L-colony production by different strains of Staphylococcus aureus in the absence of antibiotics.

Abstract

The capacity of 21 strains of Staphylococcus aureus to produce L-colonies in the absence of antibiotics was studied. L-colonies were recovered from different in vitro environments and quantitated on a serum-free solid medium. From six of 21 S. aureus strains suspended in saline, a few L-colonies could be isolated; they grew concomitantly with classical forms of bacteria. Four strains yielding Lcolonies and three other strains were incubated in osmotically stabilized Hanks' solution containing normal rabbit serum and magnesium. L-colonies were recovered only from the first four strains mentioned above, and the growth of L-colonies sometimes dominated over the growth of classical S. aureus. One S. aureus strain had a pronounced tendency for transformation to the L-phase. In long term studies (10 months) large numbers of L-colonies of this strain were isolated from mice with diffusion chambers implanted ip. Some methodologic problems remain in isolation of L-phase variants of S. aureus. Staphylococcus aureus strains in the presence of penicillin or methicillin have different capacities to produce L-colonies [1-3]. However, no report has been published that states how many strains of S. aureus are capable of producing L-colonies in the absence of antibiotics that affect the cell wall.