Biomedical subjects

C W Pearson

Publications and source records attributed to C W Pearson.

7 recordsLinked to original sources

PubMed1979

Response of cattle to inoculation with atypical mycobacteria isolated from soil.

Nine strains of atypical mycobacteria and a strain of the rhodochrous taxon, originally isolated from soil samples collected on the subcoastal plains of the Northern Territory, were inoculated into cattle. Each strain was injected subcutaneously into one animal and into a mesenteric lymph node of another. At 4 and 10 weeks after inoculation, the cattle were tuberculin tested with bovine PPD tuberculin, avian PPD tuberculin and the appropriate homologous PPD tuberculin. Six strains induced a significant level of sensitivity to bovine PPD at the 4-week test, but only one animal gave a similar response at the 10-week test. In general, the level of sensitivity to all tuberculins declined between the 4-week and 10-week tests. At both tests the response to avian PPD was equal to, or exceeded, that to bovine PPD. The inoculation of each of the 10 strains resulted in the production of tuberculous granulomas at the subcutaneous sites and similar lesions were produced at the mesenteric lymph node site in response to 2 strains. Mycobacteria were re-isolated from 11 cattle and represented 7 strains. The significance of the soil as a reservoir of atypical mycobacteria and other organisms capable of inducing sensitivity to bovine PPD is discussed.

Animals↗

PubMed1978

Pathogenicity for cattle of atypical mycobacteria isolated from feral pigs and cattle and the correlation of lesions with tuberculin sensitivity.

Two experiments involving the inoculation of cattle with atypical mycobacteria are described. In the first experiment groups of 5 cattle were inoculated either subcutaneously or into a mesenteric lymph node with a strain of M. scrofulaceum or M. intracellulare. Four weeks and 10 weeks after inoculation the cattle were tuberculin tested with bovine PPD, avian PPD and homologous PPDs. The pathological changes observed were similar within each group of cattle inoculated with the same strain of mycobacteria. A significant interaction was demonstrated between the strain and the route of inoculation. In the second experiment 17 cattle were similarly inoculated by either of the two routes with 1 of 6 strains of M. intracellulare, a strain of M. scrofulaceum or a strain of Runyon Group IV, all of which had been isolated from feral pigs, or a strain of M. intracellulare of bovine origin. Tuberculin tests were carried out after 4 weeks and 10 weeks. Only the isolate from a bovine lymph node produced a significant level of sensitivity to bovine PPD. Cultural isolation of the mycobacteria from autopsy material was not correlated with the presence of macroscopic lesions nor with sensitivity to bovine PPD. The response to bovine PPD of cattle infected with these atypical mycobacteria decreased between 48 h and 96 h after injection of the tuberculins. As the maximum difference in the response to bovine and avian tuberculins occurs at 72 h a comparative tuberculin test should be read at this time to eliminate non-specific reactors.

Animals↗

PubMed1978

Response of cattle to inoculation with atypical mycobacteria of bovine origin.

Ten strains of atypical mycobacteria originally isolated from cattle were inoculated into cattle. Each strain was injected subcutaneously into one animal and into a mesenteric lymph node of another. Four weeks and 10 weeks after inoculation the cattle were tuberculin tested with bovine PPD, avian PPD and appropriate homologous PPD. Three strains produced a significant level of sensitivity to bovine PPD at the 4-week test but by the 10-week test no animal gave a significant response. The sensitivity to all tuberculins was less at the 10-week test than at the 4-week test. At both tests the response to avian PPD was equal to or exceeded that to bovine PPD. Of 4 strains originally from cattle sensitive to mammalian tuberculin only 2 produced sensitivity of bovine PPD in this experiment. Cultural isolation of mycobacteria from necropsy material was correlated neither with sensitivity to bovine PPD nor with the presence of lesions.

Animals↗

PubMed1977

Anergy to tuberculin in beef cattle.

Various aspects associated with anergy to tuberculin were investigated in a total of 75 tuberculous cattle. Forty-six (59%) had single lesions and 32 (41%) had multiple lesions. Forty-three (55.1%) had lesions in the lungs or associated lymph nodes and 23 (29.5%) showed multiple involvement of these tissues. Nine anergic cattle had generalised tuberculosis. Histological examination of lesions from 38 animals showed that the majority were of the progressive type. When bovine PPD tuberculin was used more cattle were anergic to the 0.1 mg than to the 0.2 mg dose and fewer tuberculous cattle were detected with either dose if tests were read at 96 h rather than 72h. Other factors thought to contribute to anergy are discussed with special reference to its relative importance in cattle with pulmonary infection.

Animals↗

PubMed1977

Serological responses in experimental bovine tuberculosis.

Five two-year-old heifers were each inoculated intravenously with 0.02 mg M. bovis strain AN5. Clinical, haematological and microbiological observations were made during the course of the experiment and antibody levels were measured before and after infection by means of the indirect immunofluorescent antibody (IFA) and bentonite flocculation tests. All cattle developed M. bovis infection varying in severity from peracute tuberculous pneumonia resulting in death within 33 days to chronic progressive generalised tuberculosis. Only cattle developing peracute or acute forms of tuberculosis showed marked haematological changes characterised by leucopenia with lymphopenia. Bacteraemia was detected in the two cattle with peracute tuberculosis 22 days after infection. Anti-mycobacterial antibody was detected after infection in all cattle but fluctuated markedly during the course of the disease. Of a total of 61 serum samples examined from all cattle after inoculation with M. bovis, only 38 were positive to the IFA test and 30 to the bentonite flocculation test. Only 18 were positive to both tests at any one time. IgM was the predominant type of anti-mycobacterial antibody detected by the IFA test and this was found to cross-react with M. avium in almost every sample.

Animals↗

PubMed1977

Tuberculin sensitivity of cattle inoculated with atypical mycobacteria isolated from cattle, feral pigs and trought water.

Each of 12 cattle was inoculated either subcutaneously and intradermally or into a mesenteric lymph node with 1 of 8 species of liver atypical mycobacteria isolated from cattle, cattle trough water and feral pigs. Seventy-eight days after inoculation the cattle were tuberculin tested with bovine PPD, avian PPD and homologous heat-concentrated syntheic medium tuberculins. They were killed 85 days after inoculation. Organisms were cultured from caseous granulomas at all sites in cattle inoculated with M. avium serotype 2. M. simiae was recovered from a granuloma at the subcutaneous site. Acid-fast bacilli were isolated from the mesenteric lymph node inoculated with trough water organisms. At 72 h, all the cattle had produced skin reactions of 4 mm or more to the homologous tuberculins and all except 1 produced a similar response to avian PPD. Only isolates of bovine origin sensitised cattle to bovine PPD to this degree, and these reactions were less than the corresponding response to avian PPD.

Animals↗

PubMed1975

The indirect fluorescent antibody test for the detection of circulating antibodies in bovine tuberculosis.

Indirect fluorescent antibody (IFA) tests were carried out on a total of 545 individual serums from beef cattle just before tuberculin testing, using specific FITC-anti-bovine IgG and IgM conjugates. Phenol-killed M. tuberculosis (H37Rv strain) or field strains of M. bovis and M. avium were used as antigenic substrates. All cattle were examined at abattoirs for the presence of tuberculous lesions. A statistically significant difference (p less than 0.001) was found between the number of cattle with serums containing IgM and those with IgG antibody to M. bovis. The majority of cross-reactions that occurred with M. avium was due to IgM antibody. The IFA test using M. bovis and both antiglobulin conjugates detected 77% of cattle with visible lesions of tuberculosis, while the single intradermal caudal fold tuberculin test detected 83%. The IFA test detected 25 of 31 cattle with lesions that failed to react in the tuberculin test. The tuberculin test gave apparently false positive reactions in 6.2% and the IFA test gave false positive reactions in 21.2% of all cattle. The IFA test is of potential use as a further aid in the detection of tuberculous cattle that fail to react to tuberculin. It offers no advantage over the tuberculin test for the detection of all forms of the disease because it fails to detect a significant proportion of tuberculous cattle and produces an unacceptably high number of false positive results.

Animals↗