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At least 685 records · Page 38Linked to original sources
PubMed1989

In vivo effects of a thymosin alpha 1-containing colostral whey product on neutrophils and lymphocytes from lactating cows without and with experimentally induced Staphylococcus aureus mastitis.

Two separate experiments evaluated ID-1 (a commercial bovine whey product containing 5200 pg of thymosin alpha 1/ml) as an immunotherapeutic agent in lactating cows. In the first experiment, cows without mastitis were evaluated for blood leukogram, milk production, total and differential milk cell counts, lymphocyte (Lc) blastogenesis, and neutrophil (PMN) functions (random and directed migration under agarose, chemiluminescence, ingestion of bacteria, iodination, cytochrome C reduction, antibody-independent neutrophil-mediated cytotoxicity, and antibody-dependent cell-mediated cytotoxicity) before and after ID-1 therapy. ID-1 treatment resulted in a significant treatment group by time period interaction for the relative proportion of mononuclear cells (MNC) in milk (P less than 0.009) and for PMN random migration (P less than 0.01). Based on these interactions, ID-1 treatment appeared to slightly increase the proportion of small MNC in milk and to increase random migration from pretreatment levels by 73% more than increases observed in controls. No significant effect of ID-1 treatment on milk production, total milk somatic cell counts, Lc blastogenesis, or other PMN functions was observed. In cows with experimental Staphylococcus aureus intramammary infections, ID-1 treatment resulted in a significant decline in blood leukocyte count (P less than 0.001) and blood PMN count (P less than 0.02), and maintained PMN random migration (P less than 0.01) while controls declined and abrogated a depression in the ability of Lc to respond to mitogens (P less than 0.05) that developed in controls as a result of S. aureus mastitis. Injection of ID-1 into cows had no adverse effect on their overall health or level of milk production, but did cause subtle and potentially favorable changes in several in vitro immune parameters. In spite of these subtle changes which might indicate increased resistance to mastitis, cows actually developed a more severe S. aureus intramammary infection based on a 9% increase in log 10 bacterial shedding in milk.

Animals↗
PubMed1988

Etiological agents of bovine mastitis.

A total of 137 microbial species, subspecies and serovars have been isolated from the bovine mammary gland. Nucleic acid hybridization studies have restructured the classification of many mastitis pathogens. Availability of defined species descriptions has permitted greater insight into the distribution and pathogenicity of many previously unrecognized microorganisms associated with bovine mastitis. Precise epidemiological studies are needed to better delineate the role of some microorganisms in bovine mastitis and to aid development of improved control methods.

Animals↗
PubMed1992

Summer mastitis in heifers: studies on the seasonal occurrence of Actinomyces pyogenes, Peptostreptococcus indolicus and Bacteroidaceae in clinically healthy cattle in Denmark.

With the aim of investigating the seasonal occurrence of Actinomyces pyogenes, Peptostreptococcus indolicus, Bacteroides melaninogenicus ss. levii and Fusobacterium necrophorum, and thus the potential for development of summer mastitis, clinically healthy Danish Holstein-Friesian heifers due to calve in the autumn were sampled from the teat tip, the conjunctiva and the oral cavity at 2-6 week intervals from 1979 to 1981. The overall isolation rates of F. necrophorum, P. indolicus and B. melaninogenicus ss. levii, in order of significance, were significantly higher during the pasture period whereas no differences in isolation rates of A. pyogenes between housed and pastured animals were detected. F. necrophorum was recovered almost exclusively from the oral cavity, P. indolicus and A. pyogenes occurred most frequently in samples from the teat skin, whereas isolates of B. melaninogenicus ss. levii were evenly distributed between conjunctiva and teat tip samples. A distinct seasonal pattern of the isolation rates of summer mastitis pathogens was recorded, which corresponded closely to the seasonal activity of symbovine insects, in particular the headfly Hydrotaea irritans (Fallén). However, the high proportion of clinically healthy bacterial carriers as compared with the incidence of clinical disease strongly suggests that as yet unknown contributing or triggering factors, apart from the mere presence of the relevant bacterial species, are required for the establishment and development of clinical summer mastitis.

Actinomycosis↗
PubMed1994

In vitro comparison of bovine mastitis and fecal Escherichia coli isolates.

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 cytotoxicity; 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 (P < or = 0.006), production of aerobactin (P < or = 0.026), and ability to grow in 90% mastitic whey (P < or = 0.00004). 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.

Animals↗
PubMed2006

Evaluation of a novel chemical sensor system to detect clinical mastitis in bovine milk.

Automatic detection of clinical mastitis is an essential part of high performance and robotic milking. Currently available technology (conductivity monitoring) is unable to achieve acceptable specificity or sensitivity of detection of clinical mastitis or other clinical diseases. Arrays of sensors with high cross-sensitivity have been successfully applied for recognition and quantitative analysis of other multicomponent liquids. An experiment was conducted to determine whether a multisensor system ("electronic tongue") based on an array of chemical sensors and suitable data processing could be used to discriminate between milk secretions from infected and healthy glands. Measurements were made with a multisensor system of milk samples from two different farms in two experiments. A total of 67 samples of milk from both mastitic and healthy glands were in two sets. It was demonstrated that the multisensor system could distinguish between control and clinically mastitic milk samples (p=0.05). The sensitivity and specificity of the sensor system (93 and 96% correspondingly) showed an improvement over conductivity (56 and 82% correspondingly). The multisensor system offers a novel method of improving mastitis detection.

Animals↗
PubMed2006

Innate immune response of bovine mammary gland to pathogenic bacteria responsible for mastitis.

Mastitis (mammary gland inflammation) is one of the most important bovine diseases causing economic losses to dairy producers. Mammary gland inflammation is a consequence of the activity of a number of cell and soluble factors that function together to eliminate invading microorganisms. The factors involved in this inflammatory response differ depending on the infectious agent. This review analyzes the factors involved in the immunologic mechanisms against the main pathogenic bacteria causing mastitis, and emphasizes the innate immune response of the mammary gland. Knowledge, at the molecular level, of the mammary gland immune response during infection by pathogenic bacteria is fundamental to the design of effective therapies to control and eradicate bovine mastitis.

Animals↗
PubMed2005

The pathogenesis and control of Staphylococcus aureus-induced mastitis: study models in the mouse.

The intramammary colonisation by Staphylococcus aureus provokes mastitis in the cow. Once established, the infection is difficult to eradicate with available therapies and may become chronic. The present article focuses on the use of the experimental mouse model of S. aureus-induced mastitis as a practical approach for the study of bovine mastitis. Results obtained regarding the pathogenesis of S. aureus and the development of new therapeutic approaches are discussed.

Animals↗
PubMed2006

Biofilms: a role in recurrent mastitis infections?

Mastitis remains one the most important diseases in dairy cattle despite the progress made in improving general udder health in recent years. Epidemiological studies have revealed that following treatment with antimicrobials, bacteriological cure rates vary between 0% and 80% but with no evidence of a significant loss of activity of the major classes of antibiotics licensed for the treatment of bovine mastitis. Recurrent infections are often attributable to biofilm growth of bacteria and this review provides an overview of those mechanisms related to bacterial biofilm growth in mastitis. Biofilm formation is accompanied by significant genetic and subsequent physiological changes in the microorganisms resulting, inter alia, in a loss of sensitivity to virtually all classes of antibiotics.

Animals↗
PubMed2004

Immune responses to a DNA/protein vaccination strategy against Staphylococcus aureus induced mastitis in dairy cows.

The fibronectin binding protein (FnBP) and clumping factor A (ClfA) of Staphylococcus aureus are important proteins involved in the pathogenesis of staphylococcal bovine mastitis. These antigens were the targets of a DNA and protein vaccination strategy against S. aureus induced mastitis in dairy cows. The DNA vaccine comprised the bicistronic plasmid (pCI-D(1)D(3)-IRES-ClfA) that encoded the fusion of two sequences, (D1(21-34); D3(20-33)) from the fibronectin-binding motifs of FnBP and a fragment from ClfA (aa 221-550) of S. aureus 8325-4 separated by an Internal Ribosomal Entry Site (IRES) sequence. In addition, the vaccine contained the plasmid encoding the bovine granulocyte-macrophage-colony stimulatory factor gene (pCI-bGM-CSF). Four, 7-month pregnant heifers were immunized twice with the DNA vaccine and boosted once with recombinant D(1)D(3) and ClfA proteins while four others were not immunized. The immunization induced lymphoproliferative responses and functional antibodies against D(1)D(3) and ClfA antigens. Three weeks after calving, three mammary quarters of each vaccinated and non-vaccinated cow were challenged with 900 CFU/each of S. aureus Newbould 305. The fourth quarter received saline only. Serum haptoglobin levels, cardiac rhythm and the body temperature of vaccinated cows during the 24-72 h post-challenge were lower than in non-vaccinated animals. At 21 days post-challenge, bacteria were present in 5 of the vaccinated and 11 of the control challenged quarters. The bacteria averaged 1.4 and 3.3 log(10) CFU/ml of milk from vaccinated and control cows respectively. In summary, DNA-protein vaccination against FnBP and ClfA of S. aureus caused both lymphoproliferative and humoral immune responses that provided partial protection of mammary gland from staphylococcal mastitis and better post-challenge conditions in vaccinated cows.

Adhesins, Bacterial↗
PubMed2003

Dynamics of leukocytes and cytokines during experimentally induced Streptococcus uberis mastitis.

Streptococcus uberis causes a significant proportion of clinical and subclinical intramammary infections (IMI) in lactating and non-lactating dairy cows. In spite of this, its pathogenesis is incompletely understood. A study was conducted to determine leukocyte and cytokine dynamics during experimentally induced S. uberis mastitis. Five Jersey and five Holstein cows were challenged via intramammary inoculation of S. uberis into two uninfected mammary glands. Sixteen of 20 challenged mammary glands developed clinical mastitis with peak clinical signs observed at 144 h. The number of S. uberis in milk increased (P<0.05) 48 h after challenge, in spite of an increase in milk somatic cells that began at 18 h (P<0.001) and remained elevated throughout the study. Increased tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-8 (IL-8) in milk were detected 66 h after challenge (P<0.05). Peak TNF-alpha and IL-8 concentrations occurred 120 h after challenge and preceded peak clinical signs. Experimental S. uberis IMI induced local production of TNF-alpha, IL-1beta and IL-8, which may play a role in the pathogenesis of S. uberis mastitis. Other mediators may be involved in initial leukocyte recruitment to the mammary gland, since increases in milk somatic cells occurred earlier than cytokine production.

Animals↗
PubMed2004

Characterization of two proteins of Staphylococcus aureus isolated from bovine clinical mastitis with homology to glyceraldehyde-3-phosphate dehydrogenase.

Staphylococcus aureus is the most common causative agent of bovine mastitis and vaccines developed to control this disease showed limited protection due in part to the lack of common antigens among the mastitis isolates. We isolated and identified two genes encoding proteins with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity from a S. aureus strain isolated from bovine clinical mastitis. The GapB and GapC proteins share considerable homology to the GapB and GapC products of human strains of S. aureus. These two proteins could be distinguished by their different GAPDH activities and binding to bovine transferrin properties. Both gapB and gapC genes were conserved in 11 strains tested, and the GapC protein was present on the surface of all S. aureus strains.

Animals↗
PubMed2004

Antimicrobial susceptibility of mastitis pathogens from first lactation and older cows.

Increasing antimicrobial resistance has become a serious concern worldwide and antimicrobial use in animal agriculture is currently under scrutiny. Mastitis is the most common reason for antibiotic use in dairy herds and thus, antimicrobial resistance of mastitis pathogens has received recent attention. The purpose of this study was to describe and compare antimicrobial susceptibility of mastitis pathogens isolated at calving from first lactation and older cows. A total of 202 bacteria were isolated from intramammary infections (IMIs) within 3 days after calving over a 16-month study period in the Krauss Dairy Research Herd at the Ohio Agricultural Research and Development Center (OARDC) in Wooster, OH. Of these IMIs, 78% were caused by coagulase-negative staphylococci (CNS). Forty-four percent of them were resistant to at least one antibiotic. Most resistance was observed against penicillin, 39% of the isolates from older cows and 26% from first lactation cows being resistant to penicillin (P > 0.05). Also MIC90 for penicillin was higher among isolates from older cows. On the other hand, resistance to tetracycline was more common and MIC90 higher among isolates from first lactation cows than from older cows. Differences in the proportions of resistant isolates between first lactation and older cows were not statistically significant, though. The resistance patterns of the CNS isolated during the study are concordant with antimicrobial usage in the study herd. This is in agreement with the generally accepted notion that selection pressure from the use of antibiotics is a main factor in development of antibiotic resistance.

Animals↗
PubMed2005

Production of bacteriocins by coagulase-negative staphylococci involved in bovine mastitis.

In the present study, 188 coagulase-negative Staphylococcus (CNS) strains were isolated from bovine mastitis cases from 56 different Brazilian dairy herds, located in the Southeast region of the country, and were tested for antimicrobial substance production. Twelve CNS strains (6.4%) exhibited antagonistic activity against a Corynebacterium fimi indicator strain. Most antimicrobial substances were sensitive to proteolytic enzymes suggesting that they might be bacteriocins (Bac). Amongst the CNS producers, six were identified as S. epidermidis, two as S. simulans, two as S. saprophyticus, one as S. hominis and one as S. arlettae. Plasmid profile analysis of these strains revealed the presence of at least one plasmid. The Bac(+) strains presented either no or few antibiotic resistance phenotypes. Three strains were shown to produce a bacteriocin either identical or similar to aureocin A70, a bacteriocin previously isolated from an S. aureus strain isolated from food. The remaining Bac(+) strains produce antimicrobial peptides that seem to be distinct from the best characterised staphylococcal bacteriocins described so far. Some of them were able to inhibit Listeria monocytogenes, an important food-borne pathogen, and several strains of Streptococcus agalactiae associated with bovine mastitis, suggesting a potential use of these bacteriocins either in the prevention or in the treatment of streptococcal mastitis.

Animals↗
PubMed1991

Infection of rabbit mammary glands with ovine mastitis bacterial strains.

An experimental model was developed in rabbits to study ovine mastitis. A total of 19 ovine mastitis bacterial strains (seven Staphylococcus aureus, four Staph. chromogenes, four Staph. hyicus and four Escherichia coli) were used for mammary gland infections. The histopathological results showed that the ovine mastitis types corresponded to experimental infections produced in the rabbit with the ovine strains. These results helped the grading of the bacterial species tested according to the severity of their effects on the mammary gland. The most pathogenic species was Staph. aureus, followed by E. coli, Staph. hyicus and Staph. chromogenes, in that order. There was, however, variation among strains within a given species (e.g. one out of seven Staph. aureus strains gave rise to a mild infection in sheep and rabbits). The procedure was simple and consisted of introducing bacterial suspensions through alternate teat ducts of does with the help of a cannula. It helped minimize the number of animals required in the experiments.

Animals↗
PubMed1993

The pathology of experimental Mycoplasma californicum mastitis in ewes.

Mastitis was reproduced experimentally by inoculating the lactating mammary glands of 12 ewes with Mycoplasma californicum. Large numbers of mycoplasmas were recovered from the milk. The mastitis had a lobular distribution and was characterized in the early stages by degeneration of the secretory epithelium and intense leucocytic infiltration of alveolar and ductal lumina. Later there was widespread alveolar involution, and lymphohistiocytic infiltration and fibrosis of the interstitium. A monoclonal antibody-based immunohistochemical technique detected M. californicum antigen in alveolar and ductal lumina but not in epithelium or interstitial tissue. This report is the first description of the pathological features of M. californicum mastitis in ewes.

Animals↗
PubMed2000

Granulomatous mastitis in pregnancy.

BACKGROUND: Granulomatous mastitis, a rare, benign breast condition characterized by granulomas and abscess formation, is mistaken frequently for inflammatory breast carcinoma. Although it has been reported in reproductive-age women, it is unusual in pregnancy. CASE: A 25-year-old black gravida 4 para 2 developed a tender, indurated 20 x 15 x 15 cm multilobulated breast mass at 17 weeks' gestation. After not responding to antibiotics and incisional drainage, the biopsy-proved granulomatous mastitis improved with corticosteroid treatment. A postpartum recurrence also responded to steroid therapy. CONCLUSION: Granulomatous mastitis is diagnosed clinically and histologically. Early recognition and initiation of steroid treatment might prevent repetitive, deforming breast biopsies.

Adult↗
PubMed2002

Regulation of adhesion molecules on circulating neutrophils during coliform mastitis and their possible immunomodulation with drugs.

Fast neutrophil diapedesis has been demonstrated to be critical in coliform mastitis and is determining for the severity of infection. Leukocyte adhesion molecules play a pivotal role in neutrophil recruitment. Two families of cell surface proteins help to regulate the adherence of neutrophils to vascular endothelium: selectins and beta(2)-integrins. Both classes of leukocyte adhesion molecules are reviewed in the context of their dynamic expression around parturition and during acute coliform mastitis. Their potential modulation by commonly used drugs and the therapeutic implications during acute coliform mastitis are also discussed.

Adjuvants, Immunologic↗
PubMed2002

Sows intramammarily inoculated with Escherichia coli at parturition: I. Functional capacity of granulocytes in sows affected or non-affected by clinical mastitis.

The objective of this study was to investigate if occurrence of clinical disease was related to granulocyte traits in sows. Functional capacity of granulocytes and plasma steroid hormone concentrations were assessed before inoculation with Escherichia coli in the mammary glands in sows at parturition. Blood samples were taken for 3 days approximately 1 week before parturition, and granulocyte migration, phagocytic capacity and expression of CD 18 adhesion molecules were determined. Inoculation was done within 36 h before partus. Thereafter, daily thorough clinical examinations were performed including udder health, habitus, appetite and rectal temperature, to assess the severity of disease. Based on the clinical findings four sows were classified as affected and eight as non-affected by clinical mastitis within 48 h after parturition.No difference (p>0.10) in pre-inoculation chemotaxis, phagocytosis or CD 18 expression was found between granulocytes from the sows resisting and developing clinical mastitis, respectively. However, there was an effect by the individual sow (p=0.001) on the numbers of granulocytes and white blood cells, and on plasma concentrations of estradiol-17beta and progesterone. In conclusion, these data does not suggest that impaired chemotaxis or phagocytosis by blood granulocytes contribute to the development of clinical coliform mastitis in the periparturient sow.

Animals↗