Effects of Certain Variables on the L-Colony Production in Staphylococcus Aureus in the Presence of Methicillin

Abstract

The effect of certain variables on L-colony production in Staphylococcus aureus in the presence of methicillin was studied. All the 20 strains studied produced L-colonies. Two types of solid media were compared. A higher frequency of L-colony production as well as better reproducibility was obtained using a serum-free medium. Using 5-hr bacterial cultures as inocula usually resulted in a 10-fold increase in the frequency of L-colony production compared to 24-hr inoculum. 50% CO₂ in the incubation atmosphere resulted in a lower L-colony production than 5% CO₂. Seven strains producing L-colonies in 5% CO₂ failed to do so in 50% CO₂ on blood agar medium with 24-hr inoculum. One third of the strains producing L-colonies on serum-free medium in a high frequency were found to have low titres of alpha-hemolysin on the same medium. The possibility is discussed that alpha-hemolysin, or a factor associated with alpha-hemolysin production, is a limiting factor for the L-colony production.