Effect of a Staphylococcin on Neisseria gonorrhoeae

Abstract

Phage group 2 staphylococcal strain UT0002 contains a large 56S virulence plasmid with genes that code for both exfoliative toxin and a specific staphylococcin termed Bac R 1 . Four penicillinase-producing strains and three penicillin-susceptible strains of Neisseria gonorrhoeae were killed by Bac R 1 . After 30 min of growth of the penicillin-resistant TR1 strain in 62.5 arbitrary units of Bac R 1 per ml, loss of viability was approximately 90%, and, after 5 h, an approximately 99.99% loss of viability was observed. Lysis did not accompany cell death, and 84% of the Bac R 1 added to the growth medium was adsorbed to the gonococcal cells. The extracellular supernatant fluid from a substrain of staphylococcal strain UT0002 cured of the plasmid for Bac R 1 production had no lethal effect on the gonococcal strains. Bac R 1 was also shown to have bactericidal activity against an L-form of N. meningitidis , indicating that the outer envelope of a neisserial cell is not needed for bacteriocin activity. Ten different normal human sera were unable to neutralize Bac R 1 activity. The bacteriocin lacks adsorption specificity. It binds to but does not kill Escherichia coli cells, indicating that the cell envelope of gram-negative organisms can provide protection against the staphylococcin.