at 4°C the counts of the same two strains decreased by 1 to 2 log units and 0.5 to 1 log unit, respectively, during storage. The survival of the two strains was about the same in all package treatments. The third strain was the most sensitive of the strains studied. At 37°C its numbers increased only in the optimal gas atmosphere; at 20°C the strain was not detectable after 24 to 48 h storage and at 4°C after 4 days storage. The aerobic plate counts were determined for all samples at the same time as Campylobacter counts. The high indigenous bacterial numbers of the meat samples did not appear to have a great effect on the survival or growth of campylobacters.  相似文献   

11.
To determine the optimal conditions for isolation of Campylobacter jejuni from human fecal specimens, we compared incubation atmospheres that contained about 5, 10, and 15% oxygen with the 17% oxygen produced in candle jars and also compared incubation temperatures of 37 and 42 degrees C. At 42 degrees C, C. jejuni was isolated from all 16 specimens; however, colony sizes were larger when plates were incubated in 5 and 10% oxygen than in the other two atmospheres. At 37 degrees C some positive cultures were missed in 15% oxygen and in the candle jar. The largest colony sizes were obtained in 5% oxygen. For each atmospheric condition tested, the colonies were larger at 42 than at 37 degrees C. When incubation is done at 42 degrees C, use of a candle jar is adequate; however, at 37 degrees C candle jars should not be used for isolation of C. jejuni from human feces.  相似文献   

12.
Latex agglutination for the detection of Campylobacter species in water   总被引:3,自引:2,他引:1  
A commercially available sensitized latex suspension could detect viable (102organisms/ml) or heat-killed Campylobacter jejuni. Cross-reactions with other Campylobacter spp. and Helicobacter pylori were only seen with suspensions > 105organisms/ml. In laboratory microcosms, C. jejuni remained viable for 16 d at 4°C but latex detected antigen for at least 6 months. In water from a sewagecontaminated lake, the latex gave results comparable with culture for C. jejuni but much more rapidly. Culture-negative water supplies in chicken sheds containing campylobacter-colonized birds were shown to be sometimes latex-positive.  相似文献   

13.
Outer membrane porin protein of Campylobacter jejuni   总被引:1,自引:0,他引:1  
Abstract Protein e, a 43-kDa protein from the outer membrane of Campylobacter jejuni UA580, was purified and reconstituted into lipid bilayer membranes. It was shown to form small channels with a single channel conductance of 8.82 nS in 1M KCl. Zero current potential measurements demonstrated that the channel was approx. 10-fold selective for K+ over Cl ions. A porin with a similar single channel conductance was observed in fractions from the outer membrane of Campylobacter fetus UA60.  相似文献   

14.
Abstract The relationships of nitrate-negative campylobacters (NNC) resembling Campylobacter jejuni were investigated by DNA base composition estimation (T m method) and DNA-DNA hybridization (S1 endonuclease assay). The 8 NNC strains which were from clinical material formed a homogeneous DNA group with a high level of relatedness (approx. 70%) to typical (nitrate-positive) C. jejuni , but were less similar (approx. 35%) to Campylobacter coli , and only slightly related (≥ 10%) to Campylobacter fetus, Campylobacter laridis and Campylobacter sputorum . The NNC strains showed small but consistent genome differences from typical C. jejuni . As these differences can be correlated with several bacteriological test differences, we conclude that the NNC strains constitute a distinct subspecies within C. jejuni .  相似文献   

15.
A bienzyme (tyrosinase and horseradish peroxidase) electrochemical biosensor was developed for detection of Salmonella typhimurium, and evaluated for application in a flow injection system coupled with immunomagnetic separation for food samples. Parameters for immunomagnetic separation, enzymatic reaction, flow injection and electrochemical detection were determined using pure culture samples. The selectivity was tested in the presence of Listeria monocytogenes, Campylobacter jejuni and E. coli 0157:H7. The results showed a linear relationship for logarithmic values between peak current ratio and the cell number of S. typhimurium in the range of 103 105 cfu/mL, with R2= 0.99. The detection limit of this method was 1.09 × 103 cfu/mL for S. typhimurium and the detection time was 2.5 h. Samples of chicken carcass wash water and ground beef were used to evaluate the biosensor. The results demonstrated that this biosensor has a potential for rapid detection of different pathogens in various food samples.  相似文献   

16.
Abstract A system utilizing the polymerase chain reaction (PCR), the BAX TM , was compared and validated against standard selective/enrichment assays to detect the presence of Salmonella spp. in artificially contaminated samples of raw materials and cosmetic/pharmaceutical products. After a 24 h incubation in lactose broth or lactose broth with Tween 20, the inoculated samples were analyzed both by the BAX TM system and by standard enrichment/selective methods. Standard enrichment assays required 5–7 days to confirm the presence and identification of Salmonella typhimurium , while the BAX TM system reduced the detection time to 30 h. The BAX TM system allowed a faster quality control evaluation of those raw materials and cosmetic/pharmaceutical formulations that require Salmonella spp. screening.  相似文献   

17.
The effect of different storage procedures on the ability of Preston medium to recover campylobacters was investigated. Freshly poured media was shown to recover more campylobacters than media stored under aerobic or anaerobic conditions at room temperature or at 4 degrees C. The growth of Campylobacter laridis was greatly reduced by storage of media and although most strains of C. jejuni and C. coli were not markedly affected, the growth of one strain of C. jejuni was considerably reduced. It is recommended that freshly prepared media be used whenever possible, but if storage is necessary, then plates should be held at 4 degrees C, preferably under anaerobic conditions. These precautions may not be necessary for workers interested solely in C. jejuni or C. coli, but are essential for the optimum isolation of C. laridis.  相似文献   

18.
The effect of different storage procedures on the ability of Preston medium to recover campylobacters was investigated. Freshly poured media was shown to recover more campylobacters than media stored under aerobic or anaerobic conditions at room temperature or at 4dEC. The growth of Campylobacter laridis was greatly reduced by storage of media and although most strains of C. jejuni and C. coli were not markedly affected, the growth of one strain of C. jejuni was considerably reduced. It is recommended that freshly prepared media be used whenever possible, but if storage is necessary, then plates should be held at 4dEC, preferably under anaerobic conditions. These precautions may not be necessary for workers interested solely in C. jejuni or C. coli , but are essential for the optimum isolation of C. laridis.  相似文献   

19.
Faeces and raw milk from individual cows were examined for the presence of Campylobacter jejuni . After drawing milk, the lactoperoxidase system was inactivated by raising the pH to 7.5. The organism was isolated from 22% of 904 faecal samples and from 4.5% of 904 milk samples. From laboratory experiments it could be concluded that inactivation of the lactoperoxidase system resulted in a better isolation of C. jejuni from raw cows' milk.  相似文献   

20.
Faeces and raw milk from individual cows were examined for the presence of Campylobacter jejuni. After drawing milk, the lactoperoxidase system was inactivated by raising the pH to 7.5. The organism was isolated from 22% of 904 faecal samples and from 4.5% of 904 milk samples. From laboratory experiments it could be concluded that inactivation of the lactoperoxidase system resulted in a better isolation of C. jejuni from raw cows' milk.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号