Implants

Antibiotic Prophylaxis for Selected Implants and Devices

Karen A. Baker, RPh, MS

Copyright 2000 Journal of the California Dental Association.

Certain implants or devices are widely believed to put patients at risk from oral bacteremia. They include but are not limited to intravascular access devices, solid organ transplants, vascular grafts, coronary artery stents, breast implants, and penile prostheses. The purpose of this article is to review the risk of implant or device infection from transient bacteremia of oral origin and to provide recommendations for appropriate dental management. Since dental treatment bacteremias are a very rare cause of metastatic infections, attributing causality to dental treatment procedures can be viewed as unfounded in almost all cases.

Many types of medically compromised patients may be at risk of distant site infections from transient bacteremia of oral origin. The most widely recognized type of patients are those with cardiac abnormalities who are thought to be at increased risk of infective endocarditis.¹ The significance of dental procedures as a cause of infective endocarditis and the use of antibiotic prophylaxis to prevent it have become increasingly controversial issues.^2-4 Nevertheless, eight versions of American Heart Association guidelines regarding use of antibiotic prophylaxis to prevent infective endocarditis have been published since 1955, and most dental professionals regard them as a standard of care for patients with cardiac abnormalities.⁵

The most frequently encountered types of patients potentially at risk from transient oral bacteremia are those with total joint replacements.⁶ There is no data to support any relationship between bacteremias from dental treatment and prosthetic joint infections.⁷ However, a number of authors have recommended antibiotic prophylaxis for a small percentage of prosthetic joint patients thought to be at increased risk of late infection. Norden⁸ concluded that antibiotic prophylaxis seemed advisable for patients with periodontitis or other dental infections. Thyne and Ferguson⁹ proposed that prophylaxis was justifiable for patients who were immunosuppressed by virtue of chronic drug therapy or disease. Deacon and colleagues¹⁰ concluded that antibiotic prophylaxis was also appropriate for patients with risk factors for late infections in total joint replacements. A retrospective study of 3,490 patient records by Waldman and colleagues¹¹ gave further support for the previously cited recommendations. An advisory statement issued by both the American Dental Association and the American Academy of Orthopaedic Surgeons¹² has brought welcome clarity to this contentious issue. The panel stated that antibiotic prophylaxis is not routinely indicated for most dental patients with prosthetic joints. Dentists are asked to consider a small number of conditions as potential risk factors for late infections. These conditions include immunosuppression by virtue of drug or disease, insulin-dependent diabetes, malnourishment, hemophilia, and a number of joint-related complications including infection and revision. In addition, the first two years after joint replacement surgery is considered a higher risk period for infection.

Many physicians continue to make recommendations that conflict with this advisory statement, so dentists should seek consultation to clarify patient-specific modifiers. If the physician insists upon the use of antibiotic prophylaxis even in the absence of known risk factors, then the physician should write the prescription for antibiotics. Whether physicians who insist upon antibiotic prophylaxis are unfamiliar with the advisory statement or are simply choosing to disagree with the published conclusions is unclear.

There are a growing number of medical conditions for which infection from oral pathogens is a concern. Conditions where oral pathogens have reportedly caused infection by the hematogenous route include immunosuppression from cancer therapy,^13-16 hepatic abscess,¹⁷ brain abscess,^18,19 meningitis,²⁰ and paraspinal abscess.²¹

Certain implants or devices are widely believed to put patients at risk from oral bacteremia. They include but are not limited to intravascular access devices, solid organ transplants, vascular grafts, coronary artery stents, breast implants, and penile prostheses. The purpose of this article is to review the risk of implant or device infection from transient bacteremia of oral origin and to provide recommendations for appropriate dental management. There are no national or international guidelines nor prospective risk-benefit studies in humans for any of these potential uses of antibiotic prophylaxis. Accordingly, physician recommendations are locally formulated and vary greatly from one part of the country to another. When antibiotic prophylaxis is recommended, the current AHA regimens should be prescribed. However, the use of current AHA regimens for antibiotic prophylaxis not intended to prevent bacterial endocarditis is not approved by the AHA. Issues such as principles of antibiotic prophylaxis²² and the role dental procedures play in determining the incidence, nature, and magnitude of bacteremia²³ have been extensively reviewed elsewhere and are beyond the scope of this article. Throughout this discussion, the dentist must bear in mind that dental treatment bacteremias are a very rare cause of metastatic infections.⁷ To further complicate matters, the odds of a bacteremia emanating from the mouth due to daily patient procedures (eating, brushing, and flossing) are 1,000 to 8,000 times more likely than from dental treatment procedures.⁷ Therefore, attributing causality to dental treatment procedures can be viewed as unfounded in almost all cases.

Hemodialysis Arteriovenous Shunts

There are approximately 268,000 patients with end stage renal disease undergoing dialysis (either peritoneal or hemodialysis) this year in the United States.²⁴ Most of these patients undergo hemodialysis, which requires a vascular access capable of delivering high blood flow. The majority of hemodialysis patients have either a native vein or synthetic graft arteriovenous shunt constructed to provide access to high blood flow. Native vein shunts or fistulas typically involve connection of the radial artery to the cephalic vein and are used in 29 percent of hemodialysis patients.^25,26 Artificially constructed arteriovenous shunts or grafts (bovine or synthetic polytetrafluoroethylene) are usually constructed in the forearm using the brachial artery and cephalic vein and are used in 64 percent of hemodialysis patients.²⁶ For the 7 percent of patients without suitable arteriovenous access, central venous catheters such as internal jugular vein cuffed and tunneled catheters are used for hemodialysis access.

Infection is the principle cause of morbidity and the second leading cause of death in patients undergoing hemodialysis for end-stage renal disease.^27,28 Bloodstream infections are the major infectious complication and result from repetitive access to the vascular system.²⁹ Native vein fistulas result in the lowest rate of bacteremia followed by artificial arteriovenous grafts.³⁰ The highest rates of bacteremia are consistently found in hemodialysis patients with central venous catheters.²⁹ The concern about transient oral bacteremia is related to the potential for increased risk of two distinct endovascular infections in hemodialysis patients. These infections are infective endocarditis and vascular access device infection.

Vascular access device infections appear to be primarily related to penetration of the device through overlying skin, which results in contamination with staphylococci and streptococci as well as other skin bacteria.^31,32 Bacteremia appears to be an uncommon cause of vascular access device infections³³ but newly placed grafts are at higher risk than established grafts.³⁴ Ideally, no elective invasive dental procedures should be performed within six weeks of either new graft placement or surgical revision of an established graft.

Hemodialysis patients appear to be at increased risk of infective endocarditis,^35-37 but the causative factors and sequence of events leading to it are unclear. What is clear is that most clinicians that advocate antibiotic prophylaxis prior to bacteremic dental procedures are primarily concerned with preventing infective endocarditis.^38,39 There have been cases of it in which dental procedures were recently performed and oral organisms were isolated,⁴⁰ but evidence of a consistent causal relationship is tenuous at best. A few references continue to suggest that the primary purpose of antibiotic prophylaxis is to prevent vascular access device infections^41,42 but this position is not even as defensible as prophylaxis to prevent infective endocarditis.

Despite the lack of data to support antibiotic prophylaxis for hemodialysis patients,²² a number of frequently cited authors have recommended this practice until the risk vs. benefit can be more confidently defined.^38,39,43 The dentist should consult the patient’s nephrology clinic prior to treatment and should advise the hemodialysis patient that excellent ongoing oral hygiene is probably more important than acute antibiotic coverage in preventing hemodialysis-related infections.^44,45

Solid-Organ Transplants

Renal transplant patients are the most common type of solid-organ transplant patients encountered in the dental office, with 285,900 transplants performed in 1994 and a five-year survival rate of 80 percent. Next in frequency are liver transplant patients with 34,225 performed in 1994 and a five-year survival rate of 70 percent. There were 29,900 heart transplants performed in 1994 with a 70 percent survival rate after five years.⁴⁶ A primary goal in organ transplant patients is to prevent or effectively treat infection, which is the most common life-threatening complication of long-term immunosuppressive therapy. A recent review delineated the principles guiding infectious-disease practice in transplantation, emphasizing the prevention and early recognition of infection and the avoidance of drug-related toxic effects.⁴⁷

Since the immunosuppressive regimens used in all forms of solid-organ transplantation are similar (cyclosporine or tacrolimus), there is a consistent timetable for the occurrence of different infections. Therefore, kidney, liver, and heart transplants will be discussed as a group. However, heart transplant patients are at increased risk of developing cardiac valve abnormalities, which could predispose them to endocarditis. The dentist must continually consult with the patient’s physician to determine whether antibiotic prophylaxis to prevent endocarditis is deemed necessary.²² Assuming that elective dental treatment is inadvisable until at least six months or greater after transplantation, only that period will be considered in the following discussion of dental management.

In terms of their infectious disease problems, patients can be divided into three groups. The majority of patients (80 percent) will have a good result with infectious disease problems similar to those of other community members. About 10 percent of patients will have chronic or progressive viral infections (hepatitis B or C, cytomegalovirus, Epstein-Barr virus, papillomavirus), which may cause injury to organs or contribute to cancer.⁴⁷ In 5-10 percent of transplant recipients, recurrent or chronic rejection develops, which necessitates increased immunosuppressive dosages. These patients are most likely to develop opportunistic infections and require lifelong prophylaxis with trimethoprim-sulfamethoxazole in addition to safeguards against environmental exposure to various pathogens.⁴⁷ The latter two groups of patients would theoretically be at higher risk from transient bacteremias.

Since there is no data demonstrating increased infection risk due to transient oral bacteremias, it seems reasonable to make the antibiotic prophylaxis decision on a case-by-case basis with transplant center consultation. In the past, many centers routinely recommended antibiotic prophylaxis for all transplant patients but increasingly, only those higher risk patients in chronic rejection are considered to be at substantial risk from oral bacteremia.⁴⁶ The

decision to use antibiotic prophylaxis and the selection of a regimen, if indicated, must be made in consultation with the patient’s transplant physician. It is unlikely that patients with stable grafts and good to excellent oral health are at risk from infrequent and brief bacteremias.²² On the other hand, patients in chronic rejection or those with oral infections may best be protected with a short-term antibiotic regimen prior to invasive dental procedures. Immediate and aggressive treatment of acute oral infections along with meticulous maintenance of soft tissue health would appear to be important strategies in minimizing the risk of infection in all transplant patients.³⁹

Vascular Grafts

Many dental patients suffer from one or more cardiovascular conditions that predispose them to vascular damage. Conditions such as hypertension, diabetes, and especially atherosclerosis may lead to peripheral artery occlusion or development of an aneurysm.⁴⁸ Over 90 percent of abdominal aneurysms originate below the renal arteries, while aneurysms of the proximal aorta are much less common.⁴⁸ Prosthetic vascular graft materials such as Dacron and polytetrafluoroethylene are sutured into vascular walls to restore circulation or prevent aneurysm rupture.⁴⁹

The reported incidence of vascular graft infections ranges from less than 1 percent to more than 5 percent and varies with the site of graft placement.⁵⁰ Grafts implanted in the inguinal area have a higher rate of infection than do grafts that lie entirely within the abdomen.⁵⁰ Mechanisms of vascular graft colonization⁵⁰ are listed in Table 1. The predominant organisms found in graft infections are listed in Table 2⁵⁰ and originate primarily from the bowel or skin. Oral organisms only rarely infect aortic aneurysm grafts,⁵¹ but overall mortality rates from such infections range from 25 percent to 88 percent.^49,52,53

The risk of graft infections from transient oral bacteremia is unknown, but any presumed risk diminishes as the graft incorporates into the host tissue.⁵⁰ Pseudointima composed of connective tissue and fibrin begins to form on the inner surface of the graft. True endothelium does form but rarely extends more than 10 mm beyond the anastomosis.^50,52 This process may take three to six months and does not preclude the possibility of late graft infection.⁵⁴ Most authors agree that antibiotic prophylaxis is indicated for new grafts of less than six months^50,54,55 but only Lindemann⁵⁵ recommended antibiotic prophylaxis prior to dental procedures for the life of any synthetic vascular graft. Pallasch²² suggested an intermediate approach of using antibiotic prophylaxis only for patients with major vessel grafts such as those involving the aorta. Physician consultation to confirm the type, location, and size of the graft along with reinforcement of strict oral homecare would seem prudent. A summary of these recommendations is listed in Table 3.

Coronary Artery Stents

Percutaneous transluminal coronary angioplasty is a widely accepted treatment for coronary artery disease with a more than 90 percent success rate.⁵⁶ However, abrupt vessel closure during the procedure and late restenosis limit its effectiveness.⁵⁶ Since 1986, intracoronary stent implantation has been used in conjunction with percutaneous transluminal coronary angioplasty to optimize coronary dilation by compressing the irregular disrupted surface of the atherosclerotic plaque resulting from the intervention.⁵⁸ The luminal diameter is increased by the expanding force of the stent, which acts against the elastic recoil of the vessel and may lead to further improvement in the vessel lumen beyond that obtained at implantation.⁵⁷ However, the presence of a foreign body in the vasculature poses obvious risks including thrombosis or infection. The issue of antithrombotic therapy after intracoronary stenting was recently examined⁵⁸ and will not be discussed here.

Infection of the arterial wall subsequent to coronary artery stent placement is exceedingly rare with only two cases reported.^59,60 The infecting organisms were Staphylococcus aureus⁵⁹ and Pseudomonas aeruginosa, and neither patient survived. Paget and colleagues⁶¹ recently employed a swine model to determine if 1 gram of intravenous cefazolin would prevent stent/artery complex infections if given before a bacterial challenge at the time of stent

placement and four weeks later. The authors also administered the bacterial challenge at three months post stent placement without benefit of antibiotic prophylaxis. In this investigation, S. aureus was the challenge organism because it has been the leading pathogen identified in stent infections at other sites. Antibiotic prophylaxis was definitely protective at the initial placement interval as well as at the 28-day interval. However, the infection rate at the three-month interval was very low. The authors speculated that the mechanism by which stent arteritis occurs and progresses may be based on endothelial denudation from the angioplasty itself. Friction from the expanding metal stent struts could potentially increase this denudation creating an arterial media that could serve as a nidus for bacterial adherence and colonization.⁶¹ Based on the results of their study, Paget and colleagues⁶¹ recommended that antibiotic prophylaxis should be routinely administered prior to arterial stent deployment and also prior to invasive procedures where bacteremia may occur for the first three months following stent placement.

These recommendations seem reasonable and do not require the long-term use of antibiotic prophylaxis in coronary artery stent patients. Previous recommendations for possible antibiotic prophylaxis up to six months after stent placement but none thereafter have been published.¹

Breast Implants

Breast augmentation with saline implants remains a common surgical procedure despite recent controversy surrounding silicone breast implants.^62,63 About 50,000 implants per year are performed for reconstructive needs following cancer treatment, and about 90,000 bilateral breast implants are placed each year for esthetic reasons.⁶ The postoperative infection rate is 1 percent to 4 percent and S. epidermidis and S. aureus are the most common pathogens.⁶⁴ Only one case of late breast implant infection caused by a potentially oral organism has been reported.⁶⁵ The patient was young and in good health and had silicone gel implants three years prior to a series of 14 dental procedures over an eight-month period. During the series of dental procedures, three separate courses of oral antibiotic therapy were prescribed by the dentist. Three days after the final dental appointment for crown placement, the patient noted tenderness and diffuse swelling of the right breast. The diagnosis was breast abscess and the patient was placed on cephalexin. Two days later, the implant was removed and the antibiotic therapy was switched to ciprofloxacin subsequent to drainage of 300 ml of yellow, turbid fluid. The organism cultured from the breast drainage was Clostridium perfringens, which is not a component of normal skin flora but is ubiquitous in the intestinal tract and in soil.⁶⁶ Cultures of the oral cavity and oropharynx performed after at least five days of antibiotic therapy failed to grow Clostridium perfringens. The authors concluded that breast implant patients should receive antibiotic prophylaxis prior to procedures likely to cause bacteremia and further recommended that the regimen should be aimed at eradication of Staphylococcus species.⁶⁵

Bacteremic breast implant infections are truly rare. The fact that only one case of possible oral organism-related breast implant infection has been reported among the hundreds of thousands of breast implant patients lends credence to that assertion. If bacteremia truly put breast implants at risk of infection, then any woman immunosuppressed by virtue of drug therapy or disease would be an easy target for oral organisms. Hundreds of breast cancer survivors with breast reconstruction implants would presumably be at substantial risk, but no case reports confirm this. Despite the apparently negligible risk, some authors continue to recommend antibiotic prophylaxis prior to invasive dental procedures.^64,65 The prudent dentist should always weigh the risk of prophylactic antibiotic therapy against the potential benefit in a particular group of patients. For the hundreds of thousands of women with breast implants, the decision not to prescribe prophylaxis is clearly justified.⁴¹ If the patient’s plastic surgeon is adamant about the necessity of antibiotic prophylaxis, then that physician should write the prescription.

Penile Prostheses

There are two types of penile prostheses currently used for erectile dysfunction. The malleable or semi-rigid devices are either pure silicone rubber or contain an intertwined central spring-loaded core that can be locked for activation and unlocked for the flaccid state.⁶⁷ The inflatable devices are either self-contained cylinders or so-called two-or three-piece devices. No penile prostheses contain silicone gel,⁶⁷ and selection of the appropriate device is based on patient and surgeon preference as well as cost.

Infection is an uncommon but disastrous complication associated with penile prostheses with an incidence ranging from 0.6 percent to 8.9 percent.⁶⁷ Patient factors predisposing them to a higher infection risk include spinal cord injury, poorly controlled diabetes, history of urinary tract infections, and replacement device operation.^67,68 A recent prospective trial has challenged the notion that degree of diabetes control correlates with infection risk.⁶⁹ The authors concluded that neither elevated fasting blood sugar or insulin dependence increased penile prosthesis infection risk.⁶⁹ Most infections occur within three months after implantation, and more than 60 percent of the infections are caused by S. epidermidis.⁷⁰ Identification of the source of S. epidermidis infection is further complicated by the fact that patients may remain asymptomatic and functional for up to five years after initial innoculation.⁷¹

Late infection from hematogenous sources is very rare, with only two such reports in the literature. Carson and Robinson⁷¹ reported three cases of penile prosthesis infection occurring subsequent to either a dental abscess or extensive treatment of dental caries. All three patients were diabetics and the infecting organisms were either staphylococcal or streptococcal. Since these organisms originate from skin as well as the oropharynx, the actual source cannot be identified with confidence. The authors concluded that prophylactic antibiotics administered prior to the dental manipulations could have diminished the threat of prosthesis infection.⁷¹ Kabalin and Kessler⁶⁸ described two cases of penile prosthesis infection in which dental procedures were performed either one or three weeks prior to hospitalization. No organism was identified in either case, yet the authors concluded that all penile prosthesis patients should be premedicated prior to invasive dental procedures.⁶⁸

In a survey of 297 responding urologists in the United States,⁷⁰ 58 percent felt that dental bacteremias posed very slight risk of infecting the healed penile prosthesis. The majority (57 percent) of urologists surveyed did not recommend antibiotic prophylaxis prior to invasive dental procedures. None of the respondents reported experience with penile prosthesis infections related to dental bacteremia.

Despite the fact that dental bacteremias have been implicated but not proven as a source in only five penile prosthesis infection cases, some authors recommend antibiotic prophylaxis prior to dental procedures.^67,68,71,72 Because hematogenous penile prosthesis infections are so rare, it is probably most appropriate not to prescribe antibiotic prophylaxis. If a particular patient is significantly immunocompromised or at higher risk due to chronic infections, antibiotic prophylaxis may be justifiable after consultation with the patient’s primary care physician. Elective dental treatment should be deferred until the penile prosthesis incisions are healed, which may take up to three months.

Conclusion

Dentists and physicians alike are confused and conflicted about antibiotic prophylaxis of patients for whom no published guidelines are available. A close examination of data on all six types of implants or devices reviewed in this article points toward a common scenario. A limited number of case reports that temporally associate dental treatment with implant infection are put forth as evidence of high enough infection risk to justify routine prophylaxis. Bacteriologic confirmation is either debatable or absent, and no prospective trials are available or forthcoming due to risks and liability. Concern with the high morbidity and mortality associated with all six implant and device infections seems to supercede rational consideration of risk vs. benefit. How can dentists make rational clinical judgments about antibiotic prophylaxis given these difficult circumstances? An awareness of published data along with constructive physician consultation based on these data is a prudent way to formulate patient management strategies. Patient education should be aimed at reducing chronic bacteremia by maintaining excellent oral health and immediate reporting of symptoms indicative of acute infections of the head and neck..

Author

Karen A. Baker, RPh, MS, is an associate professor at the University of Iowa Colleges of Dentistry and Pharmacy.

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To request a printed copy of this article, please contact/Karen A. Baker, RPh, MS, South 306 Dental Science Building, University of Iowa College of Dentistry, or at karen-baker@uiowa.edu.