Functional Characterization of the Antibiotic Resistance Reservoir in the Human Microflora

Hidden Pockets of Resistance Groups of bacteria indulge in gene swapping at frequencies correlated with prevailing selection pressures and phylogenetic relatedness. When assaulted by antibiotics, antibiotic resistance genes become favored currency for exchange among bacteria. During sequencing of human gut microflora, Sommer et al. (p. 1128 ) found a very large reservoir of distinct genes that, when put into Escherichia coli , conferred resistance to a wide range of drugs. By contrast, analysis of the culturable aerobic gut microbiome, which constitutes a tiny fraction of the entire gut flora, revealed resistance genes highly similar to those harbored by human pathogens. Although there is a risk of novel modes of antibiotic resistance emerging from this reservoir, because they are evolutionarily distant, gene transfer between pathogens and the poorly known majority of the microbiome might actually be quite restricted.