A new study has demonstrated that at least a quarter of antibiotic-resistant pathogenic bacteria found in clinical settings are capable of spreading their resistance directly to other bacteria.
Researchers obtained 219 clinical isolates of Escherichia coli , all resistant to beta-lactamase. By measuring the rate of plasmid conjugation both with and without beta-lactamase antibiotics present, they showed that, except for one outlier, these antibiotics do not increase the rate of sharing resistance. They also discovered that more than 25% of the strains studied are capable of sharing their resistance at rates fast enough to detect.
"We were surprised to discover that it was that high," said study author Lingchong You. "And of course antibiotics do promote the spread of resistance, but our study indicates that it is primarily through selective population dynamics rather than through an increased rate of plasmid conjugation."
The researchers used a new high-throughput method of measuring the rate at which bacteria exchange the packages of DNA that bestow resistance. The speed and ability to automate much of the process could allow new insights into what variables affect transfer rates, and thus help slow or even reverse the spread of resistance in certain human pathogens, the researchers claim.
The study appears in the journal Science Advances .