LAUSR

A multidrug efflux pump can help bacteria acquire antibiotic resistance through plasmid transfer The spread of antibiotic resistance in bacterial pathogens has become a major public health problem. Resistance genes to clinically relevant antibiotics are often carried on plasmids (circular pieces of DNA) that can be transferred between different types of bacteria through the process of conjugation (1). For example, bacteria that are exposed to antibiotics can survive if they have already received a plasmid with an antibiotic resistance gene from another bacterium. However, how this process of horizontal transfer of resistance genes in the presence of antibiotics works is not entirely clear. Many antibiotics inhibit gene expression, which means that bacteria that have received a plasmid containing an antibiotic resistance gene are unable to express it. On page 778 of this issue, Nolivos et al. (2) describe a mechanism by which bacteria can express resistance genes even in the presence of antibiotics that block gene expression.