Idaho Researchers Aim to Unlock Plasmid Transfer Secrets

Wednesday, June 23 2010

Written by Amanda Cairo

MOSCOW, Idaho – In an effort to take the resistance out of antibiotic-resistant bacteria, University of Idaho researchers are getting down to the genetic level to figure out how multi-drug resistance plasmids increase their resistance.

Thanks to a five-year, $1.7 million grant from the National Institutes of Health, Eva Top, professor of biology, and Zaid Abdo, assistant professor of mathematics and statistics, will study drug resistance plasmids and the range of bacterial hosts in which they can be supported.

“More and more bacteria are becoming resistant to antibiotics, making it more difficult to treat infections,” said Top. “Plasmids play an important role in this spread of drug resistance, and we want to find out what determines the range of bacterial hosts they can move into. Very little is known about the range of hosts to which plasmids can transfer, and if and how that range can change over time.”

Plasmids are little pieces of DNA within a bacterial cell that jump from bacterium to bacterium. As they spread, they bring genetic information into the new cell and can rapidly increase the number of antibiotics to which bacteria are resistant.

Top notes these mobile plasmids can confer resistance to 10 or more antibiotics as they move around. While some plasmids have a narrow range of hosts they can transfer to and stably replicate in, broad-host-range plasmids can transfer and replicate in distantly related bacteria – increasing the resistance spectrum. That is where Top's and Abdo's research will focus and provide a foundation for future opportunities to restrict transfer and spread of resistance.

Spurring the research is a growing trend of bacteria that are becoming resistant to antibiotics, like methicillin-resistant staphylococcus aureus (MRSA) infections that can become life-threatening. In extreme cases, doctors can run out of antibiotics to treat the infection.

“Plasmids have always been around and have carried antibiotic resistance,” she said. “But with the high usage of antibiotics, we need to figure out how the plasmids work before we can fight them.”

Top, Abdo and their teams of students and researchers will be working to unlock the mystery behind plasmids: why do some plasmids multiply with the bacteria and sometimes the transfer doesn’t take place?

With five years of research ahead of them, Top, Abdo and their students will be gaining experience that could ultimately lead to saving hundreds of lives. Their NIH-funded research project is titled "Plasmids as Vectors of Antibiotic Resistance: The Evolution of Plasmid Host Range."
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About the University of Idaho
Founded in 1889, the University of Idaho is the state’s flagship higher-education institution and its principal graduate education and research university, bringing insight and innovation to the state, the nation and the world. University researchers attract nearly $100 million in research grants and contracts each year; the University of Idaho is the only institution in the state to earn the prestigious Carnegie Foundation ranking for high research activity. The university’s student population includes first-generation college students and ethnically diverse scholars. Offering more than 130 degree options in 10 colleges, the university combines the strengths of a large university with the intimacy of small learning communities. The university is home to the Vandals, the 2009 Roady’s Humanitarian Bowl champions. For information, visit

About the University of Idaho
The University of Idaho helps students to succeed and become leaders. Its land-grant mission furthers innovative scholarly and creative research to grow Idaho's economy and serve a statewide community. From its main campus in Moscow, Idaho, to 70 research and academic locations statewide, U-Idaho emphasizes real-world application as part of its student experience. U-Idaho combines the strength of a large university with the intimacy of small learning communities. It is home to the Vandals. For information, visit