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Biomedical subjects

D M Myers

Publications and source records attributed to D M Myers.

At least 37 records · Page 2Linked to original sources
PubMed1979

Serodiagnosis of ram epididymitis by counterimmunoelectrophoresis, using Brucella ovis surface R antigen.

The counterimmunoelectrophoresis (CIE) technique was developed as a diagnostic procedure for ram epididymitis caused by Brucella ovis. CIE test results with sera from naturally and experimentally infected male sheep compared favorably with those obtained by gel diffusion and complement fixation employing the same B. ovis surface R antigen. The main advantage of CIE over gel diffusion consists in a significant reduction of the time required to detect precipitin formation, whereas both methods obviate several of the difficulties encountered with complement fixation tests for B. ovis.

Animals↗
PubMed1979

Occurrence of antibodies to Brucella canis in rural inhabitants of Corrientes and Neuquén Provinces, Argentina.

Of 1,065 persons sampled during a house-to-house survey of an area of the Department of Curuzú Cuatiá, Province of Corrientes, Argentina, 21 were seropositive to Brucella canis antibodies by the gel-diffusion test, using a saline-extracted B. ovis surface R antigen. Two positive reactors were similarly identified during a survey of rural schools in the Province of Neuquén, which included 887 persons. The findings are discussed in terms of current knowledge of this recently recognized zoonotic infection.

Adolescent↗
PubMed1979

The occurrence of leptospiral antibodies in rural inhabitants of Argentina.

Sera collected during surveys of presumably healthy rural inhabitants of the Provinces of Corrientes and Neuquén, Argentina, were examined for serological evidence of leptospirosis. Significant antibody levels (1:100 or greater) were found in 8.7 per cent of 1,029 sera from residents of Corrientes Province. The most frequent reactions occurred against the serotypes australis, hebdomadis group, pomona, and icterohaemorrhagiae. The predominance of antibodies to the Australis group in the country is new and suggests the emergence of leptospirosis in an unrecognized animal reservoir host. Out of 706 sera collected from rural school students and sera from 71 adults in the Province of Neuquén, only 4 (0.5%) showed leptospiral agglutinin in the microscopic agglutination test and these were only at a 1:100 serum dilution. The higher percentage of reactors in the Corrientes population appears to reflect a more favorable environment and a greater risk of infection.

Adolescent↗
PubMed1978

Broadly reacting precipitating and agglutinating antigen of leptospirae.

A saprophytic Leptospira biflexa strain of equine origin was found which cross-reacts with immune rabbit antisera to 14 pathogenic Leptospira interrogans serotypes. Sera from goats experimentally inoculated with the saprophyte showed multiple low-level cross-agglutination reactions against a battery of live L. interrogans serotypes. Sonically treated and saline-extracted suspensions of the L. biflexa strain and serotypes canicola, icterohaemorrhagiae, and pomona yielded a common precipitating protein antigen that was detected by immunodiffusion and immunoelectrophoresis with all of the antileptospiral sera examined. In cross-absorption and gel diffusion tests, the precipitinogen from each of the strains was shown to be identical. Formaldehyde treatments and heating at 100 degree C suggest that the cellular location of the common antigen is either somatic or subsurface, and Sephadex G-200 gel filtration enabled the isolation of the active fraction of the L. biflexa antigen. Monoprecipitin sera against the common antigen of L. biflexa were produced by immunizing rabbits with specific precipitates in agar. In gel diffusion and immunoelectrophoresis tests the antisera with each of the soluble antigens developed a single precipitin formation, and the antisera agglutinated formolized and heated whole-cell suspensions of serotypes canicola, icterohaemorrhagiae, and pomona at low dilutions. The soluble L. biflexa antigen was evaluated as an immunogen and in passive immunity tests for protection against death and kidney infection in hamsters. No cross-protection occurred when the hamsters were challenged with virulent leptospires. In contrast, the animals vaccinated or administered hamster immune serum before challenge died earlier than the control animals.

Animals↗
PubMed1977

Isolation of serotype hardjo and other leptospirae from armadillos in Argentina.

A serologic, bacteriologic, and histopathologic examination for leptospires was carried out on 89 armadillos (Chaetophractus villosus) from Argentina. Forty-seven per cent of the serum samples yielded positive results when tested by microscopic-agglutination. Predominant agglutination reactions were to the Hebdomadis and Bataviae serogroups. A total of 15 Leptospira isolations (from 16.8 per cent of the animals tested) were obtained from kidney tisse. Nine of the isolates were identified as belonging to the Bataviae group serotypes argentiniensis, paidjan, or bataviae; three other isolates proved to be the Canicola group serotype canicola; two others were Leptospira biflexa strains; and the last isolate was found to be serotype hardjo of the Hebdomadis group. The latter finding represents the first isolation of serotype hardjo from this animal species. Histopathologic examination of kidneys from 11 of the animals yielding pathogenic leptospires permitted a diagnosis of interstitial nephritis. This intersitial nephritis, presenting the characteristic picture of lymphoid infiltration, appeared intense in two animals, moderate in five others, and only slight in the remaining four. These histopathologic findings of chronic nephritis, combined with the high positive serologic and cultural isolation rates, suggest that the armadillo is an important natural reservoir-host for pathogenic leptospirae.

Animals↗
PubMed1976

Serological studies and isolations of serotype hardjo and Leptospira biflexa strains from horses of Argentina.

Three pathogenic leptosipras and 12 saprophytic Leptospira biflexa strains were isolated from 72 apparently normal horse kidneys collected at an abattoir in Argentina. Cross-agglutination reaction patterns of the pathogens showed that they were antigenically homologous with members of the Hebdomadis group. When one of the strains was compared to Hebdomadis serotypes in reciprocal agglutination-absorption tests, it was found to be serologically homologous to serotype hardjo. This is the first known report of an isolation of this serotype from horses. Serological tests were also carried out on randomly collected abattoir sera from 245 horses to determine the prevalence of equine leptospirosis. Significant antibody titers (1:100 or greater) were found in 74.6% of the sera. Predominant reactions occurred with the antigens pomona, hebdomadis group, pyrogenes, tarassovi, and canicola. Agglutination tests performed with antigen prepared with one of the saprophytic biflexa isolates showed seropositive reactions in 99.1% of the equine sera, with agglutination titers ranging from 1:100 to 1:3,200. Absorption of selected horse sera with the saprophytic strain removed the agglutinins to Leptospira interrogans serotypes. This suggests the possibility that L. biflexa strains may act as an antigenic stimulus and account for some of the persistent multiple cross-reaction patterns of equine sera with pathogenic serotypes.

Abattoirs↗
PubMed1975

Efficacy of combined furazolidone and neomycin in the control of contamination in Leptospira cultures.

The in vitro effectiveness of furazolidone combined with neomycin for the control of contaminants in Leptospira cultures was investigated. Enhanced additive or synergistic bactericidal activity was apparent with the combination when it was compared with each agent used separately or when compared with 5-fluorouracil. Combined furazolidone and neomycin, at 5-mug/ml concentrations each in Fletcher medium or in implanted sensitivity disks of 50 mug and 10 mug, respectively, was effective in inhibiting contaminants and did not interfere with the growth of leptospira belonging to 66 leptospiral collection serotypes. A simple technique for decontaminating swine kidneys from an abattoir for cultural isolation of leptospiras is described. The method involves exposing renal tissue diluted in saline containing furazolidone and neomycin in combination (each in a concentration of 25 mug/ml) for 1 h prior to inoculating culture media. The method is suitable for routine use in the isolation of leptospiras from contaminated clinical or pathological specimens.

Drug Combinations↗
PubMed1975

Leptospira fort-bragg isolated from a rat in Barbados.

Leptospira fort-bragg was isolated from the kidney tissue of a rat (Rattus rattus) trapped on a plantation in St. Philip Parish, Barbados. This constitutes the first reported isolation of this Autumnalis group serotype outside of the United States and its first known isolation from an animal species. Serologic evidence is presented which indicates that this serotype may be the cause of leptospiral infections in Barbadian cattle.

Animals↗
PubMed1975

Isolation and identification of leptospira hardjo from cattle in Argentina.

A serological evaluation was done on the prevalence of bovine leptospirosis in Argentina. In 1,857 serum samples obtained from the major cattle raising areas of the country, 59.1 percent showed leptospiral agglutinins in the microscopic-agglutination test. The most frequent leptospiral antigens showing antibody reactions were the hebdomadis group serotypes, of which 45.8 per cent of the sera reacted to Leptospira hardjo with titres ranging from 1:100 to 1:25,600. Six Leptospira isolations were made from 161 bovine kidneys collected at local abattoirs. Their isolation and subsequent identification as serotype L. hardjo is described. This study reports on L. hardjo in cattle of Argentina for the first time and confirms the need for improved cultural methodology for its isolation.

Agglutination Tests↗
PubMed1974

Comparative sensitivity of gel-diffusion and tube agglutination tests for the detection of Brucella canis antibodies in experimentally infected dogs.

The microslide gel-diffusion and macro-tube agglutination techniques to detect Brucella canis antibodies in dogs were compared. Sera from dogs experimentally infected with B. canis and a random sample of dog sera with unknown histories of exposure to this organism were examined. The results of the gel-diffusion method employing specific rough Brucella saline-extract antigens of B. canis and Brucella ovis were comparable to those obtained by the tube agglutination test. The easily prepared, stable R antigen in the freeze-dried form offers a convenient, simple, and reliable diagnostic method for the serological detection of canine brucellosis by the gel-diffusion test.

Agglutination Tests↗
PubMed1973

Procedure for drying leptospiral antibody on sand and sugar for serological studies in leptospirosis.

A simple technique is described for drying sera on washed, dry sand or ordinary sugar cubes for the sero-diagnosis of leptospirosis. The results are shown to be very similar to those obtained with fluid sera or sera dried on filter paper discs. Sera adsorbed on sand or absorbed in sugar eliminated some of the problems associated with sera dried on paper. This method is suitable for use in the field and is expected to be of value in epizootiological studies where contamination and chemical denaturation of fluid serum samples held without refrigeration is a problem.

Agglutination Tests↗
PubMed1973

Long-term survival of Leptospira in a biphasic culture medium containing charcoal.

A comparison was made of the survival of 28 leptospiral serotypes in Fletcher semisolid medium and in the same medium containing a basal layer of Fletcher medium plus 0.7% of agar and 0.5% of activated animal charcoal. A year after culture, more motile leptospires were observed by microscope examination in the biphasic medium. Two years after culture, 4 serotypes grown in the biphasic medium and 11 in Fletcher medium did not show motile cells. Nineteen of the serotypes maintained in Fletcher medium and 25 in the biphasic medium for 2 years grew on subculture into Fletcher medium. Subcultures from the biphasic medium showed the characteristic leptospiral ring growth earlier during the incubation period.

Animals↗
PubMed1973

Selective isolation of leptospiras from contaminated material by incorporation of neomycin to culture media.

Incorporation of neomycin to the culture medium was found to be effective in inhibiting Escherichia coli contaminants without interfering with the growth of serotype L. autumnalis. The growth of 12 other Leptospira serotypes was unaffected by the addition of 300 mug of neomycin per ml to Ellinghausen medium or 5 mug/ml to Fletcher medium. Neomycin-containing medium was found to be of value in the isolation of leptospiras from cultures of blood from infected laboratory animals. A higher percentage of isolates was obtained in swine kidneys from an abattoir in medium containing neomycin than resulted from the same medium without antibiotic or with 5-fluorouracil. Contaminated leptospiral cultures growing in media with 5-fluorouracil were purified by subculturing into neomycin-containing media.

Animals↗
PubMed1973

Field evaluation of the gel diffusion test for the diagnosis of ram epididymitis caused by Brucella ovis.

A comparison was made with the microslide gel diffusion technique, the complement fixation test, cultural isolation, and clinical examination in detecting ram epididymitis caused by Brucella ovis. The results of the gel diffusion method are shown to be similar to those obtained by the complement fixation test and isolation of B. ovis from cultures of semen. The technique offers a reliable diagnostic method adaptable to field use in controlling ovine brucellosis and is more practical.

Animals↗