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Abstract
SUMMARY: Seventeen representative strains of pleuropneumonia-like organisms were investigated to determine whether they could be identified by cultural methods.
The L1 organism was readily identified by its morphology and by its cultural appearances on solid and in fluid and semi-solid media. Differences, depending on whether growth occurred anaerobically, whether growth was smooth or granular and whether a precipitate was formed in horse serum media, served to distinguish most of the other strains.
The requirements of serum and yeast extract for promoting growth and the effect of pH were studied with each strain.
Several strains fermented carbohydrates. Young cultures of some strains reduced methylene blue. Haemolysis around colonies in horse blood agar was noted with some strains; young broth cultures of these strains discoloured suspensions of horse erythrocytes. The factor discolouring erythrocytes was found in filtrates of old cultures of Asterococcus bovis.
Two strains were pathogenic for mice; when recovered after passage they showed no alteration in their nutritional requirements.
The organisms were resistant to penicillin; one strain grew in a medium containing 3000 units/ml.
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