Proper timing essential for prophylactic drugs

Study looks at ways to prevent SSIs

Between 40% and 60% of surgical-site infections can be prevented with the use of prophylactic antibiotics, but overuse, underuse, improper timing, and misuse of antibiotics occur in 25% to 50% of all operations, according to CMRI, a San Francisco-based quality improvement organization working with the Centers for Medicare & Medicaid Services (CMS).

CMS and the Centers for Disease Control and Prevention are conducting a national health care quality improvement project to prevent postoperative infection, says Mary Nash, RN, CNOR, surgical service line director for Promina Gwinnett Hospital System in Lawrenceville, GA, and one of the participants. One of the project’s goals is to improve the selection and timing of antibiotic administration, she says. As part of the study, researchers are looking at the rapidly expanding area of ambulatory surgery.

"Same-day surgery cases that are good candidates for prophylactic antibiotics include tonsillectomy and adenoidectomy, head and neck procedures, urologic, and gynecological procedures," Nash says. Because all of these procedures require the surgeon to work within the abdominal cavity or in proximity to other organs, there is greater risk of exposure from different bacterium than procedures that are considered "clean procedures," she explains.

Knee arthroscopy and many plastic surgery procedures carry a low risk of infection, so antibiotics are not needed, says Dennis G. Maki, MD, professor of medicine in infectious diseases at the University of Wisconsin in Madison. A surgeon only should administer a prophylactic antibiotic for a clean procedure if the patient is diabetic or has any immunosuppressive condition, he adds.

Nash points out that the national study is looking at a one-hour time frame for prophylaxis. "We have decided that in our facility, we [will] administer the antibiotic intravenously 30 minutes prior to the first incision." Timing is critical because you want to make sure the antibiotic is in the tissue when you begin the procedure, she explains.

The major risk for infection in clean same-day surgeries comes from the staphylococci that are found on the skin, Maki says. Cholecystectomy or gynecological patients are at risk for infection from anaerobic bacteria, he points out.

One of the more commonly used prophylactic antibiotics is cefazolin, Nash says. The dosage is 1 g, except when the patient weighs 20 pounds more than the ideal body weight, then 2 g is given; if the procedure lasts longer than four hours, an additional dose is given during surgery, she says.

Cefoxitin is a good choice for gynecological patients because it is effective against anaerobic bacteria, Maki suggests. Postoperative prophylactic antibiotics generally are not needed or recommended, he says. Unnecessary antibiotics can increase incidence of diarrhea or vaginitis, he says.

"Some of our surgeons prescribe oral antibiotics for patients who have their tonsils or adenoids removed, but that is the only time we continue antibiotics with no sign of infection," Nash says. In addition to studying the effect of prophylactic antibiotics on surgical site infection, the 13-month collaborative study looks at other practices as well, she says. "We’ve already realized that the use of clippers rather than razors reduces infection, so clippers are our standard practice in both inpatient and outpatient surgery areas," Nash says. "Surgeons do have to become accustomed to an incision site that isn’t as smooth, but there’s less trauma to the patient’s skin and less risk of infection."

Other items included in the study are the effect of keeping oxygen levels at 80% or above during surgery and keeping patients at normal temperature levels in the post-anesthesia care unit, Nash adds. "We aren’t far enough into the project to have conclusive data that these efforts are reducing our already low surgical site infection rate, but these activities are supported in a variety of literature," she says.

(Editor’s note: For more information about the collaborative study, go to