People with a past history of even a single skin infection may be three times more likely to develop a surgical site infection when they have an operation, according to new research.

The increased risk suggests underlying biological differences in the way individuals respond to skin cuts that need to be better understood to prevent SSIs, said researchers with Johns Hopkins University.

Even when all of the proper procedures known to prevent SSIs are followed — from administering preoperative antibiotics to using the correct antiseptic to preparing the skin during surgery — some patients appear to be much more susceptible than others to contracting an infection, they noted.

Although the research does not establish a cause-and-effect relationship between a past skin infection and SSI, the researchers said the association is strong and should not be ignored.

"What this research suggests is that people have intrinsic differences in how susceptible they are to infection and that we need to know their skin infection histories," Nauder Faraday, MD, MPH, the study’s lead author and an associate professor of anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine, said in a news release. "Now that we have these findings, we must learn more about the exact molecular basis for the difference and develop new strategies to prevent harm."

Each year, an estimated 500,000 patients in the United States develop SSIs, which are responsible for more than 10,000 deaths, along with disability and decreased quality of life, according to the news release. SSIs also result in longer hospital stays, readmissions and subsequent treatment, and cost the healthcare system billions of dollars a year.

Reducing these complications has become a national priority. The Centers for Medicare and Medicaid Services considers many SSIs to be preventable and has begun to refuse to cover the cost of additional care related to SSIs after certain cardiac and orthopedic procedures.

In the study, Faraday and his colleagues analyzed information before, during and after surgery for 613 patients whose average age was 62. The procedures studied included cardiac surgery, vascular surgery, neurosurgery and spinal surgery, with all patients followed for six months after their operations, which were performed at The Johns Hopkins Hospital and the University of Maryland Medical Center between Feb. 1, 2007, and Aug. 20, 2010. About 22% of the patients had a history of skin infection.

Twenty-four patients developed an SSI within 180 days of surgery, and five died from the condition. Another 15 died from noninfectious causes. Of those who had a history of skin infection, 6.7% suffered an SSI, compared with 3.9% of those without a history of skin disease. Whether the skin infection was recent or had occurred years earlier made no difference. The researchers also adjusted for other known risk factors for SSI, including age, a diagnosis of diabetes and whether the patients were taking certain medications.

An association between a history of skin infection and risk of SSI makes sense, Faraday said. The same types of bacteria that cause skin infections such as abscesses, impetigo or cellulitis, he said, are known to cause wound infections in the operations that were studied. When someone’s immune system responds to exposure to these bugs by developing an infection, the person might have the same reaction when taxed again in a similar way during surgery. Infectious agents can be present or enter even thoroughly cleaned and sterilized hospital environments.

"People are exposed to bacteria and viruses all the time," Faraday said. "Your neighbor may come down with pneumonia and you won’t, even if exposed at the same time to the same germs. Everyone is different and if we treat everyone as though they’re the same, we will never get the risk level to zero."

Faraday said if his results are right and individual differences in biology account for some SSI risk, then penalties imposed on hospitals that fail to prevent SSIs may be at least somewhat premature. "The problem with financial penalties instituted by CMS is that it implies we know everything about how to prevent surgical site infections and if we just do the right thing, we won’t have complications," he said.

"There’s no doubt we can and should do better, but we won’t eliminate infections with the knowledge and treatments we have now. There’s still a lot to learn if we want to reach our goal of zero complications."

The study appeared May 24 on the website of the Annals of Surgery. To read the abstract and access the study via subscription or purchase, visit http://bit.ly/KEkCHN.