Effective treatment for MRSA only a coin toss

Since the early 1960s, a bacteria called Methicillin-resistant Staphylococcus aureus (MRSA) has raised public health concerns in hospitals across the U.S. These bacteria can cause serious infections in patients with already weakened immune systems: It is estimated that 18,000 people die every year from MRSA-acquired infections.

Ten years ago, Hopkins teamed up with a network of community hospitals to assess and combat the spread of MRSA infections. By training the hospital staff to standardize patient databases and better track infections, researchers hoped that patient outcomes would improve. More recently, however, researchers found that in the 10 hospitals examined, the probability that patients would receive appropriate therapy for blood stream infections due to MRSA was "no better than a coin toss."

Most MRSA infections are found in the skin and soft tissues. The infection begins as a fever and the appearance of small red bumps on the skin. If untreated, the infection can spread to vital organs, causing serious complications such as blood poisoning, toxic shock syndrome or pneumonia. Organ failure and death can follow. MRSA is a serious issue in hospital settings, where many people have weakened immune systems and the bacteria can be easily transferred by hospital workers moving from patient to patient. Additionally, MRSA has earned a reputation as a superbug that is resistant to multiple antibiotics.

"We have seen more and more bacteria which have acquired a protein which allows them to thrive in the presence of antibiotics," head researcher Carrie Herzke said. The DNA that codes for the protein that allows this resistance is easily passed from one strain of MRSA bacteria to another, which can lead to dangerous infections that do not respond to an increasingly long list of antibiotics.

"The concern is both that MRSA represents an immediate threat by causing more severe disease than the non-resistant strains and also that these infections will over time develop resistance to all our available antibiotics," Herzke said.

To acquire data about MRSA risk, infection and treatment, Herzke teamed up with the Duke Infection Control Outreach Network, a network of hospitals in North Carolina that focus on improving hospital infection control. Previous studies have focused on educating hospital staff members, but a recent paper published in November's issue of Infection Control and Hospital Epidemiology focused on the treatment of patients across 10 hospitals who had blood stream infection (BSI) due to MRSA. Among hospitalized patients, this bacterium causes about 20 percent of all BSIs. Researchers wanted to quantify the probability that patients with BSIs due to MRSA would receive suitable therapy. Researchers defined this as the acquisition of one or more appropriate antimicrobial agents "within one calendar day after the first blood culture result positive for S. aureus." Over 550 patients were enrolled in the research, which makes it the largest study to examine risk factors for BSIs due to MRSA.

Researchers found that two patient populations with a well-known high risk for BSIs due to MRSA were given appropriate treatment: patients who arrived at the hospital with a central venous catheter and patients who had recently undergone surgical reconstruction of joints. However, researchers also found that patients who had central venous catheters inserted during hospitalization (versus arriving with one at admission) were not accurately recognized as high-risk.

Similarly, patients with bowel incontinence at the time of hospital admission were less likely to receive appropriate care. This may have been due to physicians attributing the primary source of infection to the bowel or bladder rather than the bloodstream.

As researchers are able to pinpoint which patients at high-risk for MRSA are not given suitable therapy, BSIs due to MRSA should become less prevalent.

"It is our hope that this data will encourage physicians to continue to be vigilant for MRSA infections," Herzke said.