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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.
Insights
Culturing L-phase bacteria, which lack cell walls, is challenging. Optimal growth conditions involve specific agar, sucrose, and aerobic incubation, with magnesium crucial for initial broth isolation.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Cell Wall Deficient Bacteria
Background:
- L-phase bacteria, also known as cell wall-deficient variants, pose diagnostic challenges.
- Understanding their culture requirements is crucial for accurate identification and study.
Purpose of the Study:
- To determine optimal conditions for culturing L-phase bacteria.
- To establish a reliable method for routine culture and identification of L-phase organisms from clinical samples.
Main Methods:
- Induced L-phase variants from 13 pathogenic bacterial species using penicillin.
- Inoculated onto various solid and broth media, monitoring growth over 14 days.
- Investigated the effects of agar purity, sucrose concentration, aeration, magnesium, antibiotics, and horse serum on growth and reversion.
Main Results:
- Highly purified agar and sucrose, with aerobic incubation, yielded the best growth on solid media.
- Magnesium was essential for primary isolation in broth but not for subsequent transfers.
- Broth culture proved significantly more difficult than solid media culture.
- Reversion to the normal bacterial form was facilitated by higher agar, lower sucrose, and the absence of antibiotics and horse serum.
Conclusions:
- Established optimal conditions for L-phase bacterial culture, emphasizing specific media components and aerobic incubation.
- Developed a practical procedure for the routine isolation and identification of L-phase bacteria from clinical specimens.
- Highlighted the differential requirements for magnesium during initial isolation versus prolonged culture.