Selection of Media for the Isolation of Common Bacterial L-Phase Organisms from a Clinical Specimen

Abstract

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. MATERIALS AND METHODS This study made use of 13 strains of bacteria sensitive to penicillin in the range of 1 to 25 units/ml and included 3 strains of Escherichia coli, 2 strains of Proteus mirabilis, 1 Klebsiella, 2 strains, each of coagulase-positive and coagulase-negative staphylococci, 2 strains of enterococci, and 1 beta-hemolytic streptococcus. These organisms were selected because of their availability and their high incidence in infection, and because they represent approximately equal numbers of gram-negative rods and grampositive cocci.

Growth of cell wall-defective variants of Escherichia coli: comparison of aerobic and anaerobic induction frequencies

“…In no case did aerobic incubation increase the induction frequency. These findings conflict with the reports that anaerobic conditions do not benefit the growth of CWD bacteria (9,10,11,13). This disagreement probably stems from other investigators selecting species or strains with a propensity for producing aerobic CWD forms or fortuitously choosing an organism with the qualities of our group I organisms.…”

“…Landman et al (9) obtained a quantitative conversion of Proteus mirabilis and Escherichia coli to L-forms with aerobic incubation. Nimmo and Blazevic (13) reported that the growth rate of previously induced L-forms of E. coli was greater with aerobic incubation. Lederberg and St. Clair (11) reported strain variation in the ability of E. coli to grow as L-form colonies but found no special atmosphere necessary for L-type growth.…”