Antibiotic Resistance and Gene Transfer

The way antibiotic resistance spreads and possible problems from genes transferring have been identified by researchers from the Rowett Research Institute in Aberdeen, in new evidence about the way genes pass from one bacterium to another. The research is presented today, Monday 7 April 2003, by Dr Karen Scott at the Society for General Microbiology’s Annual Meeting in Edinburgh.

“We all have a huge number of different bacteria in our guts,” says Dr Scott of the Rowett Research Institute, “and between them they make up a reservoir of millions of genes which they can exchange with each other. Some of the bacteria are harmless such as the bacteria in live yoghurt, and can live safely with us all the time. But other bacteria such as Salmonella, perhaps just passing through, may make us very ill. Any of these bacteria can readily transfer genes to each other which give resistance to some of our most important antibiotics.”

The ability to pass on genes, which has recently received a lot of attention during debates about the safety of genetically modified organisms, depends on the way the gene is held by the bacteria. If the gene is on a very mobile piece of DNA called a plasmid or a transposon, then the bacteria can exchange it very easily.

“We have recently identified two new tetracycline resistance genes in gut bacteria,” says Dr Scott. “We found them in human and pig samples, and in some disease causing bacteria. The identifying sequences were so similar that we can confidently say that the gene transfers have taken place recently, showing that these genes are passed on all the time.”

“Once we know more about the way these genes are passed on, we will be able to help doctors minimise the risk from spreading antibiotic resistance, and improve the way our current antibiotics are used,” says Dr Scott.