Skin history tied to infection after surgery

Surgical patients who have had even a single skin infection may be three times more likely to develop a painful, costly—and potentially deadly—post-operative infection, researchers report. The increased risk, described online in the Annals of Surgery, suggests there are underlying biological differences in the way individuals respond to skin cuts that need to be better understood in order to prevent surgical site infections, or SSIs, the researchers say. Each year, an estimated 500,000 patients in the United States develop infections at or near the surgical wound from a recent operation, along the incision path into the body or at the organ or body part that was the target of the surgery. SSIs are responsible for more than 10,000 deaths and for disability and decreased quality of life. They result in longer hospital stays, readmissions and subsequent treatment, and they cost the health care system billions of dollars a year. Even when procedures known to prevent SSIs are followed—like administering preoperative antibiotics or using antiseptic to prepare the skin for surgery—some patients appear to be much more susceptible than others to contracting an infection, they add. Although the research does not establish a cause-and-effect relationship between a past skin infection and SSI, the research team says the association between them 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,” says study leader Nauder Faraday, an associate professor of anesthesiology and critical care medicine at Johns Hopkins University. “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.” Faraday and his colleagues analyzed information from before, during and after surgery for 613 patients, with an average age of 62. Their operations included cardiac surgery, vascular surgery, neurosurgery and spinal surgery; all were followed for six months after their procedures, performed at the Johns Hopkins Hospital and University of Maryland Medical Center from February 2007 to August 2010. Some 22 percent 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 percent got an SSI, compared with 3.1 percent of those without a history of skin disease. It made no difference whether the skin infection was recent or had occurred years earlier. After controlling for other known risk factors for SSI—among them a patient’s age and medications or a diagnosis of diabetes—the researchers concluded that surgical patients with a skin infection history are 3.4 times more likely to develop SSI than those without a previous infection. Faraday says it make sense that someone who had a past skin infection would be more likely to get an infection after surgery. Bacteria that cause such skin infections as abscesses, impetigo, or cellulitis, he says, are the same types of bacteria known to cause wound infections in the operations that were studied. After someone’s immune system responds to these bugs by developing a skin infection, it makes sense that 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 says, but even those exposed to the same pathogens respond differently. “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 says if his results are right and individual differences in biology account for some SSI risk, then insurance penalties imposed on hospitals that fail to prevent SSIs may be at least partly misguided. It’s clear, he says, that at least a portion of these infections may occur regardless of adherence to infection-control standards, including those recommended by the Centers for Disease Control and Prevention. The problem, Faraday says, with Medicare imposing financial penalties on hospitals with higher SSI rates that 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.” “There’s no doubt we can and should do better,” he says, “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 research was supported in part by the National Institutes of Health’s National Center for Research Resources and National Center for Advancing Translational Sciences.