Selection of media for the isolation of common bacterial L-phase organisms from a clinical specimen.

The L-phase of 13 bacteria commonly associated with disease were induced by penicillin and inoculated into various solid and broth media; their growth was recorded for a period of 14 days. Plates containing highly purified agar and sucrose as the stabilizing agent and those incubated under aerobic conditions gave the best results. Magnesium seems to be necessary for growth in broth media on primary isolation, although it may not be necessary on multiple transfers after a more stable state has been reached. Growth in broth media is much more difficult to achieve. Reversion is aided by using a higher concentration of agar in plates, by decreasing the sucrose concentration, and by omitting the antibiotics and horse serum. A procedure has been outlined for the routine culture and identification of L-phase organisms from a clinical specimen.