Evaluation of the California mastitis test to detect an intramammary infection with a major pathogen in early lactation dairy cows

The purpose of this study was to evaluate the usefulness of the California mastitis test (CMT) to detect an intramammary infection caused by a major mastitis pathogen in early lactation cows. The gold standard used for comparison was bacteriological culture of single milk samples. The sensitivity (82.4%) and specificity (80.6%) of a positive CMT were highest on the 4th day of lactation.     

Non-clinical intramammary infection in lactating ewes and its association with clinical mastitis

A bacteriological survey for the study of non-clinical intramammary infection in the sheep udder was carried out in 88 Assaf ewes. A mean infection prevalence in the first few weeks of lactation was 55%. The most common bacterial isolates were Micrococcus spp. followed by coagulase negative staphylococcus, together accounting for 93% of the total number of isolates. An infection prevalence of 54% was found in ewelambs 2 days after their first lambing, indicating a marked new infection rate around lambing. Generally, the course of lactation was characterized by dynamic changes of new infection and spontaneous resolution. About 5% of half udders examined developed clinical mastitis. The comparison of bacteriological data from mastitic milk samples and from samples taken from the same half udders before the appearance of the clinical disease could not support the theory that in sheep, mastitis is a clinical exacerbation of a non-clinical intramammary infection.     

Application of the California mastitis test in intramammary Streptococcus agalactiae and Staphylococcus aureus infections of camels (Camelus dromedarius) in Kenya

A study was conducted on 207 lactating camels in six herds in Kenya to evaluate the California mastitis test (CMT) for the detection of intramammary infections (IMIs) caused by Streptococcus agalactiae and Staphylococcus aureus and to investigate the prevalence of both the pathogens in the camel udder. IMI with S. agalactiae was found in 12% of all camels sampled. IMI with S. aureus was present in 11% of all camels sampled. The herd-level prevalence of IMI varied between 0 and 50% for S. agalactiae and between 0 and 13% for S. aureus. Longitudinal observations over 10–12 months confirmed persistent infections for both pathogens. Observations in one herd suggested that camel pox was a contributing factor in spreading and exacerbating S. agalactiae udder infections.

The CMT had quarter-level sensitivities of 77 and 68% for S. agalactiae and S. aureus in camels, respectively. The CMT specificities were 91% for both the pathogens.     

Protective effect of previous intramammary infection with Streptococcus uberis against subsequent clinical mastitis in the cow

Following challenge of 23 quarters of 17 lactating cows with 10(3) colony forming units of Streptococcus uberis 0140J, 20 (87 per cent) developed clinical mastitis. Once the disease had resolved each animal was rechallenged in two quarters, one previously challenged and one additional quarter. Of the 34 secondary quarter challenges 11 (32.2 per cent) led to clinical mastitis, a highly significant reduction over the primary challenges.     

The correlation between California mastitis test results and the presence of mastitis pathogens in composite milk samples

Extract

In this, the Ira Cunningham Memorial Lecture, I will not detail all the Professor's achievements. He did so much so well, that I would be hard put to do justice to his record in the time available. What I will do is reflect on his professionalism and on the way he took that professionalism out to work in society.     

The relationship between the California mastitis test, Whiteside test, Brabant mastitis reaction, catalase test, and direct cell counting of milk

The aim of this work was to study the relationship between the reactions obtained by indirect methods of testing milk samples and the cell content, determined by direct cell counting after Prescott & Breed (1910). The indirect tests used were the California Mastitis Test (CMT), Whiteside Test (WsT), Brabant Mastitis Reaction (BMR), and the Catalase Test (CT).The results of the investigations are summarized below.Samples with cell values lying within fixed limits do not neces¬sarily conform to particular indirect test reactions.All four indirect tests have wide ranges of variation of cell level within a given reaction with considerable overlapping between reac¬tions.The standard deviation for cell levels within a given reaction is large, although this can be partly explained by the fact that the cell values are estimated rather than real. Correction for this produces only an insignificant decrease, however.The coefficient of correlation is a little higher for the correlation CMT—CC than for the other indirect tests and CC.When sample groups with different mean cell levels (calculated from the whole material) are compared, the variation ranges (dif¬ference between the largest and the smallest observation) and standard deviations arc generally the same for the different CMT reactions. However, the mean cell values, for different reactions lie at higher levels when the mean cell content of the whole material is higher. Similarly they are lower when the mean of the whole material is lower. This is, however, not true for 0 reactions.The mean cell values for CMT 4- and for 4- 4- reactions varied considerably in different herds.It was not considered acceptable, for any of the four indirect tests, to substitute reactions by average cell values, either to determine the mean cell value or to decide whether a sample is inacceptable, if this means that the sample has a cell content above a certain value.Negative and 4- reactions for CMT and WsT could possibly be replaced by a mean cell level, since the range of variation is not so wide here and the majority of samples giving these reactions contain less than 3xl0⁵ cells per ml.The possibility exists of combining indirect tests and direct cell counting to examine milk samples, so that samples with low reactions could be passed, while those with higher reactions would be examined by cell counting.The indirect tests differentiate milk at different cell levels. The possibility of using a particular indirect test depends on the cell level to be examined and on the degree of accuracy required.     

Interdependence and distribution of subclinical mastitis and intramammary infection among udder quarters in dairy cattle

The objective of the present study was to determine the distribution of subclincial mastitis and intramammary infection (IMI) across udder quarters and to quantify, if any, the level of interdependence between quarters. Subclinical mastitis was defined as an udder quarter somatic cell count of > or =250,000. Intramammary infection was defined as the presence of pathogens in an udder quarter. The data used in the analyses consisted 6577 test-day records from 2034 lactations with observations on subclinical mastitis and 8428 test-day records from 2575 lactations with observations on IMI; each test-day record consisted data on all four udder quarters. Records were from animals on three research herds in southern Ireland. Observed distributions of IMI were compared to expected distributions, estimated using a binomial probability distribution, assuming independence among quarters. Generally, the observed frequencies deviated significantly from the expected frequencies, indicating some level of interdependence between quarters. Intraclass correlations were estimated from a mixed model including cow and test-day record nested within cow as random effects; fixed effects in the model included herd, year of calving, month of calving, parity, days in milk at sampling and interactions. Intraclass correlations within test-day record ranged from 0.14 to 0.50 for subclinical mastitis and from 0.02 to 0.40 for IMI. Thus, substantial interdependence between quarters exists which should be accounted for when analysing data from experiments across udder quarters. Failure to do so may result in incorrect inferences from statistical tests.     

Application of the California mastitis test in intramammary Streptococcus agalactiae and Staphylococcus aureus infections of camels (Camelus dromedarius) in Kenya

A study was conducted on 207 lactating camels in six herds in Kenya to evaluate the California mastitis test (CMT) for the detection of intramammary infections (IMIs) caused by Streptococcus agalactiae and Staphylococcus aureus and to investigate the prevalence of both the pathogens in the camel udder. IMI with S. agalactiae was found in 12% of all camels sampled. IMI with S. aureus was present in 11% of all camels sampled. The herd-level prevalence of IMI varied between 0 and 50% for S. agalactiae and between 0 and 13% for S. aureus. Longitudinal observations over 10–12 months confirmed persistent infections for both pathogens. Observations in one herd suggested that camel pox was a contributing factor in spreading and exacerbating S. agalactiae udder infections.The CMT had quarter-level sensitivities of 77 and 68% for S. agalactiae and S. aureus in camels, respectively. The CMT specificities were 91% for both the pathogens.     

An intramammary implant in the prevention of infectious mastitis in cows

A sterile polyethylene device was introduced in the milk cistern of two mammary quarters of forty dairy cows. The cows were divided into three groups according to the length of exposure of the device in the cistern (3 days, 14 days, 365 days). The somatic cell counts were studied for a year in the first 10 ml fraction of milk and an increase in the somatic cell counts was found in the quarters having the intramammary device, as compared with the control quarters (having no devices). This difference was marked during lactation and prior to the onset of drying off. For the reduction in the frequency of occurrence of new natural intramammary infections, the activity of the device against S. aureus was limited and no activity against S. agalactiae was proved. The proportions of polymorphonuclears, round-cell elements and macrophages were histologically studied and compared for the udder quarters with and without the intramammary body in correlation with the time of exposure of the device to the milk cistern milieu. The most marked differences in favour of the udder quarters with the intramammary device were recorded in the alveoli containing more cells with a significant proportion of polymorphonuclear leucocytes. Small differences were found in the interstitial and subepithelial zone of the milk cistern. The activity of acid and alkaline phosphatase and adenosine triphosphatase was histochemically determined in the tissue structures of the udder and was found not to change under the influence of the device. Leucocytes and macrophages adhering to the surface of the body were observed under scanning electron microscope.     

Ultrastructure and frequency of mastitis caused by ovine progressive pneumonia virus infection in sheep

Twenty-five sheep, experimentally (n = 15) or naturally (n = 6) infected with ovine progressive pneumonia virus and noninfected controls (n = 4), were evaluated for histological and ultrastructural lesions of mastitis. Histologically, nine of 15 experimentally infected sheep and all six naturally infected sheep had lympho-plasmacytic mastitis. Severity of the lesion increased with length of time after infection. Periductal lymphatic nodules were seen in five sheep experimentally infected for 2.8 years or longer and in five naturally infected sheep that were 3.7 years old or older. Ultrastructurally, responses to ovine progressive pneumonia virus were diffuse lympho-plasmacytic infiltrates in glandular interstitium, lymphocytic and occasional plasmacytic infiltrates in ductal walls and lumens, lymphoblasts surrounded by small lymphocytes in glandular interstitium, and degeneration of epithelium releasing cells and cellular debris into the lumen. Based on the prevalence of lesions, the mammary tissue was more susceptible to ovine progressive pneumonia virus than other target organs: lung, brain, and synovium. Lesions did not differ between breeds of sheep. Ovine progressive pneumonia virus was not seen in the mammary tissue but was isolated from 15 of 17 mammary glands.     

The detection of subclinical mastitis in the bactrian camel (Camelus bactrianus) by somatic cell count and California mastitis test

Milk samples (n=160) from 7 clinically healthy bactrian camels were cultured to detect subclinical udder infection. The samples were assessed by the Californian mastitis test (CMT) and somatic cell count (SCC). Bacteria were recovered from 36 (22.5%) of the milk samples. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the main organisms found.Infected quarters had significantly higher mean values for the SCC (p<0.01) and CMT (p<0.001) than non-infected quarters. All 7 camels were infected with CNS but only 4 with S. aureus. CMT values for S. aureus-infected camels were significantly higher than for those only infected with CNS. The values for SCC and CMT were significantly influenced by the stage of lactation (p<0.05). No significant difference was found from the effect of the quarters. Both SCC and CMT were of value in predicting the infection status of the udder.Abbreviations CMT California mastitis test - SCC somatic cell count - CNS coagulase-negative staphylococci     

Detection of capsular polysaccharide in milk of cows with natural intramammary infection caused by Staphylococcus aureus

Detection of capsular polysaccharide (CP) in milk of cows with natural intramammary infection caused by Staphylococcus aureus was attempted. Five quarters of 5 cows harboring S aureus strains that produce type-8 CP were selected. Using an ELISA with a monoclonal antibody, type-8 CP was not detected in extracts prepared from fresh milk collected aseptically. By contrast, CP was easily detectable after incubation of infected milk at 38 C for 20 hours. Quantitation of CP in extracts from incubated milk samples by use of ELISA indicated a great variation of CP expression by strains. Although an incubation step was necessary to detect CP, results of the study indicate that CP may be expressed in vivo during intramammary infection caused by S aureus.     

Resistance patterns of ovine mastitis pathogens]

For control of the udder health status of milk sheep the minimal inhibitory concentration of mastitis causing pathogens to 12 different chemotherapeutics was determined by means of Sensititre microplate method. 73 staphylococci- and 8 streptococci-strains was examined. Following staphylococci-strains were found: S. aureus (11), S. epidermidis (34), S. chromogenes and S. xylosus (6 each), S. hyicus and S. warneri (each 5) as well as S. sciuri and S. simulans (3 each). MIC-values to penicillin, amoxycillin and ampicillin of 2 penicillinase-positive S. aureus-strains were more than 4.0 micrograms/ml. The remaining isolates and the major part of coagulase-negative staphylococci displayed MIC-values up to 1.0 microgram/ml to beta-lactamantibiotics except cloxacillin. Against cephalosporines, cephalexin excluded, and aminoglycosides very low MIC-values concerning staphylococci were observed. In case of spiramycin MIC-levels more or less than 8.0 micrograms/ml were determined. Streptococci exhibited MIC-values in the range of 0.06 to 0.5 microgram/ml against beta-lactamantibiotics with exclusion of cloxacillin, cefoperazone and cefquinome and spiramycin as well.     

Treatment of clinical mastitis: two intramammary formulations compared.

Two hundred cases of mild clinical mastitis were treated on two farms using two intramammary preparations in quick release bases. One preparation contained penicillin and streptomycin, the other contained lincomycin, neomycin and prednisolone. Fifty-eight per cent of cases were clinically and bacteriologically cured using the first preparation; and 61 per cent of cases, with a similar range of organisms, using the second. The main infections were Streptococcus uberis and coliform; all but three of the infections were sensitive in vitro to one or both of the antibiotics in the preparations. On the farm with 100 cows, 69 per cent of cases were cured, while only 52 per cent were cured on the farm with 300 cows. It is suggested that it is more difficult to detect and treat cases in the larger herd. A number of reservations about the interpretation of the results are discussed.     

Use of domestic detergents in the California mastitis test for high somatic cell counts in milk

The California mastitis test (CMT) is used on farms to identify subclinical mastitis by an indirect estimation of the somatic cell count (SCC) in milk. Four commercially available detergents were compared with a bespoke cmt fluid for their ability to detect milk samples with a scc above 200,000 cells/ml; differences between the interpretation of the results of the tests by eight operators were also investigated. The sensitivity and specificity of the test were affected by the type of detergent, and by the operators' interpretations. When used by the most sensitive operator, suitably diluted Fairy Liquid performed almost identically to cmt fluid in identifying milk samples with more than 200,000 cells/ml. The average sensitivities achieved by the eight operators for detecting this threshold were 82 per cent for Fairy Liquid and 84 per cent for cmt fluid, and the specificities were 93 and 91 per cent respectively. The other detergents contained less anionic surfactants and were less sensitive but similarly specific.