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1.
The antibacterial effect of lactoferrin (Lf) was tested on isolates of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and coagulase-negative staphylococci (CNS) as well as on Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae), originally isolated from bovine mastitis. Concentrations of Lf used were 0.67 mg/ml, 1.67 mg/ml, and 2.67 mg/ml. Growth of udder pathogens was monitored by turbidometry either in broth culture or in whey prepared from normal milk. We focused on 3 different growth variables: lag time, slope, and maximum absorbance of bacterial growth curves. Growth inhibition was seen in the broth but hardly at all in whey. The isolates of E. coli and CNS did not grow sufficiently well in whey to draw any conclusions. The most effective inhibitory activity of Lf was seen against E. coli and P. aeruginosa. All 5 E. coil isolates had similar growth patterns. Inhibition of growth by Lf was concentration-dependent. The concentration of 0.67 mg/ml in broth and whey was generally too low for a significant inhibitory effect.  相似文献   

2.
The concentrations of lactoferrin (Lf) in quarter milk from normal lactating cows and subclinical mastitic cows were measured to determine whether the Lf concentration in milk is influenced by the age of the cow, the stage of lactation, number of milk somatic cells and the presence of pathogens. Lf concentrations in 111 quarter milk samples from 28 normal lactating cows and 270 quarter milk samples from 198 subclinical mastitic cows were measured by means of a single radial immunodiffusion test. Lf concentrations (means +/- standard deviations; logarithmic form) in normal cows and subclinical mastitic cows were 2.23 +/- 0.39 and 2.70 +/- 0.39, respectively. The mean milk Lf concentration (log) in subclinical mastitic cows was significantly (p<0.01) higher than that in normal cows. The mean milk Lf concentration (log) in normal lactating cows aged 5 years was lower than those in normal lactating cows aged 2 years (p<0.01) and 3 years (p<0.05). The results showed that the milk Lf concentration (log) is associated with age of the dairy cow (one-way analysis of variance test, p<0.01). The mean milk Lf concentration (log) in the latter lactational period tended to be higher than those in the peak and middle periods. Milk Lf concentrations (log) tended to be proportional to the level of the somatic cell count (SCC) score. Mean milk Lf concentrations (log) in subclinical mastitic cows infected with Staphylococcus aureus and with other streptococci species were significantly (p<0.01) higher than those in cows infected with coagulase-negative staphylococci and with Corynebacterium bovis.  相似文献   

3.
The Fc receptors on leukocytes obtained from normal milk, colostrum, nonlactating gland secretion, and mastitic milk were detected by rosette formation, using sensitized erythrocytes. The percentage of leukocytes bearing Fc receptors from normal milk was significantly (P less than 0.01) greater than that from other secretions. Fc receptors were found primarily on polymorphonuclear leukocytes from normal milk, mastitic milk, and colostrum. However, in nonlactating gland secretion obtained 6 weeks after milking was completed, Fc receptors were predominantly on macrophages. The low percentage of leukocytes bearing Fc receptors obtained from colostrum, nonlactating gland secretion obtained 7 days after milking was completed, and mastitic milk was associated with the presence of a blocking factor in these secretions, which specifically attached to Fc receptors. These secretions significantly (P less than 0.01) blocked the Fc receptors on leukocytes from normal milk and on other cells bearing FC receptors. The presence of Fc receptors on leukocytes obtained from normal milk was related to a high percentage of phagocytizing leukocytes through Fc receptors and a large number of phagocytized bacteria (phagocytic activities). In contrast, the low percentage of leukocytes bearing Fc receptors from colostrum, from nonlactating gland secretion (7 days after milking), and from mastitic milk was associated with depressed phagocytic activities. Preincubation of leukocytes from normal milk with whey from colostrum, nonlactating gland secretion (7 days after milking), and mastitic milk significantly (P less than 0.01) inhibited phagocytosis. This effect was associated with the blocking of Fc receptors by these secretions. Possible mechanisms for and implications of these findings are discussed.  相似文献   

4.
We have identified various lactoferrin (Lf) molecules in mastitic mammary gland secretions (MGSs), and these Lf molecules were examined for their physiological function in MG. These Lf molecules were isolated by Con A affinity chromatography, and then analyzed by various electrophoresis methods and N-terminal amino acid sequencing. The low Con A affinity Lf was found to have low molecular peptides as compared with the 86 kDa of the high Con A affinity Lf, which is usually detected in healthy MGSs. The N-terminal amino acid sequence of each of the small molecular Lfs were confirmed as fragments of 86 kDa Lf. This low Con A affinity Lf stimulated spleen adherent cells to produce more O(2)(-) than 86 kDa Lf. Furthermore, the low Con A affinity Lf showed low antibacterial activity against E. coli and S. aureus, and had decreased iron-binding capacity in comparison with 86 kDa Lf. Moreover, the 86 kDa Lf could stimulate bovine T cells or macrophages to produce IFN-gamma, IL-4, IL-6, and IL-1alpha. However low Con A affinity Lf induced the production of TNFalpha, but not physiological T cell or macrophage cytokines. It was also found that when the healthy MGs of dry cows were injected with the low Con A affinity Lf, there was an increase in polymorphonuclear cells together with TNFalpha, MCP-1, and IL-8 production. These results suggested that low Con A affinity Lf in mastitic MGSs differed from 86 kDa Lf in physiological characteristics, and, that it induced an inflammatory reaction in MGs.  相似文献   

5.
Milk IgA was seen to be largely associated with milk fat globules ( of the sIgA in whole milk). Isolated fat globules became agglutinated by anti-IgA and to a lesser degree by anti-IgM but not by anti-IgG1 or anti-IgG2 (microscopic plate agglutination). Absorption studies using anti-bovine sIgA showed that the cream contained some 16 times more IgA than the repective whey. Isolated milk fat globule membranes released IgA and SC when treated by Triton X 100 as demonstrated by double gel diffusion. IgA was the only membrane-associated component showing cross-reactivity with serum proteins in immunoelectrophoresis. An antiserum prepared against fat globule membranes showed strong anti-IgA activity. IgA from whey became absorbed into washed cream. The specificity of MFGM associated immunity was demonstrated by analysing the capacity of cream, isolated from mastitic cows, to bind homologous labelled bacteria (cream-rising test).  相似文献   

6.
In vitro methods were used to test the hypothesis that Escherichia coli from bovine mastitis are essentially no different from isolates from bovine feces. Fifty E. coli isolates from bovine mastitic milk, 50 from feces of mastitic cows and 50 from feces of healthy cows were compared with respect to biochemical properties and certain potential virulence factors. There were no significant differences among the groups in tests for biotype; production of colicins, colicin V, or Vero cell cytotocity; and growth in 90% gnotobiotic calf serum or 90% normal milk whey. Resistance to killing in 90% gnotobiotic calf serum varied from 66 to 84%. Most isolates grew in normal whey: the percentage in a group varied from 86 to 96. Mastitic milk isolates were significantly different from the fecal isolates in adonitol fermentation (P0.006), production of aerobactin (P0.026), and ability to grow in 90% mastitic whey (P0.00004). However, only 40% of mastitis E. coli fermented adonitol and only 20% produced aerobactin. Ninety-six percent of mastitic milk E. coli grew in mastitic whey, whereas 64% and 60%, respectively, of mastitic fecal and normal fecal isolates grew in this medium. It is concluded that none of the properties that were investigated constitute potential virulence factors or markers for ability to induce mastitis; the data are consistent with the hypothesis that mastitic E. coli are simply opportunistic pathogens.  相似文献   

7.
OBJECTIVE: To determine the antibacterial activity of bovine lactoferrin hydrolysate (bLf-lysate) alone or in combination with other antimicrobials against antimicrobial-resistant Escherichia coli strains isolated from baby pigs. SAMPLE POPULATION: 3 clinical strains of E coli were isolated from baby pigs with severe diarrhea and designated as strains 9061, 9062, and 9065. PROCEDURE: The broth microdilution checkerboard and fractional inhibitory (or bactericidal) concentration index were used to evaluate the antibacterial effect elicited by bLf-lysate in combination with kanamycin, gentamicin, cephalothin, cefamandole, penicillin G, ampicillin, tetracycline, erythromycin, or rifampicin against the 3 strains of E coli. RESULTS: The 3 strains of E coli were susceptible to gentamicin and rifampicin but highly resistant to most of the other antimicrobials tested, except for strain 9061 that was also susceptible to cephalothin but intermediately inhibited by kanamycin and cefamandole. Synergistic growth-inhibitory activity was observed between bLf-lysate and gentamicin against 1 strain of E coli (strain 9062); synergistic bactericidal activity was found between bLf-lysate and rifampicin against all 3 strains of E coli. Moreover, partial synergy was observed between bLf-lysate and kanamycin, gentamicin, cephalothin, or cefamandole against the strains of E coli, but this partial synergistic activity was mostly seen against only 1 of the strains. Little interaction between bLf-lysate and tetracycline, ampicillin, penicillin G, or erythromycin was observed against the clinical strains of E coli. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of bLf-lysate and certain antimicrobials may prove clinically effective against antimicrobial-resistant strains of E coli.  相似文献   

8.
Milk samples were collected from 21 non-pregnant cows to study the ability of milk whey to support in vitro bactericidal activity of neutrophils against Actinomyces pyogenes. Significant differences (P less than 0.01) existed in opsonising ability of milk whey samples from individual cows. Antibody titres to A pyogenes in milk whey were determined using an enzyme linked immunosorbent assay. Bactericidal activity of neutrophils incubated with milk whey was positively correlated (P less than 0.05) with titres of IgG2 and IgM antibodies but not with IgG1 or IgA antibodies.  相似文献   

9.
为了研究药用植物内生真菌的次生代谢产物是否具有抑菌活性,以96株罗汉松内生真菌为研究材料,将菌丝及其培养液经氯仿-甲醇抽提后,采用杯碟法测定了全部菌株的抑菌活性。罗汉松内生真菌中49%的菌株具有抑菌作用,其中菌株LHS18、LHS42、LHS67、LHS92和LHS93抽提物经100倍稀释后对金黄色葡萄球菌仍有强的抑菌作用,菌株LHS30抽提物的100倍稀释溶液对大肠杆菌的生长有强烈的抑制作用。对抑菌活性较强的6株菌根据其ITS序列相似性进行了分子鉴定。菌株LHS18和LHS42鉴定为烟曲霉（Aspergillus fumigatus）,LHS92为四孢脉孢菌（Neurospora tetrasperma）,LHS30为丝枝霉（Aphanocladium sp.）,LHS67为拟茎点霉（Phomopsis liquidambari）,LHS93未能鉴定出种属。研究结果提示,罗汉松内生真菌中49%菌株具有抑菌活性,其中6株菌对动物和人类的病原菌有强列的抑制作用,是挖掘高效抑菌物质的重要资源。  相似文献   

10.
Antibacterial activity of short hydrophobic and basic-rich peptides   总被引：2，自引：0，他引：2  
OBJECTIVE-To design short and potent analogs of bovine lactoferricin by use of the concepts of lipophilic bulk and cationic charge. SAMPLE POPULATION-5 synthetic peptides of bovine lactoferricin. PROCEDURE: Antibacterial peptides were constructed by synthesizing several decapeptides rich in arginine and tryptophan. Basic residues of bovine lactoferricin (bLf 20-29; residues 20 to 29) were modified by substitution with arginine or lysine and nonbasic residues were modified by substitution with tryptophan, phenylalanine, or isoleucine. Synthetic peptides of bovine lactoferrin (LFB) were designated as LFB-RW (RRWWWRWRRW), LFB-KW (KKWWWKWKKW), LFB-RWa (RRWWRRWRRW), LFB-RF (RRFFFRFRRF), and LFB-RI (RRIIIRWRRI), where R, K, W, F, and I stand for arginine, lysine, tryptophan, phenylalanine, and isoleucine, respectively. Peptides were evaluated by determining their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. RESULTS: LFB-RW, LFB-KW, and LFB-RWa possessed equivalent potency as bLf 20-29 against E coli. LFB-RW and LFB-RWa had a 2-fold increase in growth-inhibitory and bactericidal activity against S aureus, compared with bLf 20-29. LFB-RI had the lowest MIC value against E coli among the peptides but lost bactericidal activity. LFB-RW and LFB-KW had stronger bactericidal activities against S aureus or E faecalis, respectively, as well as E coli than the other synthetic peptides. LFB-RF also had antibacterial activity, but this was 2-fold less than that of LFB-RW, as determined by MIC and MBC values. CONCLUSIONS AND CLINICAL RELEVANCE: In construction of potent antibacterial peptides, inclusion of arginine, lysine, tryptophan, or isoleucine residues enhances effectiveness against certain bacteria, as measured by MIC or MBC values.  相似文献   

11.
考察马波沙星对猪临床分离病原菌的体外抑菌活性,以期为临床应用提供依据。采用琼脂二倍稀释法测定马波沙星对猪临床分离大肠杆菌、金黄色葡萄球菌和链球菌的最小抑菌浓度(MIC),并以土霉素、恩诺沙星、诺氟沙星、环丙沙星、庆大霉素和多西环素作为对照药物。结果表明:马波沙星对猪临床分离病原菌大肠杆菌、金黄色葡萄球菌和链球菌均有较低的最小抑菌浓度,对临床分离大肠杆菌、金黄色葡萄球菌和链球菌的抑菌活性明显高于诺氟沙星、环丙沙星、庆大霉素和强力霉素,对临床分离大肠杆菌的抑菌活性高于恩诺沙星。马波沙星对引起猪乳房炎-子宫炎-无乳综合征(MMA)的主要病原菌的抑菌活性优于常用抗菌药。  相似文献   

12.
Zhen YH  Jin LJ  Guo J  Li XY  Lu YN  Chen J  Xu YP 《Veterinary microbiology》2008,130(1-2):126-133
The objective of this study was to estimate the in vitro activity of egg yolk immunoglobulin (IgY) against mastitis-causing Escherichia coli. Specific IgY was produced by hens immunized with formaldehyde killed E. coli O111 in long-standing immunization response (titer > or =6400 for 100 days) and was isolated from yolks with a purity of 86% by water dilution, salt precipitations and ultrafiltration. Enzyme-linked immunosorbent assay (ELISA) indicated the produced IgY specifically targeted E. coli O111 and five other E. coli strains which were isolated from mastitic cows. The growth inhibition activity of the specific IgY to bacteria was dose-dependent with an effective concentration of 20mg purified IgY per milliliter. The phagocytic activity of E. coli either by milk macrophages (MPhi) or by polymorphonuclear neutrophil leukocytes (PMN) in the presence of specific IgY was significantly higher than that with nonspecific IgY or without IgY (p<0.05), suggesting that it enhanced phagocytic activity. The current work suggests that this specific IgY has potential as a therapeutic treatment for mastitis in dairy cows.  相似文献   

13.
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   

14.
Two neutrophil defensins, rabbit peptides NP-1 and NP-5, were examined for their in vitro antibacterial activity against a panel of Gram-positive and Gram-negative organisms isolated from mastitic cows. Incubation for 60 minutes with 5 micrograms/ml of NP-1 in 10 mM sodium phosphate buffer resulted in substantial killing (greater than 95%) of all organisms tested. Although NP-5 was virtually inactive under these same conditions, supplementation of the incubation mixture with dilute nutrient media sensitized otherwise resistant organisms to this defensin. For both NP-1 and NP-5, bactericidal activity was dependent on time and concentration. Our findings demonstrate that the spectrum of defensin bactericidal activities include clinically important bovine pathogens. Further, the data demonstrate that NP-1 and NP-5, peptides which are homologous in 18 of their 33 residue positions, possess distinct mechanisms of action.  相似文献   

15.
We examined the effective diagnostic indicator using the concanavalin A (Con A) low-affinity lactoferrin (Lf) to mastitic drying cows. The concentrations of both Lf and Con A low-affinity Lf in mammary gland secretions (MGSs) were lower than normal MGSs at the early and middle dry periods and colostrums. On the other hand, the levels of Con A low-affinity Lf in MGSs increased following the appearance of mastitis symptoms, and decreased when the mastitic symptoms were cured. Moreover, IgG1 concentrations of colostrums decrease on the quarters where a high level of Con A low-affinity Lf was determined after the onset of dry period. These results suggest that this method could be used as a useful indicator to mastitic drying cows.  相似文献   

16.
头孢喹诺对临床分离菌株抗菌活性研究   总被引：1，自引：0，他引：1  
本研究旨在评价头孢喹诺对上海市养殖场临床分离菌株的体外抗菌作用,为头孢喹诺的临床使用提供参考依据。从上海市养殖场分离并鉴定大肠杆菌、沙门氏菌、金黄色葡萄球菌和链球菌各若干株,采用微量肉汤稀释法测定头孢喹诺对各菌株的最小抑菌浓度（MIC）、最小杀菌浓度（MBC）,推算MIC50和MIC90,并绘制头孢喹诺对这4种细菌的杀菌动力学曲线。头孢喹诺对金黄色葡萄球菌、链球菌、沙门氏菌和大肠杆菌的MIC50分别为0.063、0.063、0.032、0.125 μg/mL,MIC90分别为0.125、0.125、0.125、0.25 μg/mL;在很小的浓度变化范围内头孢喹诺能够快速抑菌,在抑菌浓度为1倍或2倍MIC时,24 h内能杀灭金黄色葡萄球菌、大肠杆菌或链球菌、沙门氏菌。头孢喹诺对上述几种临床分离细菌具有很强的抑菌效果和杀菌活性。  相似文献   

17.
To determine the N-acetyl-B-D-glucosaminidase (NAGase) and B-glucuronidase (B-Gase) activities in mastitic milk, basic enzyme assay conditions, distribution of NAGase and B-Gase, comparison of their activities with California Mastitis Test scores, and the effects of the milking process on their enzyme activities were examined. The mean NAGase and B-Gase activities in milk macrophages were about threefold higher than those of milk and blood polymorphonuclear cells. Very little NAGase activity appeared to be associated with blood mononuclear cells, whereas a relatively higher B-Gase activity was observed. California Mastitis Test scores of each group (1 to 5) appeared to be well correlated (r = 0.86 for NAGase and 0.92 for B-Gase) with the levels of NAGase and B-Gase activity. The milking process was least effective in the normal milk, but some variations of enzyme activities during milking in mastitic milk were found. Changes in NAGase and B-Gase activities in quarter milk were well monitored during the course of clinical mastitis.  相似文献   

18.
Two methods for estimating fat and cream content in cow's milk were compared in normal and mastitic milk. Fat content in milk from periparturient cows was estimated simultaneously by the method of Gerber and by simply spinning small samples of untreated milk in a haematocrit centrifuge. Mastitis was experimentally induced by inoculating mammary glands with Escherichia coli. On the average, cream content in milk from normal, and uninfected mammary glands measured by the haematocrit method was 20 to 23% higher than milk fat measured by the method of Gerber. In mastitic milk from infected mammary glands haematocrit readings were 40% higher than those of Gerber. Milk fat values as measured by both methods were highly correlated. It is concluded that the haematocrit method can be used for rapid estimation of milk fat content in normal milk of cows. The greater difference between cream and fat content in mastitic milk compared to normal milk can probably, at least partly, be ascribed to the presence of large clots of cells and fat in the milk during mastitis. During centrifugation of the viscous mastitic milk samples, milk cells and fat probably are not completely separated. This results in overestimated readings of milk cream content with the haematocrit method. It therefore seems advisable to use the Gerber method for accurate measurements of milk fat in mastitic milk.  相似文献   

19.
Inflammatory cytokines, such as interleukin (IL)-6, have been shown to reflect clinical signs in certain conditions in diseased animals. In this study, we quantified the IL-6 concentrations in the serum and milk whey from 94 dairy cows with acute clinical mastitis and 55 healthy lactating cows. The IL-6 concentrations in serum from mastitic cows were significantly higher on the first day of illness compared to those of normal cows. Higher concentrations of IL-6 were also detected in the whey from mastitic cows, whereas low concentrations of IL-6 were detected in both serum and whey samples from normal cows. IL-6 concentrations in the serum taken at the onset of illness from cows that later required euthanasia were significantly higher than those in samples from cows that later recovered. These results suggest that serum IL-6 concentrations may be of prognostic value in identifying cows with severe mastitis.  相似文献   

20.
We examined combination therapy with both lactoferrin (Lf) and antibiotics on clinical mastitis due to Staphylococcus aureus (S.aureus) on drying cows. The clinical symptoms of mastitic quarters were cured 81% of combination therapeutic quarters at 7 days post injection (dpi). Moreover, most of mammary gland secretions (MGSs) in combination therapeutic quarters were normal at 7 days after parturition. In the quarters with combination therapy, S.aureus counts, Lf concentrations and content rate of concanavalin A (Con A) low-affinity Lf decreased and were lower than in the quarters treated with Lf or antibiotics alone. The mRNA expression of tumor necrosis factor alpha (TNFalpha) of the quarters with combination therapy also decreased and was lower than that of the Lf or antibiotics treated. The mRNA expression of pro-inflammatory cytokines and chemokines in bovine mammary gland epithelial lined cells (BMEC) stimulated with Lf were lower than those of Con A low-affinity Lf stimulated BMEC. Moreover, Lf showed an inhibitory effect to the induction of pro-inflammatory cytokine mRNA expression when co-stimulated with Lf and Con A low-affinity Lf. Nuclear factor kappa B (NFkappaB) activation was also induced with Con A low-affinity Lf, and the inhibitory effects of Lf were also confirmed on BMEC co-stimulated with Lf and Con A low-affinity Lf. These results indicated that the efficacy of combination therapy with antibiotics and Lf caused antibacterial effect of antibiotics and inhibition of pro-inflammatory cytokine and chemokine production with Lf via the inhibition of NFkappaB activation.  相似文献   

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