Prophylaxis and prevention of infective endocarditis

Infective endocarditis (IE) is a rare disease but with devastating consequences. In-hospital mortality rates of left-sided endocarditis are around 20%, and 5-year mortality rates are up to 40% despite the advances in diagnosis and treatment [ ]. High mortality and morbidity and difficulty in treatment mandate institution of effective preventive measures to lower the incidence of this life-threatening condition. Unfortunately, the low incidence of the disease makes it very hard to obtain high-quality prospective randomized trial data measuring the effects of preventive interventions.

Antibiotic prophylaxis for dental procedures was first recommended by the American Heart Association (AHA) more than 60 years ago [ ]. During the 50 years following the first recommendations, antibiotic prophylaxis was administered to patients with various underlying cardiac conditions undergoing different invasive procedures. Patients and procedures were stratified into high- and low-risk groups in 1977 [ ], and high-, moderate-, and low-risk categories were defined in 1997 guidelines. The latter recommended prophylaxis to the moderate- and high-risk patients undergoing various procedures, including dental procedures [ ]. However, these recommendations were based on animal studies or studies where bacteremia was regarded as a surrogate for endocarditis. In the years to follow, studies showing that patients are experiencing recurrent bacteremia due to daily oral hygiene activities such as brushing, flossing, and even chewing have been published [ ]. Bacteremia with IE causing microorganisms after toothbrushing was especially pronounced in those with poor oral hygiene [ ]. These led to the development of the concept that daily oral hygiene activities might be riskier than sporadic invasive dental procedures in patients with poor oral hygiene. The absence of high-quality data on the effectiveness of antibiotics in preventing IE as well as the potential risks related to antibiotic use have led to a shift in major society guidelines after the mid-2000s. However, the guidelines around the world are still not in complete agreement on whom to administer prophylactic antibiotics as well as which procedures require prophylaxis. European Society of Cardiology (ESC) [ ] and the AHA [ ] guidelines have restricted prophylactic antibiotics to the patients with the highest risk of adverse outcomes. National Institute for Health and Clinical Excellence (NICE) guidelines advised against prophylactic antibiotics completely [ ]. Time trend analysis of IE cases in the United Kingdom has shown that prescriptions of antibiotics for prophylaxis have decreased, and cases of IE have increased in the United Kingdom after the institution of these guidelines [ ]. In 2016 NICE amended the previous recommendations stating that ‘antibiotic prophylaxis is not recommended’ to “not ‘routinely’ recommended” for people undergoing dental procedures, which provided some flexibility to health-care providers in administering antibiotic prophylaxis in selected cases if they felt the patient is at high risk for adverse outcomes [ ]. On the other hand, Japanese Circulation Society guidelines still recommend antibiotic prophylaxis for both high-risk and moderate-risk patients [ ].

Meanwhile, the epidemiology of IE has been changing. More cases are seen in the older adults related to health care and intravenous drug users, leading to a shift in causative microorganisms from streptococci to staphylococci [ , ].