The Laboratory Diagnosis of Toxoplasmosis

Cathie, I. A. B.; Dudgeon, J. A.

doi:10.1136/jcp.2.4.259

Cited by 28 publications

(7 citation statements)

References 9 publications

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“…Harboe (1952) reported that only two out of 80 persons tested gave constantly less than 20% modified organisms when their serum was used as accessory factor with negative control sera. Cathie and Dudgeon (1953) reported, " On more than one occasion our so-called normal diluting serum has been shown to have a trace of antibody, sufficient to make the results equivocal." Surveys of large population groups (Hedqvist, 1953;Feldman, 1953Feldman, , 1954Beverley, Beattie, and Roseman, 1954) have shown that fewer children give positive tests for toxoplasmosis than adults.…”

Section: Discussionmentioning

confidence: 99%

“…In trying to set up a routine for running the dye test for toxoplasmosis, it was found that results were often erratic and unpredictable. This has been the experience of other authors in widely different areas (Cathie and Dudgeon, 1953;Lelong and Desmonts, 1952). After taking particular precautions to assure that general laboratory procedures and glassware were not responsible for this situation, it was found that a percentage of routine tests was still erratic and that some had to be discarded because improper results were obtained with control sera.…”

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confidence: 83%

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Observations on Some Problems Encountered in the Routine Performance of the Dye Test for Toxoplasmosis

Goldman¹

1956

Journal of Clinical Pathology

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The dye test for toxoplasmosis (Sabin and Feldman, 1948) depends upon the fact that toxoplasma organisms lose their affinity for methylene blue when they are exposed to specific antibody plus a heat-labile " accessory factor" at present available only from certain human sera. Accessory factor has been shown to differ from complement in several respects. Sera containing antibodies which produce the reaction are said to have " modifying activity" and toxoplasma cells which have been affected by the reaction are referred to as " modified organisms."In trying to set up a routine for running the dye test for toxoplasmosis, it was found that results were often erratic and unpredictable. This has been the experience of other authors in widely different areas (Cathie and Dudgeon, 1953;Lelong and Desmonts, 1952). After taking particular precautions to assure that general laboratory procedures and glassware were not responsible for this situation, it was found that a percentage of routine tests was still erratic and that some had to be discarded because improper results were obtained with control sera.An attempt was made to standardize the toxoplasma suspension which is added to the test sera by washing the organisms obtained from the peritoneal exudate of infected mice and replacing the liquid portion of the exudate with one of known composition.Results obtained in preliminary experiments showed that washed organisms suspended in serumsaline were more sensitive to modification by serum than those suspended in the original exudate. This increased sensitivity was specific in so far as it was apparent only in the presence of active accessory factor. In addition, evidence was obtained that so-called negative human sera used for accessory factor often contained measurable amounts of a modifying substance. This paper presents a description of this work and some observations concerning the dye test as a whole. Materials and MethodsDye test experiments were set up in which three types of toxoplasma suspensions were exposed to human sera in a block test type of arrangement. The percentage of modified organisms in the various tubes of these tests showed, on the one hand, whether the organisms were affected by the suspending media, and, on the other, whether the sera involved had accessory factor and/ or modifying activity. The general method of performing the dye test was based on the procedure recommended by Sabin, Eichenwald, Feldman, and Jacobs (1952).Preparation of Toxoplasma Suspensions.-A barbiturate-buffered saline solution (Kabat and Mayer, 1948) containing, in addition, 0.05%o Na thioglycollate and 10% inactivated human serum which was negative undiluted in the routine dye test was used as the washing and suspending medium for the organisms. The pH of the serum-saline medium was 7.3.To study the effect of washing the organisms, three types of suspensions were used: suspension "A " consisted of toxoplasms in the original exudate. In suspension " B," the toxoplasms were first washed free of the liquid exudate and then were ...

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Section: Discussionmentioning

confidence: 99%

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confidence: 83%

Observations on Some Problems Encountered in the Routine Performance of the Dye Test for Toxoplasmosis

Goldman¹

1956

Journal of Clinical Pathology

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“…This possibility is strengthened by the fact that the Methylgriin of Fehrle (1955) was a thiazine dye, whereas the methyl green used in this study is a triphenyl methane dye. Cathie & Dudgeon (1949) found that the dye solution improved during ageing, and that it retained the ability to stain for 14 days. This was partly confirmed by Gronroos (1955), who found that certain brands of dyes improved on storage at room temperature and all the brands of dyes he examined tolerated storage at room temperature well.…”

Section: Resultsmentioning

confidence: 97%

“…By trial and error they found that a freshly prepared solution of alkaline methylene blue was the best for optimum results. However, Cathie & Dudgeon (1949) observed that a fresh dye solution stained the Toxoplasma so lightly that an accurate evaluation of the stained and unstained Toxoplasma was not easy. They found that an alkaline dye solution which had been matured over 2 days was more suitable and that this solution was serviceable up to 14 days.…”

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confidence: 99%

The indicator system of the Sabin-Feldman phenomenon in Toxoplasma

Kulasiri

1960

Parasitology

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Azure A, azure B and Nile blue in both neutral and alkaline solutions were found to be suitable for use as indicator dyes in the Sabin-Feldman test. Toluidine blue, brilliant cresyl blue and thionine were also suitable as neutral solutions. Azure C, phloxine, phloxine B, neutral red, methyl green, pyronine Y, eosin and celestine blue were found to be unsuitable. Azure B and toluidine blue in saline solutions were serviceable up to 5 months after preparation. The significance of these findings is discussed.

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“…Toxoplasma Suspensions.-The strain of Toxoplasma we use was obtained from Dr. Cathie, who states (Cathie and Dudgeon, 1949) that it was originally isolated by Sabin in 1939 from a child who had acute encephalitis. It is maintained by intraperitoneal passage in mice.…”

Section: Methodsmentioning

confidence: 99%