Fight infection before it develops

Proper timing essential for prophylactic antibiotics

Antibiotics can be given prior to surgery to prevent infections, but how effective are they, and are they necessary for all same-day surgery procedures? 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 for the Centers for Medicare & Medicaid Services (CMS).

CMS and the Atlanta-based Centers for Disease Control and Prevention (CDC) are conducting a national health care quality improvement project to prevent postoperative infection, says Mary Nash, RN, BS, 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. (For more information about the collaborative study, go to

"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 should administer a prophylactic antibiotic for a clean procedure if the patient is diabetic or has any immunosuppressive condition, he adds.

Although Maki says the antibiotic can be given within two hours of surgery, Nash points out that the national study is looking at a one-hour timeframe. "We have decided that in our facility, we administer the antibiotic intravenously 30 minutes prior to the first incision," she says. Timing is critical because you want to make sure the antibiotic is in the tissue when you begin the procedure, she explains.

There is more than one type of bacteria that can cause surgical-site infection, Maki says. The major risk for infection in clean same-day surgeries comes from the staphoccoci that are found on the skin, he says. Cholecystectomy or gynecological patients are at risk for infection from anaerobic bacteria, he points out. For this reason, you should choose antibiotics carefully, he adds. (For more information on antibiotics, see "Sources" at the end of this article.)

The most common antibiotic is cefazolin, Nash says. The dosage is 1 g, except when the patient is 20 pounds over the ideal body weight, then 2 g is given, she says. If the procedure lasts longer than four hours, an additional dose is given during surgery, she adds.

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," she 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," she adds.

Other items included in the study are the effect of keeping oxygen levels at 80% or above during surgery and keeping patients at normal thermic levels of 96.8 degrees 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. Anecdotal evidence indicates that all of these efforts do reduce the risk of infection, she adds.


For more information on the prophylactic use of antibiotics, contact:

Mary Nash, RN, BS, CNOR, Surgical Service Line Director, Promina Gwinnett Hospital System, 1000 Medical Center Blvd., Lawrenceville, GA 30045. Telephone: (678) 442-4179. E-mail:

Dennis G. Maki, MD, Professor of Medicine, Section of Infectious Disease, University of Wisconsin Hospital, 600 Highland Ave., Madison, WI 53792. Telephone: (608) 263-6400. E-mail:

For information on antibiotics and their recommended use, contact:

Johns Hopkins Division of Infectious Diseases Antibiotic Guide, This free on-line service is a decision-support tool that provides clinicians with concise, digested, timely information about the diagnosis and treatment of infectious diseases. Visitors can review recommend uses and treatment of infections by specific antibiotics, pathogens, or diagnosis through the site search engine.