L Form of Neisseria gonorrhoeae

Abstract

Roberts, Richard B. (Walter Reed Army Institute of Research, Washington, D.C.). L form of Neisseria gonorrhoeae . J. Bacteriol. 92: 1609–1614. 1966.—L forms were produced by the penicillin gradient plate technique from a recently isolated strain of Neisseria gonorrhoeae . To date, these L forms have had 30 serial passages on medium containing penicillin. Stabilized L forms developed on penicillin-free medium after 10 or more passages in the presence of penicillin. Morphological characteristics of these organisms were identical to L forms of meningococci. Medium and environmental conditions necessary for optimal growth included: Brain Heart Infusion of p H 7.2 to 7.4, 1.1 to 1.3% agar, 10 to 20% sucrose, 10 to 20% horse serum, temperature at 35 to 36 C, and increased CO 2 tension (candle jar). L forms were more resistant than the parent gonococcus to penicillin, ampicillin, methicillin, cycloserine, and cephalothin, whereas both organisms had similar sensitivities to bacitracin, vancomycin, ristocetin, novobiocin, tetracycline, and erythromycin. Revertant gonococci were produced on penicillin-free medium from L forms which had had 1, 5, and 10 serial passages. Morphology and fermentative reactions of revertant strains were identical to those of the parent gonococcus. Revertant strains produced L forms more readily than the parent organism; in fact, L forms from certain revertants did not require penicillin, but only serum and sucrose for their production and propagation on artificial medium.