“Superbug” Research

Groundbreaking Research on “Superbug” CRE by Sifri & Mathers: Epidemiology in Action

Background

Carbapenems, a class of broad-spectrum β-lactam antibiotics, are a treatment of last resort for many bacterial infections, including Escherichia coli (E. coli) and Klebsiella pneumonia. Currently, no new antibiotics exist to combat bacteria that have developed resistance to carbapenems — known as “carbapenem-resistant enterobacteriaceae” or CRE. The spread of the gene that causes resistance to carbapenems, Klebsiella pneumoniae carbapenemase (KPC), is considered a public health threat of global significance.

Responding to a serious outbreak of CRE at UVA Medical Center in 2008 and 2009, ID faculty Costi Sifri, Amy Mathers and colleagues developed a new and faster method to identify and track KPC – an important tool in preventing its spread. Their research was published in the November/December 2011 issue of the online journal mBio, and featured in a USA Today investigative report on hospital-acquired infections (Nov. 2012).

Decoding Deadly Hospital-acquired Infections

UVA Medical Center epidemiologist Costi Sifri calls KPC “perhaps the most important new resistance gene of the millennium,” because of its ability to easily hitch a ride on movable genetic elements called plasmids. As it spreads between pathogens, including E. coli and Klebsiella, it induces carbapenem resistance, making them highly infectious and deadly.

Because carbapenem antibiotics are essential for treatment of many hospital infections, “their potential loss as a reliably effective class of antibiotics is a serious public health threat,” Sifri said. “The more rapidly we can detect CRE and understand movement of the KPC gene in hospitalized patients, the more quickly we can intervene to prevent CRE spread to other patients and other strains of bacteria,” and thus maintain the effectiveness of carbapenem antibiotics.

Through their new test method, Sifri’s research team was able to quickly track the movement of plasmids carrying KPC between bacteria and understand the spread of KPC bacteria at the molecular level. While traditional methods take several weeks or months to do this analysis and can only be performed in specialized research laboratories, the method developed by the UVA team takes only one to two days and can be performed by most modern microbiology labs.

“When you’re in a race against time to halt the spread of these life-threatening infections, the traditional methods of detection and tracking are very difficult and frankly take too long,” said Sifri.

“We developed and successfully used a novel technique to rapidly track the gene’s movement between patients and bacteria,” said Amy Mathers, assistant professor in the division and lead author of the 2011 study. “We were able to show that all cases in a cluster of hospital infections could be traced back to a single patient. Most cases were linked by movement of the KPC gene between different bacteria.” Armed with this information, the research team is working on new strategies and tools to prevent the spread of these highly resistant bacteria to other patients.

Adapted from Dec. 2011 UVA Health System news release by Sally Jones, “Health System Research Aims to Stop ‘Superbugs’ in Their Tracks.” USA Today article available at: http://www.usatoday.com/story/news/nation/2012/11/29/bacteria-deadly-hospital-infection/1727667/