Streptococcus spp. comprising Streptococcus (S.) uberis and S. dysgalactiae strains is major cause of bovine mastitis from particularly well-managed or low somatic cell count herds that have successfully controlled contagious pathogens. In this study, antimicrobial susceptibility and genetic characteristics of S. uberis isolated from clinical or subclinical mastitis milk at 2003 were investigated. Eighty seven isolates of Streptococcus spp. were identified by the conventional biochemical methods. The antimicrobial susceptibility by disk diffusion method was determined for 46 S. uberis, 11 S. bovis, 10 S. oralis, 6 S. uberis and 14 other Streptococcus spp., Overall, the tested strains were susceptible to tetracycline (11.5%), amikacin (14.9%), streptomycin (16.1%), neomycin (26.4%), kanamycin (35.6%), gentamicin (65.2%), oxacillin (70.1%), ampicillin (75.9%), chloramphenicol (78.2%), and cephalothin (97.7%).

From July of 1997 to June of 1998, total 279 raw milk samples over wkthdarwal period after mastitis treatment from dairy farms located in the provinces of Kyonggi and Choongchung were collected to test drug residues. Each sample was tested by TTC-II test and Delvotest SP. Among the total 152 raw milk samples of cow treated by beta-lactams, 32 samples(21.2%) were positive on the Delvotest and 15 samples(9.9%) showed positive on the TTC-II test. Also, from the total 37 samples treated by sulfonamides, 5 samples(13.5%) were positive on the Delvotest and 3 samples(8.1%) showed positive on the TTC-II test. For the total 55 raw milk samples of cow treated by tetracyclines, 9 samples(16.4%) were positive on the Delvotest and 5 samples(9.1%) showed positive on the TTC-II test. In addition, from the total 35 samples treated by aminoglycosides, 7 samples(20.0%) were positive on the Delvotest and 5 samples(14.3%) showed positive on the TTC-II test. Our study shows that it is possible that drugs are to be detected by the drug residues test of and individual raw milk even over the withdrawal period after mastitis treatment and the raw milk of bulk tank.

Environmental mastitis has increased particularly in well-managed or low somatic cell count herds that have successfully controlled contagious pathogens. Major pathogens of environmental mastitis are Escherichia coli (E. coli) and Streptococcus uberis. The present study was conducted to investigate the isolation and antibiotic susceptibility of 406 (21.8%) gram-negative bacteria isolated mastitis milk from 1,865 quaters of 241 Korean dairy farms from 2001 to 2004. Prevalence of major gram-negative bacteria isolated from mastitis milk were E. coli (22.7%) and Enterobacter spp. (16.3%) in coliforms and Pseudomoas spp. (10.3%) and Serratia spp. (7.9%) in non-coliforms.

To determine the effects of β-carotene on the control of mastitis in dairy cows during the dry period, 38 dairy cows (18 mastitic cows and 20 healthy cows) were administered with 5ml of β-carotene (30 mg/ml) intramuscularly twice (4 week intervals). Blood samples were taken from the cows before the injection and two weeks after the second injection, respectively, and were measured for the cows before the lymphocyte subpopulations and lymphocyte proliferation responses.

A total of 593 mastitic pathogens was isolated from the clinical mastitic milk of dairy cattle in Kyonggi area from March 1984 to February 1988. The mastitic pathogens were further studied bacteriologically and examined for susceptibility patterns to 10 antibiotics. 173 pathogens were isolated in the first year of studies, 205 pathogens in the second year, 122 pathogens in the third year and 93 pathogens in the last year. The pathogens isolated from clinical mastitis were more in summer than other seasons. Staphylococcus spp (50%) and Streptococcus spp (18%) were the main pathogens in the first year of studies but coliforms (15%) and other bacteria (40%) were the main pathogens in the last year of studies. Coliform mastitis occurred only in summer and autumn. Antibiotic susceptibility patterns of the same genuses from clinical mastitis infections in different herds and in different years varied greatly. Therefore, treatment should be selected on the basis of susceptibility test results

The in vitro activity of penicillins (penicillin G, ampicillin, carbenicillin, methicillin and cloxacillin) and gentamicin to Staphylococcus aureus and coagulase-negative staphylococci isolated from bovine mastitic milk samples was determined. The growth of all isolates of staphylococci tested was inhibited by cloxacillin and methicillin at concentration of 0.78 micro g/ml and by gentamicin at a minimum inhibitory concentration (MIC) of 1.56 micro g/ml

A total of 466 foremilk from dairy farms in Chonnam Korea [R.] district was examined for the subclinical mastitis over a period of 1 year, using a method of the electrical conductivities (EC); absolute conductivity (AC) and differential conductivity (DC) and quarter difference value (QD), in relation to the California mastitis test (CMT) and the direst somatic cell count (DSCC). The compatibility and efficiency rating between the EC values and the other screening tests was conducted

In this study lactating female rabbits and strains of coliforms previously isolated from acute and chronic mastitis cases in dairy cattle were used. The pathological changes on mastitis experimentally induced with the coliform strains and the mammary glands after infusions of Escherichia coli suspension together with dexamethasone, dextran iron or transferrin were grossly and microscopically observed. In the bacterial suspension-infused groups by E. coli, Klebsiella pneumoniae and Enterobacter aerogenes, the affected quarters of udder showed gross swelling, hyperemia, hemorrhage, focal necrosis and firmness

This study was carried out to treatment test for bovine mastitis by the determination of adenosine triphosphate (ATP) based on firefly bioluminescence. In the susceptibility test, cephalothin which looks the most effective were sensitive to Staphylococcus sp. (72.3 %), Micrococcus sp. (84.2 %), Streptococcus sp. (72.7 %) and Gram positive bacilli (72.7 %), Gram negative bacilli were sensitive to gentamycin (92.3 %) and Yeast-like-fungi was the most sensitive to clotrimazole, and nystatin in order. When the number of bacteria, such as Staphylococcus aureus, Candida tropicalis isolated from the mastitis milk were counted by conventional agar plating technique, and compared with the concentration of bacterial ATP, it gave a good linear relationship. The content of ATP per Staphylococcus aureus, cell was 3.1fM and Candida tropicalis showed the high level of ATP (90fM). The ATP assay was applied to the determination of minimal inhibitory concentration (MIC) of various antibiotics. When Staphylococcus aureus was incubated in the presence of different concentration of tetracycline, erythromycin, kanamycin and streptomycin sulfate and the growth was monitored by the conventional agar plating technique and ATP assay, both methods showed the same results that they were 1mcg/ml, 2mcg/ml, 6.25mcg/ml and 8mcg/ml, respectively. For the determination of susceptibility of sensitive and resistant Staphylococcus aureus isolated for the milk with mastitis to tetracycline, erythromycin, kanamycin and strepomycin sulfate, the minimum time required for the test was determined by the assay of ATP every 30 minutes during incubation of 3 hours at 37deg C. ATP concentration time curve calculated on both resistant and sensitive strains incubated 3 hours as the optimum time for the determination of susceptibilities of various antibiotics examed. The ATP concentration of each test brith (antibiotic contraining), expressed as a percentage of its own control brith (antibiotic-free) indicated values of 30 % to be indicative of each antibiotic sensitivity.

This study was carried out to diagnostic test for bovine mastitis by the determination of adenosine triphosphate (ATP) based on firefly bioluminescence. The infection rate of bovine mastitis investigated with 521 cows in 47 dairy farms were found to be 3.6 % of clinical form and 44.1 % of subclinical form according to the degree of infection. The light yield produced in firefly bioluminescence system was proportional to the concentration of ATP giving stright line within the range of 100PM-luM. When the number of somatic cell in milk was determined by the ATP assay and compared with three conventional methods such Fossomatic. California mastatic test (CMT), and rolling ball viscometer (RBV), it was shown that r= 0.92 for Fossomatic, 0.63 for CMT and 0.7 for RBV. The microorganisms causing mastitis were isolated Staphylococcus sp. (53.3 %), Streptococcus sp. (17.9 %), Micrococcus sp. (13.5 %), Gram negative bacilli (6.3 %), Gram positive bacilli (5.5 %) and Yeast-like fungi (5.4 %). The endogeneous ATP levels of bacteria in a raw milk determined by the firefly bioluminescence system and compared with the results of the conventional methods. The correlation was 0.88 for raw milk