MRSA superbug detected in bed bugs and supermarket meats: Report

By Dr. Ananya Mandal, MDMay 15 2011

MRSA in bed bugs

Scientists have made an alarming discovery. They have found that bedbugs can carry the staph “superbug” MRSA (Methicillin-Resistant Staphylococcus aureus).

This was found by Canadian scientists who detected drug-resistant staph bacteria in bedbugs from three hospital patients from a downtrodden Vancouver neighbourhood. These bed bugs have not been known to spread disease, and there’s no clear evidence that the five bedbugs found on the patients or their belongings had spread the MRSA germ they were carrying or a second, less dangerous drug-resistant bacteria.

Bedbugs can cause itching that can lead to excessive scratching, and that can cause breaks in the skin that make people more susceptible to these germs, noted Dr. Marc Romney, one of the authors of the study released Wednesday by Emerging Infectious Diseases, a publication of the U.S. Centers for Disease Control and Prevention. It’s not clear whether the bacteria originated with the bedbugs or the bugs picked it up from already-infected people. “Even though this is a small study, it suggests that bedbugs may be playing a role in the transmission of MRSA in inner-city populations where bedbug infestations are a problem,” said Romney.

“To the best of my knowledge, we have not seen any research that has proven bedbugs have been able to pass diseases to their human hosts,” says Gail Getty, a research entomologist at the University of California, Berkeley, who specializes in urban pests. “Although they do carry pathogens, there is no single scientific study that has proven a transfer.” Past data show that the hepatitis B virus can survive in bedbugs for six weeks after feeding, but there is no evidence that the bugs are able to transmit disease. “I've been predicting this for years,” says entomologist Dr. Michael F. Potter, a professor at the University of Kentucky, in an e-mail, “seeing how all it takes is a breakage of the skin for infection.”

MRSA in meats

MRSA, a bacteria resistant to common antibiotics, has also been discovered in supermarket meats, and the germ is apparently being introduced by human food handlers, a new study reports.

Although thorough cooking will kill the bacteria, consumers run the risk of infection if they handle meats contaminated with the germ, researchers said. MRSA is common in hospitals and nursing homes, where it can cause serious illness and even death. And so-called “community-acquired MRSA” has become a problem among some high school and college athletes who share equipment; this type of MRSA appears as a skin infection and is usually less serious, according to the U.S. Centers for Disease Control and Prevention. It's the community-acquired MRSA that was found in the meats, the researchers said.

“MRSA has always been found in human patients, but we found this in retail meat, so retail meat can be a reservoir of these bugs,” said study lead researcher Yifan Zhang, an assistant professor in the department of nutrition and food science at Wayne State University in Detroit. “When people handle food, they can get the bugs from the meat if the meat is already contaminated,” she explained. The risk of becoming infected is especially high if you have open cuts or sores on your hands or skin, Zhang added. “When you handle food, especially if you have wounds on your hands, wear gloves to protect yourself from getting MRSA infection,” she said.

For the study, Zhang's team purchased 289 raw meat samples, including 156 beef, 76 chicken and 57 turkey samples, from 30 grocery stores in Detroit from August 2009 through January 2010. The researchers found that 22.5% of the samples were contaminated with S. aureus and six samples tested positive for MRSA. Of the six samples contaminated with MRSA, two were beef, three were chicken and one was turkey, the researchers said.

The report was published in the May 11 online edition of the U.S. Centers for Disease Control and Prevention's journal Emerging Infectious Diseases.

If left untreated, MRSA can cause pneumonia or infections of the skin, blood and joints. The bacteria, once confined to hospitals, have been increasingly found in community settings like locker rooms and gyms. It kills 19,000 Americans each year.