May 11, 2011 -- Bedbugs removed from people seeking care at a Vancouver hospital were carrying drug-resistant MRSA or VRE bacteria, Canadian doctors report.
The patients were residents of Vancouver's Downtown Eastside, an area with high rates of homelessness, HIV/AIDS, and injection drug use.
Because such patients are often infested with bedbugs -- and often show up at the hospital with community-acquired MRSA and VRE skin and soft tissue infections -- Marc G. Romney, MD, wondered whether the bugs might be carrying these drug-resistant germs.
"We decided to crush up the bedbugs and culture them," Romney, a physician at Vancouver's St. Paul's Hospital, tells WebMD. "Surprisingly, we cultured drug-resistant bacteria from all five bedbugs we tested, including MRSA from three and VRE from two."
The bedbugs were found on three patients. Two patients had one bedbug each that tested positive for VRE (vancomycin-resistant Enterococcus faecium), an increasingly common cause of extremely difficult-to-treat infections.
A third patient was carrying three bedbugs that tested positive for MRSA (methicillin-resistant Staphylococcus aureus) -- often called a superbug. MRSA, too, is an extremely drug-resistant bug that can cause lethal infections.
Bedbugs have been blamed for all kinds of diseases, ranging from leprosy to hepatitis B. They've never been shown to be responsible for any kind of infection. Romney is quick to point out that his very preliminary study does not mean bedbugs spread superbugs.
"This does not mean bedbugs transmit resistant bacteria, but it suggests they can carry resistant organisms in or on their bodies," he says.
That's an important point, says bedbug expert Jerome Goddard, PhD, associate professor of entomology at Mississippi State University.
"Mechanical transmission of disease agents by bedbugs or other insects isn't unusual," Goddard tells WebMD in an email exchange. "This involves merely transporting the germs on their body parts or proboscis."
Biological transmission -- such as Lyme disease spread by ticks or malaria spread by mosquitoes -- is very different and much more serious.
"Biological transmission wherein the germ multiplies or develops inside the insect and then somehow makes its way back to the salivary glands for injection upon the next feeding is another story," Goddard notes.
Romney and colleague Christopher Lowe of the University of Toronto suggest that bedbugs might deposit drug-resistant bacteria on the skin when they bite. If a person scratched the bite until it bled, the bacteria on the skin might cause an infection.
Indeed, skin infections with drug-resistant bacteria are common among patients from the Downtown Eastside community. So are bedbugs. But so is injection drug use, an extremely efficient means of getting bacteria under the skin.
Romney says his findings mean more research is needed.
"We'd like to actually go into the shelters, collect some of the bedbugs in concert with a bug expert, and see in a community setting if there is evidence of drug-resistant bacteria carriage in bedbugs collected in the community," he says. "We're also interested in exactly where the bedbugs carry the bacteria. There is a suggestion they can carry it in their salivary glands, but is this the case? We don't know."
Romney and Lowe report their findings in the June issue of Emerging Infectious Diseases, published by the CDC.
Lowe, C.F. and Romney, M.G. Emerging Infectious Diseases, June 2011; published online May 11, 2011.
Jerome Goddard, PhD, associate professor of entomology and plant pathology, Mississippi State University; clinical assistant professor of preventive medicine, University of Mississippi Medical Center, Jackson.
Marc G. Romney, MD, clinical assistant professor of pathology and laboratory medicine, University of British Columbia; and St. Paul's Hospital, Vancouver, Canada.