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1.
Bovine mammary glands were inoculated intracisternally with a streptomycin-resistant (SR) strain of Corynebacterium bovis to determine the number of colony-forming units (CFU) required to induce colonization and to maintain persistence of C bovis colonization throughout lactation and involution. Streptomycin resistance was used as a strain marker. Uninfected quarters in cows during midlactation were challenge exposed with successively higher numbers of SR C bovis until all quarters became colonized. Inoculum containing 790 CFU of SR C bovis established colonization in only 7 of 38 quarters. Colonization persisted in only 4 of these quarters by 23 days after inoculation. Eleven quarters were reinoculated with higher numbers of SR C bovis, and all became colonized by the time challenge-exposure inoculum contained 8 X 10(4) CFU. Colonization persisted throughout the 93-day experimental period. Somatic cell counts were significantly (P less than 0.01) higher in SR C bovis-colonized quarters after inoculation than before. Sixteen additional quarters were inoculated with a mean number of 8 X 10(4) CFU of SR C bovis 7 days before suppression of lactation. All quarters became colonized, and SR C bovis was shed during the experimental period; throughout the nonlactating and peripartum periods, high numbers of SR C bovis in pure culture were shed from 13 of 16 quarters.  相似文献   

2.
In this study, we examined whether an experimental bovine herpesvirus 4 (BHV4) infection can induce bovine mastitis, or can enhance bovine mastitis induced by Streptococcus uberis (S. uberis). Four lactating cows were inoculated intramammarily and intranasally with BHV4, and four lactating control cows were mock-inoculated. After 14 days, two of four cows from each group were inoculated intramammarily with S. uberis. No clinical signs were recorded in cows inoculated only with BHV4, and their milk samples showed no abnormal morphology, despite the fact that BHV4 replicated in inoculated quarters. Somatic cell count increased significantly in milk from three of six BHV4-inoculated quarters, compared to the non-inoculated quarters of the same cows (within-cow) and the quarters of mock-inoculated cows (control group) on days 8, 9 and 11 post-inoculation (pi). BHV4 was isolated from nasal swabs between days 2 and 9 pi. Clinical mastitis was observed in all four cows intramammarily inoculated with S. uberis. A preceding BHV4 infection did not exacerbate the clinical mastitis induced by S. uberis. S. uberis infections appeared to trigger BHV4 replication. From one quarter of each of two cows inoculated with BHV4 and S. uberis, BHV4 was isolated, and not from quarters inoculated with BHV4 only. In conclusion, BHV4 did not induce bovine clinical mastitis after simultaneous intranasal and intramammary inoculation. However, the BHV4 infection did induce subclinical mastitis in 50% of the cows and the quarters.  相似文献   

3.
Mannitol agar for microbiologic diagnosis of bovine mastitis   总被引：1，自引：0，他引：1  
A medium containing mannitol (mannitol agar) was developed and evaluated as a tool for the microbiologic diagnosis of bovine mastitis. Mannitol agar supported growth of all important bacterial mastitis pathogens (staphylococci, streptococci, coliforms, and pseudomonads) except Corynebacterium pyogenes. Color change around colonies in the agar permitted the differentiation of pathogenic from nonpathogenic staphylococci. Most Staphylococcus aureus strains and some Staphylococcus epidermidis strains produced yellow zones. These yellow zone-producing strains (mannitol fermenters) of staphylococci were obtained from quarters with significantly elevated (P less than 0.05) somatic cell counts (SCC) in the milk, as compared with uninfected quarters and, therefore, would be considered pathogens. Mannitol-negative strains of S epidermidis (those with red zones) were obtained from quarters with SCC similar to those of uninfected quarters. The streptococci could be divided into 2 groups on the basis of color change around the colonies: Streptococcus agalactiae, Str dysgalactiae, and group G streptococci produced red zones; Str uberis, Str bovis, and enterococci produced yellow zones. Pathogenic streptococci (Str agalactiae, Str dysgalactiae, Str uberis, and group G streptococci) were obtained from quarters with SCC significantly higher (P less than 0.01) than those of uninfected quarters. Streptococcus bovis and enterococci were obtained from quarters with SCC similar to those of uninfected quarters and were considered nonpathogenic. Pathogenic streptococci were found in much higher concentration than nonpathogenic streptococci and could be differentiated on that basis.  相似文献   

4.
Streptococcus uberis is an important cause of mastitis in dairy cows throughout the world, particularly during the dry period, around the time of calving, and during early lactation. Strategies for controlling S. uberis mastitis have not received adequate research attention and are therefore poorly defined and inadequate. Objectives of the present study were to evaluate the efficacy of extended therapy regimens with pirlimycin for treatment of experimentally induced S. uberis intramammary infections in lactating dairy cows during early lactation and to evaluate the usefulness of the S. uberis experimental infection model for evaluating antimicrobial efficacy in dairy cows. The efficacy of extended pirlimycin intramammary therapy regimens was investigated in 103 mammary glands of 68 dairy cows that became infected following experimental challenge with S. uberis during early lactation. Cows infected with S. uberis in one or both experimentally challenged mammary glands were randomly allocated to three groups, representing three different treatment regimens with pirlimycin, including 2-day (n = 21 cows, 31 mammary quarters), 5-day (n = 21 cows, 32 quarters), and 8-day (n = 26 cows, 40 quarters). For all groups, pirlimycin was administered at a rate of 50 mg of pirlimycin hydrochloride via intramammary infusion. A cure was defined as an experimentally infected mammary gland that was treated with pirlimycin and was bacteriologically negative for the presence of S. uberis at 7, 14, 21, and 28 days after treatment. Experimental S. uberis intramammary infections were eliminated in 58.1% of the infected quarters treated with the pirlimycin 2-day regimen, 68.8% for the 5-day regimen, and 80.0% for the 8-day regimen. Significant differences (P <.05) in efficacy were observed between the 2-day and 8-day treatment regimens. The number of somatic cells in milk decreased significantly following therapy in quarters for which treatment was successful in eliminating S. uberis. However, there was no evidence to suggest that extended therapy with pirlimycin resulted in a greater reduction in somatic cell counts in milk than the 2-day treatment. The S. uberis experimental infection model was a rapid and effective means of evaluating antimicrobial efficacy during early lactation at a time when mammary glands are highly susceptible to S. uberis intramammary infection.  相似文献   

5.
"乳康2号"对奶牛细菌性乳房炎的疗效研究   总被引：2，自引：0，他引：2  
用＂乳康2号＂治疗临床型乳房炎奶牛37头。结果表明,治愈28头,有效6头,无效3头,总有效率为91.89%,平均治疗时间4.7d。对采集的37头奶牛治疗前的42个乳区奶样,进行细菌学检查,有33个乳区检出与乳房炎有关的病原菌,占78.57%。检出病原菌5种,主要为无乳链球菌、停乳链球菌、金黄色葡萄球菌、乳房链球菌和大肠埃希菌。停药后采集33个乳区奶样,结果有14个乳区细菌转阴,细菌转阴率为42.42%。在转阴的病原菌中,大肠埃希菌转阴率最高（100%）,其次是混合感染（60.00%）和乳房链球菌（50.00%）。  相似文献   

6.
The protein X of Streptococcus agalactiae is a surface antigen borne by a high proportion of strains isolated from bovine mastitis. We have tested the capacity of two strains of X-bearing Streptococcus agalactiae to induce mastitis in dairy cows. The reference X-strain (411.07) produced an intramammary infection with local clinical signs in the three inoculated quarters. Another X-bearing strain (443.31) of bovine origin produced infection in all 11 quarters inoculated with only 25 or 85 colony-forming units. In naive cows, strain 433.31 induced less exudation of plasma into the milk, shedding of bacteria, macroscopic alteration, and a lower somatic cell count (SCC) than did the reference strain. Only one quarter spontaneously eliminated the infection before antibiotic treatment 9 days after inoculation.The serum of all the cows contained naturally acquired or induced antibodies to the challenge strain (443.31) and possessed opsonic activity. Before inflammation occurred, the milk was almost devoid of antibody or opsonic activities. The early phase of infection was characterized by rapid multiplication of streptococci in the milk, followed by a sharp drop in bacterial counts concomitant with the onset of inflammation.Three cows immunized with protein X displayed higher SCC and bactericidal activity in milk from the inoculated quarter at the onset of inflammation than non-immunized cows. Two of the three immunized cows underwent an early and transient febrile episode and eliminated the infection.  相似文献   

7.
An inhibitor typing scheme, based on the production of and sensitivity to bacteriocin-like inhibitor substances was used to identify strains of Streptococcus uberis obtained from skin swabs and milk samples of dairy cows. Thirty-nine isolates from one herd were compared, with one isolate examined per site for any sampling day. Eighteen different inhibitor profiles were observed from these isolates. When several isolates were obtained from various skin sites on a cow on the same day, the inhibitor profiles were all different. In three cases, Str. uberis was simultaneously isolated from milk sample and teat surface of the same quarter, but similar inhibitor profiles were only observed for one pair of isolates. Furthermore, when several isolates were obtained by repeated swabbing of a single skin site on a cow on the same day, differences in the inhibitor profiles were again seen. It is likely that numerous strains of Str. uberis are capable of producing clinical mastitis since a comparison of ten isolates obtained from cases of clinical mastitis revealed eight different inhibitor profiles. Monthly sampling (April-November) of eleven cows revealed that Str. uberis could be isolated from the skin of the abdominal wall, medial thigh, udder and teats, but was not isolated from the rectum of any of the cows. Str. uberis was more frequently isolated from the skin and milk samples during the winter when the cows had been dried off, than during the spring and autumn.  相似文献   

8.
OBJECTIVE: To investigate and compare the therapeutic efficacy of dry cow agents containing either cephalonium or cloxacillin within Australian dairy herds. DESIGN: A treatment-control trial. METHODS: Milk from infected quarters of cows with high somatic cell counts in milk on eight Australian dairy farms was cultured to identify bacterial pathogens. Cows were randomly assigned to treatment groups and one group was treated with cephalonium at drying off and the other group was treated with cloxacillin at drying off. Milk samples from infected quarters were collected immediately after calving and were cultured for pathogens. The effect of treatment on bacteriological cure was examined and somatic cell counts from infected cows from the first two herd tests after calving were examined for a treatment effect. On four farms, milk samples were collected for culture from all cases of clinical mastitis identified within the first 7 days after calving. The effect of treatment upon incidence of clinical mastitis after calving was examined. RESULTS: There was no significant difference between treatments on quarter cure rates for new infections, for chronic infections and for infections with Staphylococcus aureus, Streptococcus agalactiae and Streptococcus uberis. Infected quarters treated with cephalonium had a significantly higher cure rate than quarters treated with cloxacillin when Corynebacterium bovis and Staphylococcus epidermids were included as pathogens combined (80.3% versus 70.7%). There was no significant difference between the treatments on somatic cell counts of infected cows at the first two herd tests after calving. There was no difference between treatments on the incidence of clinical mastitis in the first 7 days after calving.  相似文献   

9.
To assess the prevalence and patterns of bacterial isolates, cultures were made from the dry mammary glands of dairy cows in six commercial dairy herds in the UK. Milk samples were taken from all four quarters of 480 cows at drying off and at weekly intervals from 14 days before to seven days after calving. A major mastitis pathogen was isolated from at least one quarter of 220 (45.8 per cent) of the cows and from more than one quarter of 90 (18.8 per cent) of them. During the late dry to calving period, of the 957 quarters with three culture results, a major mastitis pathogen was cultured from 236 (24.7 per cent) quarters of 186 (38.8 [corrected] per cent) cows. The most commonly isolated major pathogen was Escherichia coli, followed by Streptococcus uberis and coagulase-positive staphylococci. There were significant differences between the patterns of isolates from different farms and in different calving months, suggesting that the rate of infection was partially dependent on external conditions. The isolation of E. coli, S. uberis or coagulase-positive staphylococci from a cow during the late dry/periparturient period was associated with an increased risk of that cow being culled in the next lactation. Bayesian general linear mixed models were used to assess the associations between the different bacterial species. The probability of isolating either E. coli or S. uberis was significantly greater when the other organism was cultured in a milk sample; this was also true of coagulase-positive staphylococci and S. uberis. When Corynebacterium species were isolated from a milk sample, the probability of isolating coagulase-positive staphylococci or S. uberis decreased significantly, and when coagulase-negative staphylococci were isolated the probability of isolating coagulase-positive staphylococci was reduced.  相似文献   

10.
In a study involving 56 quarters (14 cows), it was seen that standing estrus did not affect circulating neutrophil and milk somatic cell concentrations, neutrophil phagocytosis, milk production, or occurrence of clinical mastitis. The subcutaneous injection of 17beta-estradiol (E2) (0.05 mg/kg of body weight 2 times daily for 2 consecutive days) did not affect neutrophil phagocytosis or milk somatic cell values. However, a significant increase in circulating neutrophils and a significant decrease in milk production were observed. The injection of E2 was followed by clinical mastitis in 4 uninfected quarters, in 7 quarters infected with Corynebacterium bovis, and in 1 quarter infected with Streptococcus uberis and Escherichia coli.  相似文献   

11.
The aim of this paper was to evaluate the effects associated with intramammary infection (IMI) by a bacterium or a group of bacteria (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, Staphylococci other than S. aureus, and Corynebacterium bovis) on the somatic cell count (SCC) in quarter milk of dairy cows. Papers selected for analysis had to provide SCC values associated with the natural infection in quarters by different bacteria. Sampling for measurement of SCC and determination of the infection had to be done on the same day. Only papers published in English or in French after 1971 were considered. Twenty-one papers fulfilled the selection criteria. The animals sampled, the measurement techniques for SCC and the bacteriological identification, as well as the definition of the infection, all differed widely among the selected studies. The meta-analysis method was used to estimate both the mean SCC (arithmetic and geometric) value and the average increase on SCC of each type of infection. The geometric mean SCC in bacteriologically negative quarters was 68 000 c/mL. In case of IMI, the retained SCC was 357 000, 857 000, 547 000, 1 024 000, 1 151 000, 138 000 and 105 000 c/mL in quarters infected by Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, staphylococci other than S. aureus and Corynebacterium bovis, respectively. The variation factors that could influence these SCC values and the bacteriological results are discussed.  相似文献   

12.
Six cows were inoculated into the mammary gland with eight mycoplasma strains isolated from the genital tract of bulls and two type strains. The milk of cows infected with Mycoplasma bovigenitalium strains isolated from the genital tracts of bulls showed a change in the appearance and contained large quantities of mycoplasmas and specific antibodies. The mastitis was most intense in about 9 days and began to subside in 17 days infection. The type strain of M. bovigenitalium PG11 failed to produce mastitis. On the other hand, the type strain of M. bovis PG45 produced severe mastitis after a 14-day latency period, with the infection spreading to the uninoculated quarters, causing atrophy of the mammary gland, and persisting till slaughter. The sera of all cows that developed mastitis after experimental infection contained high titres of specific antibodies. The two infecting mycoplasma species were recovered from the inner organs and mammary glands of these cows after slaughter.  相似文献   

13.
Ten herds with low somatic cell counts in bulk milk had an incidence of clinical mastitis of only 2.2 per 100 cows whereas 10 other herds with similarly low cell counts had an incidence of 53.6 per 100 cows. The major pathogens in the herds with a high incidence were Escherichia coli, Streptococcus uberis, Staphylococcus aureus and the coagulase-negative staphylococci. The percentage of uninfected quarters in the herds with a high incidence of clinical mastitis was 21.4 per cent compared with 12.2 per cent in the herds with a low incidence of clinical mastitis. The prevalence of coagulase-negative staphylococci, Corynebacterium bovis and Micrococcus species was higher in the herds with a low incidence of clinical mastitis. There was a significant linear relationship between the percentage of uninfected quarters and the incidence of clinical mastitis in the herds with a high incidence of clinical mastitis. In herds with a low incidence of clinical mastitis significantly less teat disinfection after milking was practised. The results suggest that infections with minor pathogens tend to protect cows against mastitis, and that teat disinfection after milking may increase the percentage of uninfected quarters and lead to an increased risk of clinical mastitis in herds with low somatic cell counts in bulk milk.  相似文献   

14.
Streptococcus uberis is the most common environmental mastitis pathogen causing udder inflammations of different severities in dairy cows. The aim of the study was to investigate if the different clinical outcome of mastitis induced by different strains of S. uberis can be reflected in the mammary immune response. Mammary epithelial cells and somatic milk cells were treated with heat inactivated and living S. uberis of strain A and strain B in vitro. Strain A was repeatedly isolated from a chronically infected quarter during 8 months, and persisted in the quarter despite antibiotic treatment. Strain B caused an acute clinical mastitis and was not further isolated after a single antibiotic treatment. Treatment with Strain B induced a more pronounced increase of mRNA-expression of various immune factors (interleukin-8, interleukin-1beta, RANTES, and lactoferrin) in mammary epithelial cells than strain A. In contrast to mammary epithelial cells the response of removed somatic milk cells showed no differences between the stimulation with two S. uberis strains. Tumor necrosis factor-alpha mRNA expression was not differently induced by the two strains. In conclusion, the characteristics of different severities of mastitis that are induced by different S. uberis strains in vivo can also be reflected at the level of the immune response of the mammary gland in vitro.  相似文献   

15.
The short- and long-term treatment efficacy of administrating penicillin for bovine subclinical mastitis during lactation when using intramuscular (IM; 9.5 mg [15,000 IU]/kg bodyweight of benzyl penicillin potassium) injections twice daily for 5 days, or intramammary (IMM; 0.3g [300,000 IU] penethamate hydroiodide) administration once daily for 5 days was compared with a control group receiving no treatment. One hundred and twenty-six cows met the inclusion criteria, which were lack of clinical symptoms, no recent treatment with antimicrobials, and findings of penicillin-sensitive Staphylococcus aureus, Streptococcus dysgalactiae, or Streptococcus uberis in combination with an inflammatory reaction. At follow-up 42-58 days after treatment, the proportion of cows negative for the original infection was significantly higher in IM and IMM groups compared to controls, but the difference between antimicrobial treatment groups was not significant. The udder quarter milk somatic cell count (SCC) was significantly lower at follow-up in IM and IMM groups than in controls, but milk production did not differ between treatments. The culling rate during the 10-month period following treatment was significantly higher in the group treated with IMM penicillin than in the other two groups, but the risk of new mastitis treatments within 10 months did not differ between the three groups. The cure rate was significantly affected by lactation number (lower in older cows), breed (lower in the Swedish Holstein breed), pathogen (lower for S. aureus), and pre-treatment SCC (higher for above average SCC). In conclusion, beneficial long-term effects of antimicrobial treatment during lactation of subclinical mastitis caused by S. aureus, Str. dysgalactiae or Str. uberis were not found in the present study.  相似文献   

16.
Haemophilus somnus: investigations of its potential role in bovine mastitis   总被引：4，自引：0，他引：4  
Mammary glands of 6 lactating Holstein cows were inoculated with Haemophilus somnus strain 43826. Three cows developed chronic mastitis and shed bacteria for up to 1 year. Three cows developed acute gangrenous mastitis, with evidence of bacteremia and endotoxemia. Cows with gangrenous mastitis had lower somatic cell counts early after inoculation in affected quarter secretions compared with those in cows that developed chronic mastitis. Cows with gangrenous mastitis developed hypocalcemia, hypoalbuminemia, azotemia, hyperbilirubinemia, mildly increased serum aspartate aminotransferase and creatine kinase activity, and a marked neutropenia with a degenerative left shift. Histopathologic examination of gangrenous quarters revealed edema, necrosis, and vascular thrombosis with few inflammatory cells. A limited survey failed to recover H somnus from dairy cows with clinical mastitis or from mammary secretions from 41 beef cattle at an abattoir.  相似文献   

17.
Twelve dairy herds that had participated in the Pennsylvania Dairy Herd Improvement Association (DHIA) program for at least 12 months, that had a 12-month mean DHIA somatic cell count greater than 700,000 cells/ml, and that had greater than 25% of lactating cows infected with Streptococcus agalactiae participated in a herd blitz treatment program. Initially, quarter milk samples for bacteriologic culturing were collected from all lactating cows. Subsequently, all cows identified as infected with Str agalactiae were treated, using a commercial penicillin-novobiocin intramammary infusion product. In addition, a herd mastitis management program of postmilking teat dipping and treatment of all cows at the start of the nonlactating period was instituted. Thirty days after the initial herd visit, samples from all lactating cows were again cultured, and cows infected at that time were treated. Twelve months after the initial herd visit, samples from all lactating cows were again cultured. Mean prevalence of infection with Str agalactiae decreased (P less than 0.05) from 23.0% of quarters and 41.6% of cows initially to 3.4% of quarters and 9.3% of cows at 30 days and 1.6% of quarters and 4.2% of cows at 1 year. Mean herd DHIA somatic cell count decreased (P less than 0.05) from 918,000 cells/ml initially to 439,000 cells/ml at 30 days and 268,000 cells/ml at 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
An examination of teat canal swabs established that 51 teat canals out of 68 quarters of machine-milked cows were colonized by Staphylococcus aureus. Only 31 of these quarters yielded milk from which S. aureus could be cultured, and 6 out of the 31 produced milk containing somatic cell counts in excess of 500 000/ml. No inhibitory substances could be detected in milk samples 12 h after 10 mg of sodium cloxacillin had been deposited in the test canal on 1-4 successive occasions. Teat canal swabs and milk sample cultures of the same quarters became and remained bacteriologically negative for at least a week after the last treatment. Six quarters, which according to the International Dairy Federation criteria were suffering from subclinical mastitis, became negative after local teat canal therapy. Scanning electron micrographs of one infected teat canal revealed the presence of cocci in depressions and crevices on the epithelial surface, suggesting that such cocci are not always flushed out into milk samples. Teat canal therapy should make a marked contribution to the control of bovine mastitis.  相似文献   

19.
Thirty-two dairy herds, 16 with low somatic cell counts (LSCC; Dairy Herd Improvement Association 12-month mean herd SCC less than or equal to 150,000 cells/ml) and 16 with high somatic cell counts (HSCC; Dairy Herd Improvement Association 12-month mean herd SCC greater than or equal to 700,000 cells/ml) were evaluated to determine the relationship between the prevalence of mastitis in each herd and each herd's mastitis control and management practices. Once for each herd, duplicate quarter milk samples were collected from the lactating cows, a survey of herd mastitis control, milking hygiene, and management practices of each herd was performed, and milking-machine function was evaluated. Of the 16 herds with LSCC, 2 (12.5%) had Streptococcus agalactiae isolated and 7 (44%) had Staphylococcus aureus isolated. Both organisms were found in all of the herds with HSCC. In herds with LSCC, the mean percentage of quarters infected with Str agalactiae was 0.1%, the mean percentage infected with streptococci other than Str agalactiae was 1.9%, and the mean infected with S aureus was 0.7%. In herds with HSCC, 25.7% of the quarters were infected with Str agalactiae, 3.7% were infected with streptococci other than Str agalactiae, and 7.6% were infected with S aureus. A program of postmilking teat dipping and treatment of all cows at the beginning of the nonlactating period was practiced more frequently in the herds with LSCC (81.3%) than in the herds with HSCC (37.5%). Major differences were not found between the 2 groups of herds in the use of the more common milking hygiene techniques or in the maintenance and functional characteristics of the milking equipment.  相似文献   

20.
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.  相似文献   

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