Bactericidal antibody in mammalian serum to obligatorily anaerobic Gram-negative bacteria.

A modification has been made of the quantitative photometric serum bactericidal procedure for use with obligatorily anaerobic Gram-negative bacteria. This required the incubation of the serum-sensitive anaerobic bacteria with antibody and complement in an atmosphere containing 95% N-5% CO2. Such a procedure has permitted quantitative determination of bactericidal antibody in various mammalian sera and ascitic fluid to human oral strains of Veillonella and Fusobacterium. Mice immunized intraperitoneally with V. alcalescens in complete Freund's adjuvant developed high titers of bactericidal antibody in both serum and ascitic fluid. Immunization of rabbits with serum-sensitive strains of V. alcalescens produced high titers of specific bactericidal antibody but did not affect the levels of this antibody to serum-sensitive strains of Escherichia coli or Salmonella typhosa. Treatment of human sera with 2-mercaptoethanol and fractionation with Sephadex G-200 indicated that the γM-macroglobulins are responsible for the bactericidal activity to V. alcalescens. Sera from adult patients with periodontal disease when compared to normal adult sera were found to contain increases in bactericidal antibody to F. polymorphum, an organism associated with periodonitis and Vincent's infection.