You are asked to admit two patients. The first is a 75-year-old male with a prosthetic aortic valve on warfarin who presents with bright red blood per rectum and is scheduled for colonoscopy. The second patient is a 35-year-old female with biliary obstruction due to choledocholithiasis; she is afebrile with normal vital signs and no leukocytosis. She underwent endoscopic retrograde cholangiopancreatography (ERCP), which did not resolve her biliary obstruction. Should you prescribe prophylactic antibiotics for either patient?
Providers are often confused regarding which patients undergoing gastrointestinal (GI) endoscopic procedures should receive antibiotic prophylaxis. To answer this question, it is important to understand the goal of prophylactic antibiotics. Are we trying to prevent infective endocarditis or a localized infection?
There are few large, prospective, randomized controlled trials that have examined the need for antibiotic prophylaxis with GI endoscopic procedures. Guidelines from professional societies are mainly based on expert opinion, evidence from retrospective case studies, and meta-analysis reviews.
Review of the Data
Infective endocarditis resulting from GI endoscopy has been a concern of physicians for decades. The American Heart Association (AHA) first published its recommendations for antibiotic prophylaxis of GI tract procedures in 1965. The most recent antibacterial prophylaxis guidelines, published in 2007, have simplified recommendations and greatly scaled back the indications for antibiotics. The new guidelines conclude that frequent bacteremia from daily activities is more likely to precipitate endocarditis than a single dental, GI, or genitourinary tract procedure.1
The American Society for Gastrointestinal Endoscopy (ASGE) reports that 14.2 million colonoscopies, 2.8 million flexible sigmoidoscopies, and nearly as many upper endoscopies are performed in the U.S. each year, but only 15 cases of endocarditis have been reported with a temporal association to a procedure.2
The British Society of Gastroenterology (BSG) found, after reviewing the histories of patients with infective endocarditis from 1983 through 2006, that there is not enough evidence to warrant antibiotic prophylaxis prior to endoscopy. They noted less than one case of endocarditis after GI endoscopy per year as well as significant variation in the time interval between the procedure and symptoms. The BSG also recognized that antibiotic prophylaxis does not always protect against infection and that clinical factors unrelated to the endoscopy may play a significant role in the development of endocarditis.3
Upper GI Endoscopy, Colonoscopy with Biopsy, and Esophageal Dilatation. Administering antibiotics to prevent infective endocarditis is not recommended for patients undergoing routine procedures such as endoscopy with biopsy and colonoscopy with polypectomy. Likewise, patients with a history of prosthetic heart valves, valve repair with prosthetic material, endocarditis, congenital heart disease, or cardiac transplant with valvulopathy do not need prophylactic antibiotics before GI endoscopic procedures. However, for patients who are being treated for an active GI infection, antibiotic coverage for enterococcus may be warranted given the increased risk of developing endocarditis. The AHA acknowledges there are no published studies to support the efficacy of antibiotics to prevent enterococcal endocarditis in patients in this clinical setting.1
Unlike routine endoscopy, esophageal dilation is associated with an increased rate of bacteremia (12%-100%).4 Streptococcus viridans has been found in blood cultures up to 79% of the time after esophageal dilation.5 Patients with malignant strictures have higher rates of bacteremia than those with benign strictures (52.9% versus 15.7%). Patients treated with multiple passes with the esophageal dilator compared to those treated with a single dilation have a higher risk of bacteremia.6 All patients undergoing esophageal stricture dilation should receive pre-procedural prophylactic antibiotics.7