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R Higgins

Publications and source records attributed to R Higgins.

At least 163 records · Page 9Linked to original sources
PubMed1988

Electron microscopic examination of capsular material from various serotypes of Actinobacillus pleuropneumoniae.

The capsular material on PPLO broth-grown cells of Actinobacillus pleuropneumoniae representing serotypes 1 to 10 was visualized by transmission electron microscopy after polycationic ferritin labeling and also after stabilization with specific antibodies. All the isolates examined were covered with a layer of capsular material whose thickness varied between 80 to 90 nm and 210 to 230 nm when examined by immunostabilization. We were also able to visualize A. pleuropneumoniae in lungs of infected pigs and to estimate the amount of capsular material covering the cells. Our results indicate that differences in capsular structure exist among the different A. pleuropneumoniae serotypes, and this result may explain in part why the serotypes are not equally virulent.

Actinobacillus↗
PubMed1988

Quantitation of serotype-specific and cross-reacting group-specific antigens by coagglutination and immunodiffusion tests for differentiating Actinobacillus (Haemophilus) pleuropneumoniae strains belonging to cross-reacting serotypes 3, 6, and 8.

There are strong cross-reactions among strains of Actinobacillus pleuropneumoniae belonging to serotypes 3, 6, and 8. Various serological tests were used to differentiate these serotypes from each other. Tube agglutination, coagglutination, and indirect hemagglutination tests were not sufficiently sensitive to differentiate strains of serotypes 3, 6, and 8. However, higher antibody titers were obtained with a 2-mercaptoethanol agglutination test in homologous rabbit antisera. Absorption of immune sera with homologous and heterologous serotypes as well as quantitative estimation of antigenic activity in the unheated and heat-treated bacterial cell suspensions of reference strains with rabbit homologous and heterologous antisera revealed serotype-specific and cross-reacting group-specific antigens. Usually, serotype-specific antigens were major and dominant over group-specific antigens. The coagglutination test could be used quantitatively to measure the ratio of serotype-specific and group-specific antigens with rabbit hyperimmune sera against serotypes 3, 6, and 8. The highest antigen content for a particular serotype reflected serotype-specific antigen. For strains showing equal amounts of antigen for two or more serotypes in the coagglutination test, the immunodiffusion test with boiled cell-saline extract as the antigen and rabbit antisera against whole-cell suspensions of serotypes 3, 6, and 8 clearly revealed the serotype-specific antigen. It is suggested that coagglutination and immunodiffusion tests could be used successfully to determine the exact serotype of strains belonging to serotypes 3, 6, and 8.

Actinobacillus↗
PubMed1988

Serologic studies of Actinobacillus (Haemophilus) pleuropneumoniae strains of serotype-3 and their antigenic relationships with other A pleuropneumoniae serotypes in swine.

Serotype-3 strains of Actinobacillus (Haemophilus) pleuropneumoniae possess epitopes shared with almost all other Actinobacillus serotypes. Common epitopes detected in particulate antigens were heat-labile and heat-stable and were of minor nature. Additional cross-reactive epitopes were detected in soluble and particulate antigens prepared from strains of serotypes 3, 6, and 8. Cross-reactions occurring between serotype-3 antigens and those of other serotypes were of 2 types: one associated mainly with 2-mercaptoethanol (2-ME)-sensitive IgM antibodies and the other associated mainly with 2-ME-resistant IgG antibodies. The cross-reactivity between serotypes 3, 6, and 8 was associated mainly with IgG antibodies, as shown by the results of 2-ME tube agglutination, 2-ME-indirect hemagglutination, and coagglutination tests. None of the tests was entirely satisfactory for serotyping serotype-3 isolates, mainly as a result of overlapping of type-specific antigenic determinants of serotypes 3, 6, and 8 in different combinations in the same strain. A combination of tests, using particulate and soluble antigens, may be necessary for typing of serotype-3 isolates.

Actinobacillosis↗
PubMed1988

Minimal inhibitory concentrations of antimicrobial agents against Actinobacillus pleuropneumoniae.

Forty-five isolates of Actinobacillus pleuropneumoniae were tested for susceptibility to 12 antimicrobial agents using a microdilution method for the minimal inhibitory concentration determinations. These results confirmed the high prevalence of A. pleuropneumoniae strains resistant to antibiotics as reported earlier using the disc diffusion method (Kirby-Bauer method). While 36% of the isolates were resistant to the penicillins, 47% were resistant to chloramphenicol and 68% were resistant to tetracycline. Minimal inhibitory concentrations for the resistant isolates were approximately 32 times higher than those for the susceptible isolates to the above antibacterial agents. The isolates were in general weakly susceptible or resistant to spectinomycin, lincomycin, tiamulin and spiramycin whereas most of them were susceptible to gentamicin, trimethoprim and erythromycin. The susceptibility pattern was similar throughout the 1980 to 1984 period. The 14 serotype 5 isolates were more resistant to tetracycline but less resistant to chloramphenicol and the penicillins than the 28 serotype 1 isolates.

Actinobacillus↗
PubMed1987

Effect of heat treatment on the surface antigens of Haemophilus pleuropneumoniae.

Coagglutination and ring precipitation tests were used to study the effect of heat on the surface antigens of Haemophilus pleuropneumoniae strains employing the reference strains belonging to serotypes 1 to 7 and field isolates belonging to serotypes 1, 2, 3, 5, 6 and 7. By immunising rabbits with formalin-fixed whole-cell suspension, antibodies were obtained which sensitised Cowan I Staphylococcus aureus to coagglutinate antigen preparations which had not been heated, or heated at 56 degrees C, or boiled or autoclaved. Similar positive reactions were obtained with the ring precipitation test. Heating the cultures at 56 degrees C for one hour was best for exposing the most potent serotype-specific antigens in all the strains studied. All the reference strains and most of the field isolates possessed the thermostable type specific antigens which could withstand autoclaving for one hour. However, many field isolates belonging to serotype 1 did not possess this antigen. The apparent antigenic heterogeneity of serotype 1 strains based on the presence or absence of these thermostable antigens could be valuable in epidemiological investigations. It was shown that most potent serotype-specific antigens are present as freely diffusible material on the surface layer of the bacterial cells, which could easily be removed by washing in saline solution. Well washed bacterial cells devoid of surface materials are poor antigens. It is recommended that test strains should not be heated above 56 degrees C for serotyping because higher temperatures are liable to destroy the capsular antigen of some strains and render the culture untypeable.

Agglutination Tests↗
PubMed1987

Isolation of leptospires from nephritic kidneys of beef cattle at slaughter.

Of 955 beef cattle slaughtered at an abattoir in Quebec from May to August 1985, 122 (13%) had lesions of focal interstitial nephritis. Nephritic kidneys were collected for leptospiral culture, and matching blood samples were examined serologically. Leptospires were isolated from the kidneys of 35 (29%) cattle. Antibodies to Leptospira interrogans serovar hardjo were found in 29 (24%) cattle and to pomona in 13 (10%).

Animals↗
PubMed1987

An evaluation of agglutination and coagglutination techniques for serotyping of Haemophilus pleuropneumoniae isolates.

A comparative evaluation of rapid slide agglutination, tube agglutination, 2-mercaptoethanol tube agglutination, and coagglutination tests was made for serotyping isolates of Haemophilus pleuropneumoniae. The results indicated that a majority of the isolates could be serotyped by any of these tests. But, it was not uncommon to find isolates which were inagglutinable or poorly agglutinable in homologous sera. Heat treatment of whole-cell suspensions of such isolates was essential to unmask the serotype-specific antigenic determinants; however, in the process of heat treatment, cross-reactive common antigens of minor nature were also exposed. The antibodies involved in such cross-reactions were mainly of immunoglobulin M type, because the cross-reactivities were completely abolished in coagglutination and 2-mercaptoethanol agglutination tests. Thus, both these tests were satisfactory for serotyping inagglutinable mucoid strains. For serotyping strains which were either polyagglutinating or autoagglutinating, agglutination tests could not be used, but the coagglutination test proved to be satisfactory. The coagglutination test was serotype-specific, sensitive, simple, rapid, reproducible, and easier to read and interpret than rapid slide or tube agglutination tests. This test could be used to serotype mucoid, smooth, or rough isolates.

Agglutination Tests↗
PubMed1986

Biotyping of clinical isolates of Escherichia coli of animal origin, using the Analytab API 20E system.

Using the Analytab (API 20E) Enterobacteriaceae system of biochemical identification, a total of 506 Escherichia coli isolates from different animal species were coded numerically or biotyped. Fifty-four different biotypes were identified, 11 accounting for 83.1% of the isolates examined. Three of these profiles accounted for 65.3% of the isolates and were found in almost all animal species. Some of the biotypes were found in only one animal species: six in cattle, five in horses, 15 in pigs, two in sheep, two in birds, one in dogs and one in a porpoise. Biotypes, as determined here, could not be related to a particular pathology and more work is needed to assess the extent and significance of this relative biotype specificity among animal species. The use of other, more sophisticated, typing systems, i.e. plasmid "fingerprinting", or restriction endonuclease analysis of chromosomal DNA, would have to be investigated.

Animals↗
PubMed1984

Nutritionally variant streptococci from corneal ulcers in horses.

Of 24 isolates of nutritionally variant streptococci recovered from equine corneal ulcers, 22 were tested for growth requirements, physiological and biochemical reactions, and susceptibility to different antimicrobial agents. Satisfactory growth was obtained by supplementing blood agar and Todd-Hewitt broth with pyridoxal hydrochloride, and all of the media for the culture and the biochemical testing were supplemented with 0.002% of this substance. Biochemical patterns of 12 of the isolates resembled those of two viridans streptococcal species, Streptococcus intermedius and Streptococcus constellatus. Patterns of 10 isolates did not resemble those of any recognized viridans species. All of the isolates were inhibited by less than or equal to 0.25 microgram of erythromycin per ml, less than or equal to 4 micrograms of chloramphenicol per ml, and less than or equal to 4 micrograms of gentamicin per ml, and all but two were inhibited by less than or equal to 0.1 microgram of penicillin per ml.

Animals↗
PubMed1984

Serologic studies on brucellosis, leptospirosis and tularemia in moose (Alces alces) in Quebec.

Blood samples were obtained from 208 moose in La Vérendrye and Matane Reserves and in Laurentides Park, Quebec, Canada. Sera were tested for antibodies to Brucella abortus, Leptospira interrogans serovar ballum, canicola, grippotyphosa, hardjo, icterohaemorrhagiae and pomona, and Francisella tularensis. Fifteen sera contained evidence of prior exposure to F. tularensis. Only one animal was a seroreactor to L. interrogans serovar grippotyphosa and none of them had antibodies to B. abortus.

Animals↗
PubMed1984

[Relationship with the patient with bronchopulmonary cancer. Psychological, family and social aspects].

The relationship with a patient suffering from bronchopulmonary cancer is often difficult for the pulmonary physician. This is because of the gloomy prognosis, the unpleasant reputation of the disease, the length of treatment and its efficacy. The quality of life of the patient depends to a great extent on the manner in which he perceives his illness, participates in the treatment and lives through the various stages of this approach till death. The doctor ought to be the guardian of hope, a hope which changes its form and objective as the disease progresses, all of which lead the patient to an understanding of the gravity of the disease and both enables him to talk about it, while maintaining a confident relationship with the doctor. This double requirement of "truth" from doctor and patient should be present from the onset, till the terminal phase. The whole medical team is concerned with this relationship. A conversation with one person may make the patient fear for any therapeutic hopes, and against those objectives which might have tempered the distress which had risen by an impression of therapeutic impotence. With the family communication is also full of tricky points. The principal preoccupation of the doctor is to preserve the relationship established with the patient. This accompaniment demands great availability and above all a lot of time.

Attitude to Death↗
PubMed1984

A 2-mercaptoethanol tube agglutination test for diagnosis of Haemophilus pleuropneumoniae infection in pigs.

A 2-mercaptoethanol (2-ME) tube agglutination (TA) test has been developed as an alternative to the complement fixation (CF) test for the detection of antibodies to Haemophilus pleuropneumoniae, a causative agent of pleuropneumonia in pigs. Using sera from experimentally infected pigs, herds with confirmed H pleuropneumoniae infection, and from disease-free pigs, the specificity and the sensitivity of the 2-ME-TA test were investigated and results were compared with those obtained using the CF test. The TA test without 2-ME gave 100% nonspecific reaction. The 2-ME-TA test was highly specific and more sensitive than was the CF test. Seemingly, the 2-ME-TA test can be used to monitor herds for H pleuropneumoniae antibodies instead of the CF test because it was easier to perform. Test procedures for a presumptive herd diagnosis of H pleuropneumoniae have been proposed.

Agglutination Tests↗
PubMed1983

Determination of antigenic specificity and relationship among Haemophilus pleuropneumoniae serotypes by an indirect hemagglutination test.

Serological properties of antigens extracted from strains of Haemophilus pleuropneumoniae belonging to seven different serotypes were investigated. Antisera were prepared in rabbits against Formalin-treated whole cell suspensions as well as autoclaved cell suspensions. Saline and heat extracts and their alcohol precipitate antigens of H. pleuropneumoniae were used in the indirect hemagglutination test. All the antigens used were easily adsorbed directly onto sheep erythrocytes. Saline extract antigen showed maximum type specificity. Heating of the whole cell suspension revealed the cross-reactive minor antigenic determinants. Thus, the heat extract preparations had both type-specific and species-specific antigens. It is suggested that the indirect hemagglutination test may be useful for both serotyping and serodiagnosis of H. pleuropneumoniae infections in pigs.

Antigens, Bacterial↗
PubMed1983

Identification and serotyping of Haemophilus pleuropneumoniae by coagglutination test.

A coagglutination test for the identification and serotyping of Haemophilus pleuropneumoniae is described. A total of 360 H. pleuropneumoniae strains were isolated from pulmonary tissues of feeder pigs which died of acute pleuropneumonia. All of the isolates were serotyped by coagglutination, and the results were confirmed by the ring precipitation test. The most common serotype isolated in Quebec was serotype 1, followed by serotypes 5, 2, and 7. None of the isolates belonged to serotypes 3, 4, or 6. Mixed infections due to H. pleuropneumoniae of more than one serotype in the same animal were encountered. Serotype 1 was the only common isolate among the mixed-serotype infections. The coagglutination test was more sensitive than was the ring precipitation test. Serotyping by the coagglutination test is inexpensive, rapid, reliable, and easy to perform.

Agglutination Tests↗
PubMed1983

Detection of type-specific antigens in the lungs of Haemophilus pleuropneumoniae-infected pigs by coagglutination test.

Specific diagnosis of Haemophilus pleuropneumoniae infection by the conventional culture and identification method usually requires 3 to 4 days. Since H. pleuropneumoniae may be disseminated from infected individuals during this period, this amount of time required for diagnosis may be too slow to aid in epidemic control. To obtain an earlier diagnosis, a coagglutination test was successfully used to detect serotype-specific antigens in lung extracts of infected pigs. A total of 19 lung tissues from experimentally infected pigs, 240 lung tissues from naturally infected pigs that died of pleuropneumonia, and 571 lung specimens from an apparently healthy pig population were examined for culture isolation as well as for antigen detection. The results showed that detection of antigens in lung tissues by the coagglutination test is an extremely rapid, simple, quite specific, and highly sensitive procedure for the diagnosis of H. pleuropneumoniae infection. Further, detection of antigens in lung tissues was found to be a much simpler and much more rapid method than culture isolation. The coagglutination test seems to be especially useful for detecting H. pleuropneumoniae in pigs exposed to chronic infection as well as those in which multiple serotypes are involved.

Agglutination Tests↗