Spermine impairs biofilm formation by Neisseria gonorrhoeae

Neisseria gonorrhoeae is a strict human pathogen that causes the sexually transmitted infection termed gonorrhea. Recent reports indicate that gonococci can form a biofilm in vivo and under laboratory conditions. It is unclear, however, if formation of such biofilms or their dispersal are influenced by host factors that would be encountered during infection. In this respect, physiological levels of polyamines have been reported to influence biofilm structures formed by other Gram-negative bacteria as well those formed by Gram-positive bacteria and can cause dispersal of a biofilm formed by Bacillus subtilis. Based on these reports, we examined the influence of polyamines on gonococcal biofilm formation and their dispersal. We now report that physiological levels of certain polyamines, notably spermine, can significantly decrease the capacity of gonococci to form a biofilm, but do not cause dispersal of a preformed biofilm. In the context of natural gonococcal infection, the presence of physiological levels of spermine may be antagonistic for gonococci to form a biofilm and this may be of importance in the spread of the pathogen from a localized region.