Emergence and Spread of Antimicrobial Resistance: Recent Insights from Bacterial Population Genomics.

Driven by progress of DNA sequencing technologies, recent population genomics studies have revealed that several bacterial pathogens constitute 'measurably evolving populations'. As a consequence, it was possible to reconstruct the emergence and spatial spread of drug-resistant bacteria on the basis of temporally structured samples of bacterial genome sequences. Based on currently available data, some general inferences can be drawn across different bacterial species as follows: (1) Resistance to various antibiotics evolved years to decades earlier than had been anticipated on the basis of epidemiological surveillance data alone. (2) Resistance traits are more rapidly acquired than lost and commonly persist in bacterial populations for decades. (3) Global populations of drug-resistant pathogens are dominated by very few clones, yet the features enabling such spreading success have not been revealed, aside from antibiotic resistance. (4) Whole-genome sequencing proved very effective at identifying bacterial isolates as parts of the same transmission networks.