Infection of the bovine udder with coagulase-negative staphylococci

A commercial dairy herd with a history of chronic staphylococcal mastitis was sampled ten times during a one-year period to determine the pattern of infection with coagulase-negative staphylococci as compared to infection with Staphylococcus aureus.The attack rate (AR) for new infections with S. aureus peaked in March, dropped to a low point in June, and rose again in the autumn. There was no discernible seasonal variation in the AR with the coagulase-negative staphylococci.The prevalence and AR for S. aureus infection increased with advancing age. The AR for new infection with coagulase-negative staphylococci decreased with advancing age.There was no obvious pattern of infection related to stage of lactation with any of the staphylococci isolated.Average duration of infection was longer for S. aureus than for the coagulase-negative staphylococci. Dry period therapy appeared to be more effective in eliminating existing infections with coagulase-negative staphylococci than with S. aureus, but the udder seemed to be equally susceptible to new dry period infections with either category of organism.     

B-mode ultrasonography of the bovine udder and teat

The udders and teats of cows were examined by brightness mode (B-mode) ultrasonography. A 5-MHz linear array transducer and a 5-MHz or 10-MHz mechanical sector transducer were used in the examinations. In lactating animals, the teat sinus, gland sinus, and lactiferous ducts were imaged easily. The scans also allowed visualization of the layers of the teat wall. The annular fold and the folding of the mucosa at the junction of the teat sinus and the papillary duct were seen best with the 5-MHz and 10-MHz mechanical sector transducers. In one cow lacking milk flow from one quarter, a mass at the junction of the papillary duct and the teat sinus was observed ultrasonographically. Surgical removal of the mass resulted in a return of milk flow from that quarter.     

Persistence of staphylococcal species and genotypes in the bovine udder

Staphylococci are a major cause of intramammary infections (IMI) in ruminants. The main aim of this study was to investigate staphylococcal IMI in dairy cattle with emphasis on persistence and distribution of staphylococcal species and genotypes. With a sampling interval of 4-8 weeks, over a year, 4030 samples from 206 cows in 4 herds were collected. Coagulase-negative staphylococci (CNS) and Staphylococcus aureus were detected in 13.2% and 4.2% of the samples, respectively. Selected CNS isolates from quarter milk samples were identified to species level using sodA sequencing. Staphylococcus chromogenes (32%) and Staphylococcus simulans (25%) predominated. The proportion of S. chromogenes was greater in primiparous (52%) than in multiparous cows (12%), while the opposite was the case for Staphylococcus epidermidis (6% and 21%, respectively). Isolates from possibly persistent IMI were selected for pulsed-field gel electrophoresis (PFGE). Six staphylococcal species were found to cause persistent IMI; S. aureus, S. chromogenes, S. simulans, S. epidermidis, Staphylococcus haemolyticus and Staphylococcus warneri. It was shown that several pulsotypes (PTs) within each species were associated with persistent infections, but only a few were spread and caused persistent IMI in multiple cows within a herd. Of special interest was the observation that only one, or a few, strains of each species caused persistent IMI in multiple cows within a same herd. This indicates strain differences with respect to transmissibility and pathogenicity.     

Isolation of bovine herpesvirus-1 from vesicular lesions of the bovine udder

Bovine herpesvirus-1 was isolated from vesicular lesions on the udder and mammary papillae (teats) of a Charolais cow. Lesions on the animal consisted of papules and vesicles up to 10 mm in diameter. The virus was identified by fluorescent antibody and serum-neutralization tests.     

Immune mechanisms of the bovine udder: an overview

Understanding basic defenses of the udder is instrumental in developing measures to prevent mastitis. The teat canal is the first defense against pathogens, providing a physical barrier and antimicrobial substances. When bacteria breach the teat canal, milk leukocytes provide a second defense by ingesting pathogens. Intramammary devices have been used experimentally to increase leukocyte numbers and to enhance destruction of bacteria. Milk antibodies opsonize and lyse bacteria, neutralize toxins, and prevent adhesion to tissue. Vaccinating cows against mastitis generally has been unsuccessful; however, immunization is useful in controlling specific bacterial strains. Antibody-producing plasma cells preferentially accumulate in internal teat end tissues. Because bacteria contact these tissues to reach milk-producing areas of the udder, an immunostimulant to enhance locally the protective nature of plasma cells may decrease the occurrence of infection.     

Changes in the bovine udder quarters naturally infected by Corynebacterium bovis

Of 272 bovine udder quarters studied for mastitis, 19 of them naturally infected with Corynebacterium bovis alone, were compared with 16 others infected by C. bovis together with other bacteria and another 36 non-infected quarters. While there was no significant difference in milk somatic cell counts between the quarters infected by C. bovis alone and those affected by C. bovis together with other bacteria (33.37 +/- 20.28 X 10(3) and 33.86 +/- 23.18 X 10(3)/ml of milk, respectively), there was a significant difference between these and the non-infected quarters (5.60 +/- 3.23 X 10(3)/ml of milk). Microscopically, quarters infected by either C. bovis alone or C. bovis in combination with other bacteria had inflammatory changes in the teat cisterns, Furstenberg's rosettes and/or mammary parenchyma. The non-infected quarters had no changes. In all 82 quarters no pathological changes could be seen in the teat canals.     

Antibacterial effect of bovine lactoferrin against udder pathogens

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.     

Effect of staphylococcal contamination of the bovine udder on milk yield

Zinc sulphate was added to the drinking water of Angus cows and calves grazing an area considered marginal for copper nutrition of cattle. Mean daily intakes of approximately 12–15 mg Zn/kg live-weight further depressed already low plasma copper concentrations to levels considered to indicate copper deficiency. The plasma copper concentrations in untreated animals increased during the trial indicating adequate copper intakes during this period, but the high zinc intakes of treated animals prevented this seasonal rise. Injection of copper glycinate (0.24 g/animal) alleviated the depression of plasma copper associated with the high zinc intakes. The zinc supplements had little effect on plasma zinc concentrations.     

Streptococci from the bovine udder in dairy herds in Khartoum Province, Sudan

Five hundred and seventy-nine milk samples were collected from dairy cows on seven farms in Khartoum North area and one farm in Omdurman and examined by bacteriological cultures for the presence of streptococci. One hundred and ninety-three (33.33%) isolates were recovered and identified on the basis of bacteriological characteristics and biochemical reactions as: S. pyogenes, S. agalactiae, S. dysgalactiae, S. faecalis, S. faecium, S. bovis, S. equi, S. lactis and S. uberis. Fifty-seven isolates representing the preliminary identification were tested by the latex-agglutination test to determine the serological groups. It was found that 39 strains belonged to group B, 3 strains to group C. Four strains gave a weak reaction with group D sera and were identified by biochemical tests as S. uberis. Two isolates could not be identified by the available sera. The isolation of S. uberis, S. bovis, S. equi, S. lactis, S. faecalis, S. faecium and S. pyogenes from cows in the Sudan was reported for the first time.     

Tissue distribution of oxacillin and ampicillin in the isolated perfused bovine udder

In vivo, tissue distribution of intra-mammarily administered antibiotics is mostly only assessed by sampling milk and blood. Therefore, the described study analysed whether measurement of tissue concentrations makes sense in vitro instead. Isolated bovine udders were perfused with gassed and warmed Tyrode solution. To four front and rear quarters each, 1000 mg oxacillin in 7.5 ml vehicle was administered intracisternally, completely formulated as sodium monohydrate in two lactation ointments (with or without sodium dodecylsulphate) or 80% as benzathine salt in a dry-off ointment. Over 3 h, perfusate and glandular tissue from different locations were sampled and analysed by high pressure liquid chromatography. With increasing vertical distance to the teat base, the tissue concentration of antibiotics decreased. With the lactation ointment containing sodium dodecylsulphate, lower oxacillin concentrations were reached in glandular tissue and lymph nodes compared to those without. The ointments led to a higher recovery of oxacillin in glandular tissue than in perfusate. Aluminium monostearate in the dry-off ointment caused an even poorer absorption of oxacillin into perfusate. The isolated perfused bovine udder is suitable to study the tissue distribution of antibiotics, since the results were mainly comparable with the few existing in vivo studies and show the influence of different formulations.