Species identification and some characteristics of coagulase-negative staphylococci isolated from bovine udders

The species of 203 strains of coagulase-negative staphylococci (CNS), isolated from bovine udder quarters was determined; all were tested for hydrophobicity and encapsulation, attributes that may relate to virulence. Twelve species were identified, of which Staphylococcus simulans, (34.5%), S. chromogenes (16.7%), S. epidermidis (13.8%) and S. xylosus (8.9%) were the most frequent. The majority of strains possessed a hydrophilic cell surface. However, strains from two species (S. chromogenes and S. epidermidis) were more hydrophobic than the others. Only five strains were encapsulated (S. xylosus, 3; S. saprophyticus, 1; and S. sciuri, 1). Judging from the low frequencies of hydrophobic and encapsulated strains, and comparing with strains isolated from clinical cases, it is suggested that these properties are not major virulence determinants of CNS.

Bacteriological investigations of clinical mastitis in heifers in Sweden

Bacterial analyses were carried out of 2069 udder secretions, isolated from 1481 heifers with mastitis in eight veterinary districts in Sweden. Streptococci, e.g. Streptococcus dysgalactiae and Str. uberis, dominated the bacterial flora, being isolated from 34.4 and 19.5% respectively of heifers with clinical mastitis occurring from puberty up to 14 d post partum. Bacterial species generally regarded as important pathogens in the summer mastitis complex, e.g. Actinomyces pyogenes, Stuart-Schwan coccus and strictly anaerobic bacteria such as Peptostreptococcus indolicus, Fusobacterium necrophorum and Bacteroides melaninogenicus were isolated at low frequencies (13.2, 6.3, 9.4, 3.8 and 1.3% respectively). When the cases of mastitis studied were restricted to those appearing in heifers pre partum, May 15 to October 14 (summer mastitis), these bacterial species were isolated at higher percentages (27.1, 14.4, 21.4, 13.5 and 5.2% respectively). These figures were, nevertheless, still lower than those published in reports from other countries. Whether considered up to 14 d post partum or only pre partum, there were no significant differences in the frequencies of A. pyogenes isolated at different seasons. There were geographical differences in bacterial incidence, e.g. Staphylococcus aureus was isolated significantly more often in northern regions whereas Str. dysgalactiae was more common in the south. This and other Swedish investigations support the theory that A. pyogenes and strictly anaerobic bacteria are 'secondary invaders' that depend on Str. dysgalactiae to cause a primary infection. It is stressed that the udders of all heifers should be examined daily so that cases of mastitis can be treated immediately.

Adhesive proteins of haemagglutinating Staphylococcus aureus isolated from bovine mastitis

Two proteins derived from the cell wall of Staphylococcus aureus, exhibiting apparent molecular masses of 116 kDa and 145 kDa, were found to bind to human buccal and bovine lactiferous sinus epithelial cells. By using antibodies specific for fibronectin-binding protein of S. aureus of human origin, the 116 kDa protein, but not the 145 kDa protein, was identified as a fibronectin-binding protein. The 145 kDa protein bound to bovine fat globule membranes, human buccal epithelial cells, bovine lactiferous sinus epithelial cells and sheep erythrocytes. The properties of the 145 kDa protein suggest that it is an adhesin with a possible role in the early stages of the development of bovine mastitis.

Ability of bovine mammary macrophages to enhance proliferation of autologous blood and mammary secretion lymphocytes

Cells were obtained by centrifuging the mammary secretion of healthy udders of 19 cows during the dry-period and during mid-lactation. The suspended cells were incubated in plastic wells. Those adhered cells classified as mammary macrophages were incubated with pokeweed mitogen (PWM). Autologous peripheral blood lymphocytes were added to wells containing untreated macrophage cultures or cultures pretreated with PWM. In seven cows autologous dry-period mammary lymphocytes were added instead of blood lymphocytes. The macrophages + lymphocyte cultures were subjected to the lymphocyte stimulation test (LST). For comparison, peripheral blood lymphocytes and dry-period secretion lymphocytes were also subjected to the LST in the presence of PWM. In all cases, mitogenic responses were higher in pretreated macrophage cultures than in background control cultures. The stimulation indices (SI) showed that PWM-pretreated dry-period mammary macrophages enhanced the proliferation of autologous peripheral blood lymphocytes to a greater extent than did blood lymphocytes plus PWM (49 +/- 10 v. 30 +/- 6; P less than or equal to 0.05). Mammary macrophages taken from the same cows but during midlactation also clearly induced proliferation of autologous peripheral blood lymphocytes but to a lesser extent than dry-period macrophages (16 +/- 2 v. 49 +/- 10; 16 +/- 2 v. 30 +/- 6; P less than or equal to 0.01 and P less than or equal to 0.05). The PWM pretreatment of mammary macrophages increased the proliferation of autologous dry-period mammary lymphocytes by at least a factor of three (28 +/- 8 v. 8 +/- 2 P less than or equal to 0.05). The present results indicate that bovine mammary macrophages pretreated with PWM enhance proliferation as well as modulation of mammary and peripheral blood lymphocytes. The modulation of lymphocyte stimulation as demonstrated here in vitro, has great significance regarding aspects of local immunostimulation related to modern treatment of mastitis.

A preliminary study of uterine derived polymorphonuclear cell function in mares with chronic uterine infections

From 6 mares with chronic uterine infection, polymorphonuclear neutrophils (PMNs) were obtained from the uterus. In order to recover an adequate number of viable PMNs, 0.1% oyster glycogen was infused into the uterus as a mild irritant 12 h prior to the uterine flushing. Phagocytosis and chemotaxis of the uterine derived PMNs were determined. The supernatant from the uterine flushing was compared with autologous serum for its capacity as an opsonin and chemoattractant. There was a significant increase of both phagocytosis and chemotaxis when autologous serum was used compared with the supernatant from the uterine flushing. This study indicates that autologous serum has a greater opsonizing capacity than uterine secretion from mares with chronic uterine infection. Since all mares conceived following this study, the use of oyster glycogen was not considered to have deleterious effect on the uterine mucosa.

Plasminogen activation in the bovine udder

Plasmin is a serin protease with a broad substrate specificity which might cause disintegration of basal membranes, epithelium and surrounding matrix. Plasmin might also elicit degradation of tissue (Mullins & Rohrlich 1983).

Effects of parity and stage of lactation on adenosine triphosphate, somatic cell count and antitrypsin content in cows' milk

Significant effects of parity and stage of lactation were found on ATP content, somatic cell count and antitrypsin content when using morning milk samples from 39 cows over a period of 18 months. A close similarity was evident between variation in ATP and somatic cell count, except during the first 10 d after parturition when the variation in ATP was more pronounced. The same result was obtained in the whole material as well as in a healthy subset. This study shows clearly that parity and stage of lactation must be taken into account when establishing normal values for ATP as an indicator of mastitis.

Studies of defence mechanisms and inflammatory reactions in the bovine teat using a new experimental method

Bovine intramammary infections are usually caused by microorganisms entering through the teat canal. The teat canal normally acts as a mechanical and physiological barrier preventing bacteria from entering the teat cistern. This barrier can be broken, e.g. if the teat end is damaged, making it possible for bacteria to invade the teat cistern. If an infection is established inflammatory reac-tions will occur in the udder.

Comparison of some screening tests for detecting mastitis

Quarter milk samples were analyzed for somatic cell counts, ATP, NAGase, bovine serum albumin, antitrypsin, conductivity, and bacteriological findings. The diagnostic tests were compared with respect to their ability to predict the infection status of a quarter on test day. Predictive ability was evaluated by logistic regression. All components measured increased in the presence of infection. Correlations between components were higher in quarters with pathogens than in quarters free from infection. Predictive ability was highest for ATP, somatic cell counts, and NAGase. Comparisons within udder using ratios from different quarters gave no better prediction than absolute values. For all diagnostic tests except conductivity, combinations of absolute values and interquarter ratios were not better than predictions based on absolute values only. If conductivity is to be used to predict infection status, a combination of absolute value and interquarter evaluation is recommended. Combinations of two diagnostic tests increased the predictive ability in most cases, although the increase was only minor.

Extraction and determination of adenosine 5'-triphosphate in bovine milk by the firefly luciferase assay

The release of ATP from somatic cells in milk with the detergent Triton X-100 was optimized for assay with firefly luciferase. A small volume of milk (40 microliters) is added to 0.8 ml of 0.2% Triton X-100 in 100 mM Tris, 4 mm EDTA, pH 7.8. After approximately 1 min, 0.2 ml of luciferase reagent is added and the emission of light is measured in a luminometer. Results are calibrated with an ATP standard. This single method gave high yields of ATP from somatic cells in milk without interference from bacterial ATP. Extracts could be stored or transported prior to assay without deterioration of results. A close correlation was found between somatic cell count and ATP in milk samples collected at a farm as well as in milk samples from a cow with experimental mastitis. Results are promising for future use for diagnosis of mastitis but further work and field testing has to be done before it can be used on a wider scale.

[Serratia-mastitis in cows as a herd problem]

Clinical mastitis with infection of Serratia marcescens occurred in a tied-up dairy herd in Sweden on a scale widely exceeding what has hitherto been reported in veterinary literature. The herd contained 37 milking cows before the disease period but only 14 at slaughter 21 months later in spite of some recruitment. A very large number of mastitis cases, usually rather mild and of short duration, had then occurred--during one single month not less than 47 cases. Hardly any cow escaped the disease. Instead, the single cows fell ill at short intervals with mastitis in the same quarter as previously or in another quarter. Antibiotic therapy in clinical cases, dry cow therapy and teat dipping had no obvious effect. Serratia marcescens was isolated in all 14 slaughtered cows in one or more quarters. The morphological changes were remarkably mild. Isolated Serratia strains revealed no distinctive marks compared with ordinary saprophytic strains in laboratory tests. Serratia-contaminated sawdust used as litter was possibly the source of infection and the milking machine possibly the tool for the transmission of bacteria to the udder, in the latter case by the aspiration of contaminated sawdust when the claw was attached or detached, or it fell off during milking. The pathogenicity of the bacteria and the susceptibility of the cows to udder infection may have been increased.

The interference between coagulase negative staphylococci and Corynebacterium bovis and the common udder pathogens in the lactating cow

In these experiments it was studied whether the presence of the low pathogenic coagulase negative staphylococci or Corynebacterium bovis in the lactating bovine udder would have a protective effect against some of the common udder pathogens such as Staphylococcus aureus, the streptococci and the Gram negative bacteria.

Characterization and response to mitogens of mammary lymphocytes from the bovine dry-period secretion

From bovine mammary secretion during the dry period, the total number of cells was between 1.2 and 5.9 X 10(6)/ml. A mean of 35% of these cells were classified as lymphocytes and approximately 85% of them could be isolated by the Ficoll-isopac method. Centrifugation separated 6% of the cells into the fat; 5% of them were lymphocytes. About 47% of the lymphocytes bound Helix pomatia agglutinin, a T-cells marker, while the proportion of Ig-bearing cells was approximately 28%. The mammary lymphocytes were stimulated by the lectins phytohaemagglutinin, pokeweed mitogen, concanavalin A and by lipopolysaccharide from Salmonella typhimurium. The stimulation indices of mammary lymphocytes were generally lower than those for peripheral blood lymphocytes from the same animals. The background values, i.e. counts/min of lymphocytes incubated without mitogen, were often higher for lymphocytes isolated from mammary secretion than from blood.

Occurrence and characterization of "avium-like" Mycobacteria isolated from animals in Sweden

431 cultures of "avium-like" mycobacteria (ALM) were isolated from wild and domestic animals during 1974--76 at the National Veterinary Institute, Stockholm. Of these, 50 isolates from pigs were studied by growth-chromogenicity, pathogenicity, and biochemical tests. Furthermore, thin-layer chromathography was performed, and on some isolates serotyping. All 50 isolates belonged to Runyon's group III and were pathogenic for chicken; none was capable of splitting oleic acid from Tween 80. 47 gave tellurite reduction within a period of three days; one was arylsulphatase-positive after three days and a further four after 14 days. The biological and biochemical tests permit assignation of the 50 isolates to the M. avium-intracellulare complex. The lipid patterns of the isolates examined were analysed by thin-layer chromatography. Thirty-five of the isolates showed a lipid pattern similar to that of A 2 of the fowl reference strain; three belonged to lipid type A 1 and four to A 3. Eight could not be typed. Of 22 isolates, 14 could be assigned to M. avium serotypes.

Biochemical characterization of unidentified microaerophilic cocci isolated from heifer and dry-cow mastitis

Thirty-nine strains of gram-positive microaerophilic cocci isolated from cases of heifer and dry-cow mastitis were biochemically characterized with the API 50E and API-ZYM test kit systems, gas-liquid chromatography for analysis of end products of glucose metabolism, and anaerobic biochemical tests (L. V. Holdeman, E. P. Cato, and W. E. C. Moore, Anaerobe Laboratory Manual, Virginia Polytechnic Institute, Blacksburg, 1977). Strains were screened for production of a variety of extracellular enzymes on substrate-containing agar plates and for hemolysin and coagulase production. Antibiotic susceptibility and sensitivity tests were also performed. The microaerophilic cocci displayed homogeneity with respect to the majority of the biochemical tests used; i.e., greater than or equal to 90% of the strains were consistently positive or negative in any one test and probably represent one species. All produced deoxyribonuclease, ribonuclease, and hyaluronidase, and 92% were positive for chondroitin sulfatase. Catalase and coagulase tests were negative. Greening was observed on bovine blood agar. Acetic and succinic acids were produced by all strains as the only detectable products of glucose metabolism. The strains were susceptible to penicillin G, cefoxitin, doxycycline, and chloramphenicol and were resistant to clindamycin, novobiocin, and metronidazole. Their taxonomic position remains unclear.

Phage heterogeneity of coagulase-negative staphylococci isolated in the United States and Sweden from bovine milk

A Swedish bovine and a Dutch human phage set for coagulase-negative staphylococci were used to phage type coagulase-negative staphylococci isolated from bovine milk from Minnesota dairy herds. A comparison was also made of the deoxyribonuclease activity of coagulase-negative staphylococci isolated from bovine milk in Sweden and Minnesota. Of 133 Minnesota isolates, only one could be typed with the Swedish set and one by the Dutch set, whereas of 218 Swedish strains, 49 could be typed with the Swedish set and 7 by the Dutch set. A larger number of coagulase-negative isolates from Sweden were deoxyribonuclease positive (35%) than were the similar isolates from Minnesota (12%). These findings substantiate the marked heterogeneity of coagulase-negative staphylococci isolated from bovine udders. Results presented point to the usefulness of establishing regional phage sets for epidemiological investigations of coagulase-negative staphylococci in cattle. It is anticipated that at a later stage the regional phage sets will be coordinated internationally.

Immunoglobulin-binding structure on bovine group G streptococci different from type III Fc receptors on human group G streptococci

The immunoglobulin G (IgG)-binding capacity of 54 group G streptococci of human and bovine origin was investigated. Of 20 human strains, 17 carried a surface component which could combine with human IgG and bovine IgG1 and IgG2. Inhibition experiments with unlabeled human IgG and with a panel of animal sera revealed that the same surface component was involved in the binding of human as well as bovine immunoglobulins. Of 16 beta-hemolytic bovine group G streptococci, 13 reacted with human IgG but not with bovine IgG1 or IgG2. This binding structure was different from the type III Fc reactivity found in human group G streptococci. All human strains, including the three IgG Fc-nonreactive strains, fermented trehalose, in contrast to all bovine beta-hemolytic strains, which were negative. Immunoglobulin Fc reactivity is thus a feature not only of human strains but also of some bovine strains.

Phage typing of coagulase-negative staphylococci

218 bovine and 116 human strains of coagulase-negative staphylococci and 46 bovine Staphylococcus aureus strains were typed with the Verhoef-phage set for human staphylococci and the Holmberg-set for bovine staphylococci. 22.5% of the bovine strains were lysed by the bovine phages and only 3.2% by the human phages. None of the bovine Staph. aureus strains could be typed. 21% of the human strains tested were lysed by the human phages and only 5.2% by the bovine phages. These results clearly demonstrate the need of separate phage sets for the typing of bovine and human coagulase-negative staphylococci.

The invasiveness of Staphylococcus aureus and Staphylococcus epidermidis for the mammary gland of the mouse

The invasiveness of Staphylococcus aureus and Staphylococcus epidermidis for the mammary gland of the mouse was assessed by contaminating the damaged teats of suckling mice and sampling the mammary glands for the contaminating organism 48 hours later. Using this test system Staphylococcus aureus strain BB invaded 17 of 40 glands (42.5 %) and Staphylococcus epidermidis strain 279 invaded 2 of 40 glands (5.0 %). The histopathological changes in glands infected with Staphylococcus aureus were more severe than in those infected with Staphylococcus epidermidis.