Development of L Phase Variants of Neisseria meningitidis and Their Pathogenicity in Experimental Animals.
Annual rept. 1 Oct 70-15 Jun 71,
CHICAGO UNIV ILL
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Work has continued on the development and characteristics of L forms of Neisseria meningitidis with particular emphasis on their stabilization and their potential for deoxyribonucleate transformation of parent meningococci. A review of the incidence of L form development among 80 meningococcal strains isolated between 1966 and 1971 shows that serotype Boshard Y has the greatest potential to produce L form colonies on hypertonic-penicillin medium. Consideration of the source of isolation indicates that strains causing meningococcemia without meningeal involvement have a higher incidence of L form colony production than those isolated from spinal fluid or nasopharynx. Stabilization has occurred among 20 L form strains, including serotypes A, B, C, Boshard Y and RAS. These strains have been adapted to growth in unenriched trypticase soy broth by continuous subculture in decreasing concentrations of agar, horse serum and sucrose. Classic transformation of parent meningococcal strains to streptomycin resistance by deoxyribonucleate of SMr stable L form strains has been confirmed. The results of DNA transformation to L forms have been qualified by the finding that broth cultures of parent meningococcal strains occasionally develop L forms during the stationary phase of the growth curve. Author