The roles of sexual and asexual gene transfer in emergence of antibiotic resistant gonococci.

Antibiotic resistance is an increasing problem among gonococci, not only in Asia, Africa and other regions, but also in the U.S.A. Resistance is of two fundamental types: plasmid-mediated, due to production of a beta-lactamase, and non-plasmid-mediated, due to additive effects of chromosomal mutations that decrease antibiotic entry or alter the target site for antibiotic action. Evidence suggests that conjugal (sexual) transfer of plasmids takes place between gonococci in nature, and that asexual transfer by naked transforming DNA may result in transfer of chromosomal resistance genes in nature. Although these events may be relatively rare in vivo, they probably contribute to the ability of the gonococcus to adapt to selective pressure of antibiotics.