WHO CO-OPERATIVE STUDIES ON A SIMPLE CULTURE TECHNIQUE FOR THE ISOLATION OF MYCOBACTERIA. 2. COMPARISON OF THE EFFICACY OF LYOPHILIZED LIQUID MEDIUM WITH THAT OF LOEWENSTEIN-JENSEN (L-J) MEDIUM.

This is the second report on a series of co-operative studies undertaken with the object of devising a simplified technique, suitable for use in developing countries, for the isolation of mycobacteria from pathological specimens.The first report described the preparation, reconstitution and properties of a simple lyophilized liquid culture medium. The present report describes three collaborative experiments in which the efficacy of this simple medium was compared with that of Löwenstein-Jensen (L-J) medium. Six national laboratories co-operated in two of the experiments, which were performed according to a special statistical design; and two central and six provincial laboratories took part in the third, which consisted in the routine culture in both media of a large number of specimens.In all but one laboratory, the liquid medium proved to be as good as, or better than, L-J medium, even under tropical conditions, while its contamination rate was in general no higher. There was a large measure of agreement between the results obtained with the two media, although a small proportion of cases could have escaped detection by either. Further, the lyophilized medium did not deteriorate on storage; this, together with its simplicity of preparation and reconstitution, would seem to recommend it for wider use.