The Molecular Ecology of Antibiotic Resistance Genes in Genital Tract Pathogens

Abstract

Genital tract pathogens resistant to antibiotics are now commonly encountered in many parts of the world. The emergence of such strains may clearly be accounted for, at least in part, by the selection of mutant strains which would have a selective advantage in the face of widespread antibiotic usage. Molecular and genetic analysis of antibiotic-resistant organisms, however, indicates that such an explanation is an over simplification. In many instances genes coding for antibiotic resistance appear highly mobile, being capable of transfer, not only between strains of the same species, but between organisms of differing species or genus. Mechanisms of gene transfer which have been demonstrated in vitro include transformation and conjugal transfer of genes located on plasmids. In addition, antibiotic resistance genes located on transposons may be transferred between DNA molecules (e.g. between plasmid and chromosomal DNA). Genetic analysis indicates, moreover, that some antibiotic resistance genes found in genital tract pathogens may have been acquired from enteric bacteria, or bacteria commonly found in the respiratory tract. These observations clearly demonstrate that the pathogenic flora of the human genital tract comprises a highly complex molecular ecosystem.

Key Words:

• Genital tract
• Pathogens
• Antibiotic resistance