By Tara Roberts
Injured troops are often exposed to a hidden enemy: infections that become life-threatening when the
bacteria causing them resist treatment with antibiotics.
University of Idaho biology professor Eva Top is seeking to better understand how bacteria retain and
pass on the genes that code for antibiotic resistance, supported by a nearly $1 million, two-year grant
from the U.S. Department of Defense.
“The bottom line is, we have a growing problem of pathogenic bacteria that are resistant to multiple
antibiotics,” Top says.
Scientists have found growing evidence that a major player in this resistance are plasmids – pieces of
genetic material that exist in most bacterial cells outside of chromosomes. Plasmids can rapidly transfer
from bacterium to bacterium, even jumping between species.
Some plasmids have 10 or more antibiotic-resistant genes, Top says.
Top’s research investigates the molecular mechanisms by which drug-resistance plasmids can become
more stable in layers of bacteria known as biofilms, even when no antibiotics are around. Biofilms stick
to surfaces – in this case, the wound. Evidence shows they are more resistant than single, dispersed
Top has studied gene transfer in bacteria for nearly 25 years. She directs the university’s bioinformatics
and computational biology graduate program, and her research falls under the umbrella of the Institute
for Bioinformatics and Evolutionary Studies (IBEST).
IBEST Director Larry Forney is a co-investigator on the Department of Defense grant, as is Matt Settles,
who directs IBEST’s genomic research core. Ann Norton, who directs IBEST’s optical imaging core, also
has a major role in the research.
This study relates to Top’s long-term research, which examines bacteria’s ability to transfer genes
horizontally – cell to cell – via plasmids.
“Many genes form a common pool that bacteria have access to,” she says.
Top’s ultimate goal is to inhibit the spread of plasmids with new antimicrobial agents and other
therapies. If a bacterium’s resistance genes are eliminated, Top says, antibiotics could then be used
effectively – helping patients, whether soldiers or civilians, fight dangerous infections.