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1.
Evidence is presented that nearly all Staphylococcus aureus infections of the bovine mammary gland are by encapsulated organisms (94% of isolates examined). This observation is based on the demonstration of diffuse growth in serum-soft agar, of cultures taken directly from mastitic milk without subculture on artificial media. Only milks containing pure cultures of S. aureus were examined. It was previously reported that only 6% had capsules. Evidence is presented that as few as 3 or 4 subcultures and/or a short storage on artificial media results in loss of encapsulation of most S. aureus of bovine origin. Antisera raised against encapsulated strains inhibit the expression of capsule formation on bacteria that are encapsulated in the presence of normal serum. 相似文献
2.
Antibodies in bovine serum and lacteal secretions to capsular antigens of Staphylococcus aureus 总被引：4，自引：0，他引：4
Pregnant cows were immunized systemically with an encapsulated strain of Staphylococcus aureus (Smith diffuse strain). Antibodies in serum and colostrum were detectable by enzyme-linked immunosorbent assay and prevented capsule production by the Smith diffuse strain in a soft agar medium. Antibody in milk, although detectable by enzyme-linked immunosorbent assay, did not affect the production of capsule in vitro. Antibodies were absorbed from milk and serum, using staphylococcal surface antigen. In a 2nd experiment, lactating cows were immunized, using Smith diffuse strain antigens in the form of a bacterin or as a surface extract; the bacterin or extract was emulsified in Freund's incomplete adjuvant. Antibody titers in the milk of cows given bacterin were significantly (P less than 0.001) greater than titers in the milk of animals immunized with surface extract. The soft agar technique was insufficiently sensitive to detect antibody in the milk of any of the cattle. 相似文献
3.
Of 470 Gram-negative facultative anaerobes isolated from cases of bovine mastitis in England and Wales, 422 were identified as Escherichia coli. The characteristics of 237 of these were investigated. Guinea-pig red cell haemagglutinins were possessed by 86% of strains and 12% were resistant to D-mannose. None of the strains tested invaded Vero cells. Haemolysin, Vero toxin and enterotoxin were produced by 5, 0.5 and 1% of strains, respectively. Twenty-two percent were resistant to one or more antibiotics and 4% to sodium arsenate. Transfer ability was possessed by 41% and lysogenic phage by 27% of strains; 62% possessed either one or the other and 12% possessed both. Colicin production was detected in 18% of strains; 5% produced Colicin V. Ninety-nine percent of strains were serum-resistant, while only 6% were able to grow well in bovine serum. A microscopically visible capsule was seen in 75% of strains. All strains possessed at least one of the potential virulence factors or markers studied. Several strains which possessed one characteristic only (mannose-sensitive haemagglutination or serum resistance), possessed one or more large molecular weight plasmids. None of the strains was particularly virulent for chickens following intramuscular inoculation. Of the strains which possessed one virulence characteristic, only those which were serum-resistant were re-isolated from expressed milk following intramammary inoculation of lactating cows. 相似文献
4.
T Mattila-Sandholm T Alivehmas L Kaartinen T Honkanen-Buzalski 《Acta veterinaria Scandinavica》1990,31(2):169-174
The growth of Staphylococcus aureus and Escherichia coli was followed in bovine whey samples which had been prepared from milk previously incubated with cultures of S. aureus or E. coli. Staphylococcal strains were divided into 2 groups according to their ability to form compact or diffuse colonies on serum soft agar, which is related to the absence or presence of capsule respectively. The growth of compact staphylococci was dependent on the bulk tank milk used whereas diffuse colony forming staphylococci grew equally well in all bulk milk, also in all inoculated milk. The growth of E. coli was markedly enhanced in whey samples prepared from milk preincubated with staphylococci. However, clear growth inhibition was seen with E. coli and S. aureus strains when grown in whey prepared from milk preincubated with E. coli. Results indicate that the growth promotion of pathogens due to compositional changes in milk are of importance during the course of infection because the growth pattern on staphylococci is dependent on these compositional changes. The growth-inhibitory effects caused by E. coli may explain difficulties in isolating this organism. 相似文献
5.
A Bréard 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1990,43(4):457-458
A synthetic serum substitute (Basal Medium Supplementation, BMS), has been utilized for growing mycoplasmas. Over agar medium, colonies become atypical. In liquid medium, microscope examination only reveals coccoidal elements, and their growth is inferior in amount to that obtained with a traditional animal serum. After the tenth subculture, the bacteria recover their full characteristics when submitted to a passage on a traditional medium. Due to its known composition, this synthetic serum substitute should be usable for advanced studies of mycoplasma organisms, in molecular biology for instance, but its use for isolating strains or antigen production is not recommended. 相似文献
6.
Detection of Staphylococcus aureus in bulk tank milk using modified Baird-Parker culture media. 
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下载免费PDF全文 G W Ollis S A Rawluk M Schoonderwoerd C Schipper 《The Canadian veterinary journal. La revue veterinaire canadienne》1995,36(10):619-623
The purpose of this project was to evaluate the use of 2 selective/differential culture media for detecting Staphylococcus aureus in bulk tank milk. One medium was Baird-Parker agar base supplemented with egg york tellurite emulsion and acriflavine. The other medium was Baird-Parker agar base supplemented with rabbit plasma/bovine fibrinogen and acriflavine. An increased inoculum of bulk tank milk (0.3 mL) was used to enhance the detection of S. aureus in samples containing low numbers of organisms. The sensitivity and specificity for detecting S. aureus in bulk tank milk were 94.8% and 100%, respectively, using Baird-Parker agar base supplemented with egg yolk tellurite emulsion and acriflavine, and 89.7% and 100%, respectively, using Baird-Parker agar base supplemented with rabbit plasma/bovine fibrinogen and acriflavine. Both media are practical for detecting S. aureus in bulk tank milk and monitoring its spread in lactating dairy herds in Alberta. 相似文献
7.
本研究旨在对进口胎牛血清中的牛病毒性腹泻病毒（BVDV）进行分离及鉴定。利用BVDV抗原和抗体检测试剂盒检测,提取胎牛血清中的病毒RNA,用5'-UTR巢式PCR进行扩增,PCR扩增产物连接pMD19-T进行测序分析。胎牛血清样品接种MDBK细胞,进行细胞传代培养,通过细胞分离培养、直接免疫荧光抗体检测对实验室进口胎牛血清样品进行病毒分离及鉴定,应用DNAStar对BVDV 5'-UTR、Npro与GenBank中公布的瘟病毒参考株进行多序列比对,采用Mega 6.0进行遗传进化分析。同时通过包被脱脂奶粉进行间接ELISA检测其中的BVDV抗体。结果显示,胎牛血清中BVDV抗原和抗体均为阳性,并且从胎牛血清中成功分离到一株新的牛源BVDV,命名为BVDV-GC株,该病毒株在MDBK细胞上进行增殖培养时未能引起细胞病变;5'-UTR与Npro PCR扩增为阳性,扩增产物大小均与预期相符;直接免疫荧光检测荧光信号为阳性;病毒滴度为10-3.6TCID50/0.1 mL;遗传进化分析表明,该分离株与USMARC-60779（BVDV-2）株有较近的亲缘关系,同属于BVDV-2型毒株;通过包被脱脂奶粉和商品化的ELISA试剂盒进行检测,结果表明脱脂奶粉中存在BVDV抗体。本研究从进口胎牛血清中分离出1株BVDV-2型非致细胞病变病毒,从脱脂奶粉中检测到BVDV抗体,表明进口胎牛血清和脱脂奶粉中都存在BVDV抗原和抗体污染,本研究为后续试验分析提供参考。 相似文献
8.
The objective of the present study was to detect brucellosis in suspected dairy cattle in Khartoum State, Sudan using the conventional serological tests and tests done on milk in comparison to a PCR-based technique. Milk and blood samples collected simultaneously from suspected brucellosis cows (n = 147) in 12 different dairy farms around Khartoum State were used in the study. Overall, 54 (36.7%) of the total milk samples were positive according to the milk ring test (MRT), while 29 (19.7%) of the serum samples were positive according to the Rose Bengal test (RBT); microscopy on modified Ziehl-Neelsen-stained slides detected 13.6% of the cases, and recovery of Brucella species on both Brucella medium and tryptic soya agar was 7.5%. Thirty-three (22.4%) samples were found positive on PCR-amplified IS711 which were then taken as positive brucellosis cases. The differences of RBT and PCR-IS711 from MRT were highly significant (P < 0.05). MRT detected more cases of bovine brucellosis compared to RBT, PCR, microscopy, and culture. MRT is recommended as a noninvasive test compared to RBT, and it is less expensive compared to PCR and culture. 相似文献
9.
Blum S Heller ED Krifucks O Sela S Hammer-Muntz O Leitner G 《Veterinary microbiology》2008,132(1-2):135-148
Eleven Escherichia coli isolates from clinical bovine mastitis cases (mastitic strains) and 11 from the cowshed environment (environmental strains) were compared, to determine if the former were a subset of the latter. The mastitic and environmental strains could not be distinguished according to O antigen and antibiotic sensitivity. All mastitic isolates showed significantly (P<0.0001) faster growth in milk and faster lactose fermentation than most (approximately 64%) environmental strains, but growth rates in nutrient broth did not differ. The rates of lactose fermentation and growth in milk were positively correlated. Adhesion and phagocytosis of mastitic strains by bovine PMN were significantly (P<0.0001) lower than those of environmental strains, and correlated negatively with growth in milk and lactose fermentation. The average percentages of killing by bovine leukocytes in the two sources were not statistically different. All mastitic strains were serum sensitive, whereas most ( approximately 72%) environmental ones were resistant. Finally, pulse-field gel electrophoresis revealed two main pulse type clusters, sharing a similarity coefficient of 79%. Cluster 1 comprised only environmental strains, whereas cluster 2 comprised mostly mastitic strains and only three environmental ones. Four mastitic strains shared a similarity coefficient of less than 74% with the other strains and were not included in the clusters. Our results suggest that clinical bovine mastitis E. coli isolates may form a subset of the general environmental E. coli population; they seem better able to multiply in the udder medium and to evade the host cellular innate immune response, and are genetically distinct from most environmental strains. 相似文献
10.
Following growth in a chemically defined medium (CDM), five strains of Streptococcus uberis were tested for their ability to survive killing by bovine neutrophils. Strains 0140J, ST10, EF20 and C221 were easily killed, whereas strain C197C was highly resistant. The ability of strain 0140J to resist phagocytosis and killing was increased by supplementation of the growth medium with milk whey, casaminoacids, casein, or, to a lesser extent, bovine serum. Supplementation of the growth medium with yeast extract or bovine serum albumin did not affect the resistance of this strain. Following growth in CDM supplemented with casein, strains ST10 and C221, like strain 0140J, were significantly more resistant to killing by neutrophils. The resistance of strains EF20 and C197C was unaffected by the addition of casein to the medium; strain EF20 remained susceptible and strain C197C highly resistant to killing. The effect of supplementing the growth media with components other than casein was only studied for strain 0140J. Decapsulation of strains C197C, ST10 and 0140J, grown in CDM + casein, with type-X hyaluronidase did not significantly affect their ability to survive in the presence of bovine neutrophils. 相似文献
11.
Interaction of sub-epithelial connective tissue components with Staphylococcus aureus and coagulase-negative staphylococci from bovine mastitis 总被引：4，自引：0，他引：4
Staphylococcus aureus and coagulase-negative staphylococci (CNS) isolated from bovine mastitis were examined for their ability to interact with 125I-labelled fibronectin, fibrinogen and type II collagen. Their relative surface hydrophobicity and production of extracellular capsule were also investigated. Almost all S. aureus strains bound fibronectin (mean value 23%), fibrinogen (mean value 12%) and type II collagen (mean value 16%). CNS bound fibronectin (mean value 6%) and type II collagen (mean value 7%), but not fibrinogen (mean value 2%). The specificity of binding of these proteins to S. aureus strain F1440 and to coagulase-negative Staphylococcus chromogenes strain BO52 was studied by adding an excess of unlabelled proteins. Fibronectin and collagen binding were observed to be specific, varying between 50 and 75%, whereas the specificity of fibrinogen binding to S. aureus strain F1440 was lower (26%). Most of the S. aureus strains (63%) showed very high surface hydrophobicity (autoaggregation) or lower hydrophobicity (29% of the strains) and the rest were hydrophilic. None of the CNS strains autoaggregated, 44% were classified as hydrophilic strains. Hydrophilic strains (except the reference strains) did not show extracellular capsule production. However, the encapsulated (reference) strains showed low binding to these proteins as compared to their unencapsulated variants. Pre-treatment of S. aureus strain F1440 and S. chromogenes strain BO52 with trypsin decreased their fibronectin binding capacity and surface hydrophobicity, whereas pre-treatment with bovine milk (except on collagen binding to strain F1440) did not significantly affect binding to these proteins. These data indicate that S. aureus and CNS isolated from bovine udder infection have the ability to bind to tissue matrix and plasma proteins which may be exposed in the traumatized or toxin-damaged udder epithelial lesions. 相似文献
12.
A blocking enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against bovine leukemia virus (BLV) is described. The test is based on the biotin-streptavidin system using unlabelled polyclonal bovine IgG against BLV as catching antibody and biotinylated bovine anti-BLV IgG as detecting antibody. The sensitivity was found to be 50-100 times higher than the agar gel immunodiffusion test, with a specificity of practically 100%. The blocking ELISA proved to be suitable for detection of antibodies against BLV in serum and milk. In 34 paired milk/serum samples, the average ratio of BLV antibody titres was 1:26. So far, more than 700,000 sera have been screened by blocking ELISA for BLV antibodies in the course of the Danish surveillance programme for BLV infection. 相似文献
13.
[目的]为了解导致原料乳变质的微生物种类及其产蛋白酶活力。[方法]对广东省恒远市某规模化牧场提供的蛋白水解、脂肪上浮的变质原料乳稀释,涂布在MPC琼脂平板上。将平板于6.5 ℃恒温培养箱培养10 d,挑取形态不同的单菌落在LB液体培养基复壮增菌,提取其DNA,利用16S rDNA方法对分离的菌株进行鉴定,并对该菌株的蛋白酶活力及高温钝化后酶残留率进行测定。[结果]MPC琼脂板菌落形态单一,原料乳中分离鉴定出的两株菌均为霍氏假单胞菌,该菌株在28 ℃下对乳平板的水解圈为（15.35±0.56）mm,经135 ℃处理5 s,其蛋白酶残留率为43.63%。[结论]变质原料乳中分离到两株霍氏假单胞菌,并且该菌可产生热不敏感的蛋白酶,该酶的存在会造成原料乳中蛋白质水解,导致UHT乳在货架期内出现蛋白水解、胀包等质量问题。 相似文献
14.
Klebsiella strains isolated from the cow and its environment were biochemically and serologically characterized and evaluated for their susceptibility to normal bovine serum. Thirty-one different biotypes of Klebsiella were identified among 288 cattle and environmental strains. Of these, 56.2% were indole-positive, a greater percentage than expected for Klebsiella. Biotypes 1/1/1 and 5/1/1, most frequently isolated and constituting about 37% of the total isolates, would be considered K pneumoniae by standard biochemical typing procedures. Of 65 cattle and environmental strains studied serologically, 11 serotypes, 14 biotypes, and 29 bioserotypes were identified, indicating the diversity of Klebsiella strains present in the herd. When strains from mastitic milk (n = 19) and the environment (n = 22) were compared, no bioserotype distinction or grouping that related to isolation source was obvious. The predominant bioserotype from both sources was 5/1/1-K35 (21.0% and 22.7% of the strains from mastitic milk and the environment, respectively). The growth inhibition by bovine serum of strains isolated from mastitic milk, the environment, and udder skin was similar. However, strains isolated from the mouth and rectum of the cow were significantly (P less than 0.05) more inhibited by serum. 相似文献
15.
V Myllys M Louhi T Ali-Vehmas 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1992,39(10):723-731
Penicillin-G susceptibility was analyzed on forty staphylococcal strains isolated from mastitic bovine quarters (29 coagulase positive and 11 coagulase negative) by the standard Kirby-Bauer agar diffusion method, the epsilon-Test, the Vetmic, turbidimetric MIC analysis in Iso-Sensitest Broth (ISB) and whey. Penicillinase production was tested. Parallel susceptibility tests were carried out in whole milk, whey and ISB using resazurin and triphenyltetrazolium as the indicators of bacterial activity. The traditional susceptibility testing methods (radial agar diffusion, MIC in broth culture) showed good agreement with each other and confirmed that the tests can be used interchangeably with the current breakpoint values (0.25 micrograms/ml and phi 26 mm). The tests carried out in whey showed good correlation with the traditional tests. However, the susceptibility testings in milk resulted in additional variation. Therefore, traditional susceptibility tests of Penicillin-G in artificial media are limited in estimation of bacterial susceptibility when they grow in whole milk. The relevance of this observation regarding mastitis therapy is discussed. 相似文献
16.
Milk and dairy products are frequently contaminated with enterotoxigenic Staphylococcus aureus, which is often involved in staphylococcal food poisoning. The distribution of genes encoding staphylococcal enterotoxins (SE) in S. aureus isolated from bovine, goat, sheep and buffalo milk and dairy products was verified by the presence of the corresponding SE production. A total of 112 strains of S. aureus were tested for SE production by immuno-enzymatic (SEA-SEE) and reversed passive latex agglutination (SEA-SED) methods, while multiplex-PCR was applied for SE genes (sea, sec, sed, seg, seh, sei, sej and sel). Of the total strains studied, 67% were detected to have some SE genes (se), but only 52% produced a detectable amount of the classic antigenic SE types. The bovine isolates frequently had enterotoxin SEA, SED and sej, while SEC and sel predominated in the goat and sheep strains. The results demonstrated (i) marked enterotoxigenic S. aureus strain variations, in accordance with strain origin and (ii) the two methods resulted in different information but concurred on the risk of foodstuff infection by S. aureus. 相似文献
17.
Phagocytosis of serum-resistant and serum-sensitive coliform bacteria (Klebsiella) by bovine neutrophils from blood and mastitic milk 总被引：1，自引：0，他引：1
Phagocytic activity of neutrophil leukocytes from bovine blood and mastitic milk was determined for 2 strains of Klebsiella, 1 resistant and the other sensitive to serum bactericidal activity. Both strains were easily phagocytized in the presence of an opsonic agent, but milk neutrophils seemed to be less efficient than blood neutrophils in this respect. Phagocytosis was maximal after incubation for 60 minutes at 37 C and decreased markedly with reduction in incubation temperature. The opsonic activity of mastitic milk was considerably higher than that of normal milk and approached that of fresh bovine serum. Precolostral calf serum was deficient in opsonic activity and anti-bovine leukocyte serum was antiphagocytic. 相似文献
18.
Enhanced virulence of Staphylococcus aureus from bovine mastitis induced by growth in milk whey 总被引：3，自引：0，他引：3
The virulence towards mice of Staphylococcus aureus strains from bovine mastitis was enhanced upon growth in milk whey compared to homologous organisms grown in tryptic soy broth (TSB). In the mouse mastitis model, S. aureus grown in milk whey caused more severe lesions than homologous strains grown in TSB. Staphylococcus aureus strain F1440 grown in milk whey induced 75% mortality and local necrotic reaction in subcutaneously inoculated mice, whereas the homologous strain grown in TSB caused only 5% mortality and slight skin reaction. Extracellular capsule on milk whey-grown, S. aureus could not be demonstrated. However, diffuse type colony morphology could be correlated with an increased virulence of S. aureus towards mice. 相似文献
19.
(1) Mannitol fermentation is a reasonably reliable method for the detection of coagulase positive staphylococci in milk. This reliability can be improved if mannitol fermentation is carried out under anaerobic conditions.
(2) Among hemolytic strains of staphylococci isolated from milk, beta hemolytic staphylococci predominate. Bovine and sheep blood agar plates give similar hemolytic patterns, but the hemolysis is more pronounced on sheep blood agar.
(3) Gelatin liquefaction cannot be relied upon for the selection of coagulase positive staphylococci in milk.
(4) Urease production is a feature of the majority of coagulase positive staphylococci isolated from milk.
(5) Tellurite Glycine agar medium is not satisfactory for the selection of coagulase positive staphylococci in milk.
相似文献20.
The minimum inhibitory concentration (MIC) of ten antimicrobial drugs for 287 S. aureus strains recently isolated from bovine mastitic milk in different herds all over Sweden was determined. The minimum bactericidal concentration (MBC) of benzylpenicillin for 20 strains was determined. Thirty strains (10%) produced beta-lactamase. All strains were susceptible to oxacillin and neomycin, and more than 90% to streptomycin, trimethoprim-sulphamethoxazole chloramphenicol, erythromycin and tetracycline, whereas all were resistant to sulphamethoxazole. None of 20 strains investigated was tolerant to benzylpenicillin. However, S. aureus strains, isolated from bovine milk, should be tested for beta-lactamase production prior to treating mastitic cases with beta-lactam drugs. 相似文献