Despite numerous guidelines, joint interprofessional collaboration, and years of data collection, the use of antibiotic prophylaxis before dental procedures remains controversial. There continues to be disagreement on indications, justification, and outcome of the use of various antibiotic prophylaxis regiments. This is complicated by the lack of data demonstrating any positive or negative impact on the care of patients. The dental community has distanced itself from a leadership role in this conversation, based on multiple concerns including fear of litigation, lack of clear pathophysiology, and unclear cause-effect relationship.
Key points
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There is no evidence to support the routine use of antibiotic prophylaxis before dental procedures to prevent infective endocarditis.
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There is no evidence to support the routine use of antibiotic prophylaxis before dental procedures to prevent prosthetic joint infection.
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There is no evidence to support an association between the bacteremia after dental procedures and incidence of IE or PJI.
Introduction
The theoretic need for the use of antibiotic prophylaxis is summarized in the context of bacteremia, presumably from the oral cavity. Oral organisms entering the bloodstream, via invasive dental procedures, can potentially colonize vulnerable areas, such as defective heart valves, prosthetic joints, and implanted devices, such as cardiac stents or hemodialysis shunts. The colonization of these vulnerable sites can result in various sequlae, such as valvular damage, infective endocarditis (IE), and failure of prosthesis or implanted devices. Despite the theoretic context, there are multitudes of variables that often are not included into the equation. These variables include, but are not limited to, the extent of bacteremia, species of bacteria, host susceptibility, presence of comorbidities, type of implanted devices, type of antibiotics used, bacteria response to the antibiotics, and the nature of dental procedures. Practitioners often balance these variables with the perceived benign nature of antibiotics, and elect to use antibiotics rather than considering the risks and benefits of not using them. This is further complicated by an unrealistic fear of legal reprisal and whether a practitioner can justify their decision to an unrelenting legal team.
Introduction
The theoretic need for the use of antibiotic prophylaxis is summarized in the context of bacteremia, presumably from the oral cavity. Oral organisms entering the bloodstream, via invasive dental procedures, can potentially colonize vulnerable areas, such as defective heart valves, prosthetic joints, and implanted devices, such as cardiac stents or hemodialysis shunts. The colonization of these vulnerable sites can result in various sequlae, such as valvular damage, infective endocarditis (IE), and failure of prosthesis or implanted devices. Despite the theoretic context, there are multitudes of variables that often are not included into the equation. These variables include, but are not limited to, the extent of bacteremia, species of bacteria, host susceptibility, presence of comorbidities, type of implanted devices, type of antibiotics used, bacteria response to the antibiotics, and the nature of dental procedures. Practitioners often balance these variables with the perceived benign nature of antibiotics, and elect to use antibiotics rather than considering the risks and benefits of not using them. This is further complicated by an unrealistic fear of legal reprisal and whether a practitioner can justify their decision to an unrelenting legal team.
History of antibiotic prophylaxis guidelines for infective endocarditis
In 1955, the American Heart Associations (AHA) published its first recommendations for prevention of infective endocarditis. These guidelines have evolved over the past decades by work of the AHA and American College of Cardiology Task Force groups. International societies have also published their own recommendations and guidelines, further contributing to the evolution of most recent guidelines.
The updates in the available guidelines, from 1955 through 2007, have taken several factors into consideration. Such factors as drug resistance bacteria, risk stratification of the patient population, etiology of bacteremia, and the complexity of the prophylaxis regiment have been included in development of these guidelines. The 1997 guidelines were the first to acknowledge that IE is often not associated with invasive procedures, and more frequently caused by random bacteremia from routine activities. The rational for these guidelines was largely based on expert opinion and what seemed prudent practice to prevent a life-threatening infection. The evidence used to develop these guidelines could be scored as class IIB, and level of evidence C.
In 2007, the most recent guidelines were developed based on the publications and data questioning the efficacy of antibiotics therapy in prevention of IE, and in an attempt to reduce the complexity of the previous guidelines. These new guidelines have significantly reduced the use of antibiotic prophylaxis to prevent IE.
Justification for Antibiotic Prophylaxis in Prevention of Infective Endocarditis
Despite advances in diagnosis and treatment of IE, it continues to be a dangerous disease. Morbidity and mortality are 50% in high-risk patients, such as those with prosthetic valves, congenital heart disease, and previous history of IE.
Development of IE is the net result of a complex set of circumstances involving bloodstream pathogens interacting with the tissue matrix and platelets at the site of endothelial cell damage. This process is summarized in the stages noted next. It is also important to note that the clinical manifestations of IE are further affected by the host immune system.
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Formation of nonbacterial thrombotic endocarditis (NBTE): Some cardiac anomalies, congenital or acquired, can result in turbulent blood flow, which can cause endothelial injury. Adhesion of platelets and fibrin to the site of trauma can potentially lead into NBTE.
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Transient bacteremia: Trauma to oral mucosal surfaces can result in transient bacteremia from the site of injury, populating the bloodstream with viridans group streptococci and other common oral microflora
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Bacterial adhesion: The bacteria within the bloodstream can adhere to the site of endothelial injury and NBTE. Some microorganisms, such as viridans group streptococci, have surface components that allow their adhesions to various surfaces. This surface characteristic can serve as a virulence factor in development of IE. The adhesion of other organisms, such as staphylococci, is facilitated either by surface components or formation of a biofilm, particularly on the surface of implanted devices. There has been some work on vaccines directed to the adhesion characteristics of viridian group streptococci and staphylococci resulting in some protection against IE in experimental models.
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Proliferation of bacteria: On adherence to NBTE, microorganisms rapidly proliferate forming bacterial vegetation within the damaged endothelial surface. These isolated foci can be potentially unaffected by the host immune system, allowing their further growth and invasion. More than 90% of these vegetations are metabolically inactive rendering them less responsive to antibiotics. The bacterial vegetation within the injured endothelial surfaces can ultimately result in further damage to the cardiac tissue and development of IE.
Gene sequencing, such as 16S rRNA, has identified more than 6 billion bacteria representing more than 700 species. These bacteria and their colonies commonly exist in the form of biofilm in oral environment, including but not limited to soft tissue, teeth, and prostheses. A unique feature of oral bacterial and plaque biofilm is their close proximity to the highly vascularized tissue bed, particularly in the periodontal pockets.
These organisms can gain access into the bloodstream via multitude of mechanisms and portals. Perhaps the most obvious and common route is via trauma-induced procedures, such as periodontal probing, dental extractions, scaling, and other instrumentation resulting in exposure of vascular bed to spillage of bacteria from the plaque biofilm. Although this trauma is often attributed to invasive dental procedures, other activities, such as chewing, brushing, and flossing, fall under this category and induce bacteremia.
For example, it has been shown that 20% of patients demonstrated bacteremia after chewing. Bacteremia has been detected in 75% of patients with periodontitis and 20% of patient experiencing gingivitis. In one study, bacteremia was noted after tooth brushing in 23% of patients compared with 60% after single tooth extraction. However, the authors suggested that the frequency of tooth brushing may potentially expose patients to a higher cumulative risk from bacteremia compared with single tooth extraction.
In summary, bacteremia can be quantified based on two general parameters. First is the degree of inflammation present at the site, which demonstrates the type and microbial load of the biofilm. Second is the extent of trauma or tissue damage that has occurred exposing the bloodstream to the biofilm.
The guidelines recommending antibiotic prophylaxis for prevention of IE are primarily based on three main observations: (1) bacteremia has been recognized as a cause of IE, (2) viridans group streptococci can result in a critical bacteremia, and (3) these organisms are susceptible to common antibiotics.
The role of dental procedures as a source of bacteremia and the efficacy of antibiotics to prevent IE from such bacteremia continues to be nebulous. Several case-controlled studies have questioned the proposed relationship between invasive dental procedures and IE. A study of 275 patients in the Netherlands demonstrated that IE was caused by random bacteremia rather than invasive dental procedures. Studies in France and the United States demonstrated no correlation between dental treatment and IE compared with control subjects.
However, these studies have not addressed the ineffectiveness of antibiotics use in prevention of IE. The incidence of IE from dental procedure without the use of antibiotics has been estimated at 1 in 46,000. In comparison, the incidence of IE in patients with antibiotic use before dental procedures is estimated at 1 in 150,000. The authors of this study have therefore concluded that a huge number of prophylaxis doses of antibiotics would be needed to prevent a very small number of potential IE cases. In light of this high number needed to treat, there is a greater concern for the adverse effects and complications associated with the antibiotics use.
Generally speaking, the risk of adverse effects from a single dose of antibiotics is minor. Risk of fatal anaphylaxis reaction has been reported at 15 to 25 people per million. Antibiotic resistance is less likely to occur for a single dose of antibiotics. However, with continued use, resistance becomes a more concerning factor. Spillage of antibiotics and other pharmaceuticals in the drinking water has captured the attention of the world community and resulted in several health-related concerns.
Patient evaluation and management
Limitations of the available evidence and continuous changes in the clinical profile of IE have led to revision of antibiotic prophylaxis guidelines by various organizations worldwide. In general, all these guidelines aim to reduce the ambiguity, complexity, and requirements for antibiotic prophylaxis use toward prevention of IE. In the United States, the AHA established the most recent guidelines in 2007 gaining endorsement from the American Dental Association (ADA). These guidelines recommend antibiotic prophylaxis use only for patients with highest risk of developing IE. Such guidelines have been received with mixed reactions, and some cardiologists consider them quite alarming and a deviation from the previously accepted clinical practices. Dental providers equally have been confused by the new guidelines, and unable to navigate between the AHA recommendations and medical providers discomfort with changing their established practice.
These debates behoove dental providers to take a more active role in the decision-making process for the use of antibiotic prophylaxis. In general, patients in good health, with healthy dentition and peridontium should not be prescribed antibiotics prophylaxis for prevention of IE, unless they meet the specific criteria for the highest risk groups outlined by the AHA guidelines. The review of various guidelines and their revisions point out to three general domains for consideration: (1) the patient’s medical risk factors and state of oral health, (2) invasiveness of the dental procedures, and (3) stratification of the risks for IE.
The relevance of the patient’s medical risk factors and state of oral health has been well supported by the literature (all articles). Patients with compromised immune system, such as those with uncontrolled diabetes or recent history of chemotherapy, may be at great risk for adverse event from bacteremia regardless of their compliance with the AHA antibiotic prophylaxis guidelines. If invasive dental treatment is indicated, the dental provider should consider the use of antibiotics before such procedures even though patients may not be considered high risk for IE. Defining the immune competence of patients and determining their potential risk for postprocedure adverse events is an important step in evaluation and caring for all patients. In the context of IE, it becomes an important factor in determining the justification for use of antibiotic prophylaxis.
Another common denominator in the discussion surrounding IE has been the patient’s overall oral health status. Characteristics of oral biofilm, presence of advance periodontal disease, the extent of dental carries, and homecare habits have been the centerpiece for concerns associated with bacteremia from oral origin. Identification of viridian group streptococci and Staphylococcus spp in patients with IE, in absence of dental procedures, has been linked to the occurrence of random bacteremia.
Although the maintenance of oral health should be a routine aspect of a dental practice, clinical outcomes are not always favorable. Dental providers should consider identifying patients with higher risk of IE and consider implementation of more rigorous oral hygiene care plan. Even patients with moderate risk for IE may benefit from antibiotic prophylaxis in preparation for provision of invasive dental procedures in highly inflamed areas or sites with extensive presence of biofilm.
Compared with cardiologists or other medical providers, dental providers can most appropriately estimate the invasiveness of the planned procedure, extent of local inflammation, and potential for bacteremia secondary to their treatment. Based on this information, dental providers can more objectively support the value of antibiotic prophylaxis for prevention of IE, given the patient’s risk factor. Similarly, despite empiric recommendations, dental providers should resist the unnecessary use of antibiotic prophylaxis when not justified by the invasiveness of the procedure and health of local soft tissue.
The risk assessment for IE at times requires a collaboration with the patient’s health care team. There is no evidence to support the benefit of antibiotics prophylaxis in patients with low or moderate risk for IE. Therefore, in absence of any other relevant health history or clinical findings patients in these categories do not require antibiotic prophylaxis. The dental providers should evaluate medical consultations or other recommendations by medical providers very critically. In absence of the four high-risk categories defined by the AHA, any medical opinion recommending antibiotic prophylaxis should contain supporting information to support deviation from the proposed guidelines.
From the quality of care perspective, exposure of patients to unnecessary antibiotics, regardless of the safety margin, is inappropriate. From the medical-legal perspective, medical consultations or recommendations are simply one health care provider’s opinion. The dental provider is withheld to the standard of analyzing those opinions and formulating a logical decision based on the established treatment guidelines. In such circumstances, and in the event of an adverse antibiotic-related incident, the dental provider may be placed in a position to defend the unnecessary use of antibiotic prophylaxis. This defense may be challenging given guidelines set forth by the AHA, ADA, and other organizations.
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