Comparison of Two Plating Media for Detection of Salmonella from Swine Tissues

Xylose-lysine-Brilliant Green-agar and Brillian Green-sulfadiazine-agar were used to isolate salmonellae from swine tissues. There was no significant difference between the efficiency of the two media.     

Diagnostic Real-Time PCR for Detection of Salmonella in Food

A robust 5′ nuclease (TaqMan) real-time PCR was developed and validated in-house for the specific detection of Salmonella in food. The assay used specifically designed primers and a probe target within the ttrRSBCA locus, which is located near the Salmonella pathogenicity island 2 at centisome 30.5. It is required for tetrathionate respiration in Salmonella. The assay correctly identified all 110 Salmonella strains and 87 non-Salmonella strains tested. An internal amplification control, which is coamplified with the same primers as the Salmonella DNA, was also included in the assay. The detection probabilities were 70% when a Salmonella cell suspension containing 10³ CFU/ml was used as a template in the PCR (5 CFU per reaction) and 100% when a suspension of 10⁴ CFU/ml was used. A pre-PCR sample preparation protocol including a preenrichment step in buffered peptone water followed by DNA extraction-purification was applied when 110 various food samples (chicken rinses, minced meat, fish, and raw milk) were investigated for Salmonella. The diagnostic accuracy was shown to be 100% compared to the traditional culture method. The overall analysis time of the PCR method was approximately 24 h, in contrast to 4 to 5 days of analysis time for the traditional culture method. This methodology can contribute to meeting the increasing demand of quality assurance laboratories for standard diagnostic methods. Studies are planned to assess the interlaboratory performance of this diagnostic PCR method.     

A Rapid, Presumptive Procedure for the Detection of Salmonella in Foods and Food Ingredients

A rapid detection procedure was developed in which a lysine-iron-cystine-neutral red (LICNR) broth medium, originally described by Hargrove et al. in 1971, was modified and used to detect the presence of viable Salmonella organisms in a variety of foods, food ingredients, and feed materials by using a two-step enrichment technique. Tetrathionate broth was used to enrich samples with incubation at 41 C for 20 hr, followed by transfer to LICNR broth and incubation at 37 C for 24 hr for further enrichment and for the detection of Salmonella organisms by color change. One hundred ten samples representing 18 different sample types were evaluated for the presence of viable Salmonella. Ninety-four percent of the samples found to be presumptive positive by this method were confirmed as positive by a culture method. Fluorescent-antibody results also compared closely. A second study was conducted under quality-control laboratory conditions by using procedures currently employed for Salmonella detection. One hundred forty-three samples representing 19 different sample types were evaluated for the presence of viable Salmonella. No false negatives were observed with the rapid-detection method. The usefulness of the LICNR broth procedure as a screening technique to eliminate negative samples rapidly and to identify presumptive positive samples for the presence of viable Salmonella organisms was established in this laboratory.     

胸腺素的两种制备工艺对比

<正> 目前胸腺素或胸腺肽的生产工艺有中性提取和酸性提取等。不同工艺所得产品在活性上有无差别未见报道。我们在胸腺素简易制备工艺的基础上对比研究了中性提取和酸性提取所得产品的活性差异。     

PCR法快速检测肉食品污染沙门菌的实验研究

沙门菌属是引起食源性疾病的重要致病菌之一。传统的检测方法费时、费力,研究建立了检测肉食品中沙门菌的PCR检测方法。根据沙门菌侵袭基因invA设计一对引物,对肉食品中沙门菌基因组DNA进行PCR扩增,建立了沙门菌特异、敏感和快速的PCR检测方法,为食源性致病菌的检测提供参照,在食品检测领域中有良好的应用前景。     

Twelve-Hour PCR-Based Method for Detection of Salmonella spp. in Food

A PCR-based method for the detection of Salmonella spp. in food was developed. The method, set up on typical salami from the Italian region of Marche, is sensitive and specific and shows excellent correlation with the conventional method of reference when naturally contaminated foods are analyzed. Moreover, it can be easily performed within a maximum of 12 h from food sampling, thus allowing prompt detection of Salmonella spp. in the food stocks analyzed.     

Detection of Salmonella in Eggs and Egg Products With Fluorescent Antibody

Organisms of the genus Salmonella are detected in eggs and egg products within 24 hr in the presence of Pseudomonadaceae and other Enterobacteriaceae by combining selective cultural methods with fluorescent-antibody techniques. These techniques are specific for Salmonella when H antibodies are used. Absorption techniques are necessary before the O antibodies give specific reactions for Salmonella. No cross-reactions appear when H antiserum is used. Absorption and interference techniques indicate the test is specific for Salmonella.     

Isolation of Salmonellae From Food Samples: VI. Comparison of Methods for the Isolation of Salmonella From Egg Products

The recovery of salmonellae from egg products was studied, by use of three different enrichment procedures: (i) selenite broth, (ii) selenite broth containing 10% sterile feces, and (iii) the lactose pre-enrichment procedure. Brilliant Green Agar was used throughout as the recovery medium. Although the lactose pre-enrichment methodology promoted Salmonella recovery from samples containing small numbers of dormant organisms, the efficiency of this enrichment method is adversely affected by unfavorable coliform-Salmonella ratios. Under such conditions, early subculture of lactose broth into selenite broth is indicated. Selenite broth containing 10% sterile feces was more efficient than the lactose pre-enrichment methodology in promoting the growth of “dormant” salmonellae. Albumen adversely affected recovery of salmonellae from selenite broth, whereas whole egg and egg yolk enhanced Salmonella recovery from this medium. The selenite-feces medium presents a solution to the major problems encountered in the detection of salmonellae in egg products and offers an approach to a single medium in which food-borne salmonellae will manifest themselves with a minimum of laboratory manipulation.     

Evaluation of a Fluorescent Antibody-Enrichment Serology Combination Procedure for the Detection of Salmonellae in Condiments, Food Products, Food By-Products, and Animal Feeds

The reliability of the enrichment serology (ES), fluorescent antibody (FA), and a combination of the FA and ES procedures for the detection of salmonellae were compared to the Salmonella cultural procedure outlined in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM). A total of 126 subsamples from 22 different products were analyzed. By utilizing the BAM procedure as the reference standard, a total of 66 samples were positive for salmonellae. Within 44 h approximately 65% of the Salmonella-negative samples could be cleared by the FA test. At the end of 50 h 97% of the Salmonella-negative samples could be cleared by the combination FA-ES test. The FA procedure detected all 66 BAM positives but exhibited a high incidence of presumptive positives which were cultural negatives. The ES procedure detected 64 of the 66 BAM positives but exhibited a low incidence of presumptive positives which were cultural negatives. Incorporating positive FA and positive ES results in a combination FA-ES technique revealed that FA-ES positives were statistically equivalent to BAM positives.     

双重实时荧光PCR法检测食品和饲料中的鸡源性成分

根据鸡线粒体DNA细胞色素b基因序列和内参照基因PUC18质粒基因序列设计特异性引物和以不同荧光素标记的TaqMan探针。通过对反应条件的优化筛选,建立能同时扩增鸡源性成分和内参照基因成分的双重实时荧光PCR检测方法。设置内参照反应是为了监控反应体系中是否含有PCR反应的抑制物,避免出现假阴性结果。分别以鸡、鸭、鹅、火鸡、牛、羊、猪、鱼、兔、驴、鹿、狗、马、鸽子、大豆、玉米、小麦、大米、马铃薯及番茄的线粒体DNA作为模板进行特异性试验,结果表明该方法仅能特异性扩增鸡源性成分,而对其它物种未见有效扩增。通过灵敏度测试,该方法检出限达0.01%。所制定的方法特异性高,灵敏度好,可以作为食品和饲料中鸡源性成分的高效检测方法。     

Comparison of PCR, Electrochemical Enzyme-Linked Immunosorbent Assays, and the Standard Culture Method for Detecting Salmonella in Meat Products

An electrochemical enzyme-linked immunosorbent assay (ELISA) coupled with flow injection analysis (ELISA-FIA) and a PCR-based method using ST11 and ST15 primers for detecting salmonellae in meat were evaluated in comparison with the International Organization for Standardization (ISO) culture method. The methods were applied to experimentally contaminated and naturally contaminated meat samples. The results showed that both ELISA-FIA and PCR allowed detection of salmonella in a product contaminated with a low number of the microorganisms (1 to 10 salmonellae/25 g) after only 5 h of incubation of preenrichment broth, and they were just as effective as the ISO method.     

Comparison of Fluorescent-Antibody Methods and Enrichment Serology for the Detection of Salmonella

Four rapid methods for detection of Salmonella, (i) the conventional fluorescent-antibody (FA) technique, (ii) a rapid direct FA technique, (iii) microcolony FA, and (iv) enrichment serology (ES), were compared with conventional cultural procedures. A total of 347 subsamples representing 16 different food prototypes, alleged to be naturally contaminated with Salmonella, were analyzed. From these samples, 52 were found to contain Salmonella by cultural methods. Conventional FA identified all 52 culturally positive samples, ES identified 51, microcolony FA identified 48, and the rapid FA method identified 34. The number of false-positive samples for each procedure was: ES-selenite, 7; tetrathionate, 8; rapid FA, 26; microcolony FA, 33; conventional FA-selenite, 27; tetrathionate, 26. Tetrathionate enrichment was found to be superior to selenite for Salmonella recovery from most foods, but the concurrent use of both media allowed maximum recovery.     

Comparison of Fc N-Glycosylation of Pharmaceutical Products of Intravenous Immunoglobulin G

Intravenous immunoglobulin (IVIg) products from different pharmaceutical companies vary in composition, in part because of the selected blood donors and production process. N-glycosylation of the Fc-portion of IgG varies between blood donors and may influence both the side-effects and therapeutic effectiveness of IVIg. At present, the variation in Fc N-glycosylation between IVIg products has not been defined. Utilizing mass spectrometry, we performed relative quantitation of the Fc N-glycosylation of IgG, assessing a total of 154 unique lot numbers of IVIg. Seven products showed comparable Fc N-glycosylation, with only one product differing from the others in all glycosylation features (galactosylation, sialylation, fucosylation and bisecting N-acetylglucosamine). However, the mean difference did not exceed 3%. Within product variation was present to a minor degree, but largely indistinguishable from analytical variation. In conclusion, we expect that the minor variation in Fc N-glycosylation between IVIg products has a small effect, if any, on the biological activity.     

Comparison of Enrichment Procedures for Fluorescent Antibody and Cultural Detection of Salmonellae in Raw Meat and Poultry

No advantage was shown in preenriching raw meat samples for detecting salmonellae by fluorescent antibodies or culture. Trypticase soy-tryptose (Edwards and Ewing, 1972) was equal to or better than selenite-cystine as a postenrichment broth.     

Salmonella Types Isolated from the Gulf of Aarhus Compared with Types from Infected Human Beings, Animals, and Feed Products in Denmark

A 2-year examination for Salmonella was conducted in the gulf of Aarhus, which receives waste water from local industries and from about 100,000 inhabitants. An approximately rectilinear relationship is shown between the most probable number of Escherichia coli and species of Salmonella. Salmonella species can be demonstrated with the same frequency in inlets and outlets of the treatment plants. Data on the distribution of Salmonella types in the gulf of Aarhus and in Oeresound outside Copenhagen (1 million inhabitants) in 1966 and 1968 and the distribution in man, animals, and feeding stuff during the period 1960 to 1968 in Denmark as a whole are shown. This indicates that the classical chain of infection (feed stuff-animals-food-man) is without importance in Denmark, and that a great nlumber of the human cases may be due to increasing communication, because severa of the demonstrated types have been found neither in feed stuff nor in animals in this period. We suggest that E. coli counts, currently used in examination of waters receiving effluents of streams and sewage treatment plants, should be supplemented at intervals with qualitative Salmonella examinations.     

大豆深加工产品两种荧光定量PCR检测方法的比较研究

以内源基因Lectin作为内参照,根据RR大豆中外源基因CP4-EPSPS和内源基因Lectin设计TaqMan和SYBR GreenⅠ引物和荧光探针,使用定量PCR仪对大豆深加工产品中RR大豆的含量使用两种FQ-PCR方法进行定量检测,建立了RR大豆标准品CP4-EPSPS和Lectin之间的△Ct与样品中RR大豆含量百分比之间的校正曲线和线性回归方程,并对5种未知大豆深加工样品进行检测,同时比较二者的检测结果。结果表明,说明TaqMan和SYBR GreenⅠ两种FQ-PCR检测技术的检测结果可靠,且均可用于转基因深加工产品的检测。     

Comparison of Two Commercially Available Media for Detection of Bacteremia

An analysis of 3,795 positive blood cultures obtained from 1,718 patients in a 2.5-year evaluation of Tryptic Soy Broth (TSB) and Thiol Broth is reported. Isolation rates of Actinobacillus and Pseudomonas were significantly greater in TSB, whereas isolation rates of Streptococcus and Corynebacterium (aerobic and anaerobic) were significantly greater in Thiol. Otherwise, the two media were similar. Disregarding contaminants, anaerobic bacteria represented 11% of positive cultures and 20% of patients with bacteremia. Eleven per cent of the patients had polymicrobial bacteremia.     

鼠伤寒沙门氏菌多重PCR检测方法的研究

分别根据沙门氏菌16S rRNA、质粒毒力基因spvC、致病基因invB、fimA序列设计4对引物,对沙门氏菌株及非沙门氏株菌基因组DNA进行多重PCR检测。结果该方法能检测出6.3×10² 个cfu/ml纯培养的沙门氏菌,人工染菌食品模拟检测结果显示,熟鸡肉初始含菌量为17cfu/g、全脂奶粉为11cfu/g、生牛肉为13.6cfu/g,经过8h增菌,PCR检测为阳性。该体系能鉴定产生多种毒力因子的沙门氏菌,特异性强、敏感性高,为检测和鉴定沙门氏菌株提供了一个新方法。