Principles of Management and Prevention of Odontogenic Infections

Complete History

The history of the patient’s infection follows the same general guidelines as any history. The initial purpose is to find out the patient’s chief complaint. Typical chief complaints of patients with infections are “I have a toothache,” “My jaw is swollen,” or “I have a gum boil in my mouth.” The complaint should be recorded in the patient’s own words.

The next step in taking of the history is determining how long the infection has been present. First, the dentist should inquire as to time of onset of the infection. How long ago did the patient first have symptoms of pain, swelling, or drainage, which indicated the beginning of the infection? The course of the infection is then discussed. Have the symptoms of the infection been constant, have they waxed and waned, or has the patient steadily grown worse since the symptoms were first noted? Finally, the practitioner should determine the rapidity of progress of the infection. Has the infection process progressed rapidly over a few hours, or has it gradually increased in severity over several days to a week?

The next step is eliciting the patient’s symptoms. Infections are actually a severe inflammatory response, and the cardinal signs of inflammation are clinically easy to discern. These signs and symptoms are the Latin terms dolor (pain), tumor (swelling), calor (warmth), rubor (erythema, redness), and functio laesa (loss of function).

The most common complaint is pain. The patient should be asked where the pain actually started and how the pain has spread since it was first noted. The second sign is tumor (swelling). Swelling is a physical finding that is sometimes subtle and not obvious to the practitioner, although it is obvious to the patient. It is important that the dentist ask the patient to describe any area of swelling. The third characteristic of infection is calor (warmth). The patient should be asked whether the area has felt warm to the touch. Redness of the overlying area is the next characteristic to be evaluated. The patient should be asked if there has been or currently is any change in color, especially redness, over the area of the infection. Functio laesa should then be checked. When inquiring about this characteristic, the dentist should ask about trismus (difficulty in opening the mouth widely) and difficulty in chewing, swallowing (dysphagia), or breathing (dyspnea).

Finally, the dentist should ask how the patient feels in general. Patients who feel fatigued, feverish, weak, and sick are said to have malaise. Malaise usually indicates a generalized reaction to a moderate to severe infection (Fig. 15-6).

In the next step the dentist inquires about treatment. The dentist should ask about previous professional treatment and self-treatment. Many patients doctor themselves with leftover antibiotics, hot soaks, and a variety of other home or herbal remedies. Occasionally, a dentist sees a patient who received treatment in an emergency room 2 or 3 days earlier and was referred to a dentist by the emergency room physician. The patient may have neglected to follow that advice until the infection became severe. Sometimes, the patient did not take the prescribed antibiotic because he or she could not afford to purchase it.

The patient’s complete medical history should be obtained in the usual manner by interview or by self-administered questionnaire with verbal follow-up of any positive findings.

Physical Examination

The first step in the physical examination is to obtain the patient’s vital signs, including temperature, blood pressure, pulse rate, and respiratory rate. The need for evaluation of temperature is obvious. Patients who have systemic involvement of infection have elevated temperatures. Patients with severe infections have temperatures elevated to 101° F or higher (greater than 38.3° C).

The patient’s pulse rate increases as the patient’s temperature increases. Pulse rates of up to 100 beats/min are not uncommon in patients with infections. If pulse rates increase to greater than 100 beats/min, the patient may have a severe infection and should be treated more aggressively.

The vital sign that varies the least with infection is the patient’s blood pressure. Only if the patient has significant pain and anxiety will there be an elevation in systolic blood pressure. However, severe septic shock results in hypotension.

Finally, the patient’s respiratory rate should be closely observed. One of the major considerations in odontogenic infections is the potential for partial or complete upper airway obstruction as a result of extension of the infection into the deep fascial spaces of the neck. As respirations are monitored, the dentist should carefully check to ensure that the upper airway is clear and that breathing is without difficulty. The normal respiratory rate is 14 to 16 breaths per minute. Patients with mild to moderate infections may have elevated respiratory rates greater than 18 breaths/min.

Patients who have normal vital signs with only a mild temperature elevation usually have a mild infection that can be readily treated. Patients who have abnormal vital signs with elevation of temperature, pulse rate, and respiratory rate are more likely to have serious infection and require more intensive therapy and evaluation by an oral and maxillofacial surgeon.

Once vital signs have been taken, attention should be turned to physical examination of the patient. The initial portion of the physical examination should be inspection of the patient’s general appearance. Patients who have more than a minor, localized infection have an appearance of fatigue, feverishness, and malaise. This is a “toxic appearance” (Fig. 15-6).

The patient’s head and neck should be carefully examined for the cardinal signs of infection, and the patient should be inspected for any evidence of swelling and overlying erythema. The patient should be asked to open the mouth widely, swallow, and take deep breaths so that the dentist can check for trismus, dysphagia, or dyspnea. These are ominous signs of a severe infection, and the patient should be referred immediately to an oral and maxillofacial surgeon or emergency room. A recent study of severe odontogenic infections requiring hospitalization found trismus (maximum interincisal opening less than 20 mm) in 73% of cases, dysphagia in 78%, and dyspnea in 14%.

Areas of swelling must be examined by palpation. The dentist should gently touch the area of swelling to check for tenderness, amount of local warmth or heat, and the consistency of the swelling. The consistency of the swelling may vary from very soft and almost normal through a firmer, fleshy swelling (described as having a doughy feeling) to an even firmer or hard swelling (described as feeling indurated). An indurated swelling has similar firmness to a tightened muscle. Another characteristic consistency is fluctuant. Fluctuance is the feeling of a fluid-filled balloon. Fluctuant swelling almost always indicates an accumulation of pus in the center of an indurated area.

The dentist then performs an intraoral examination to try to find the specific cause of the infection. There may be severely carious teeth, an obvious periodontal abscess, severe periodontal disease, combinations of caries and periodontal disease, or an infected fracture of a tooth or the entire jaw. The dentist should look and feel for areas of gingival swelling and fluctuance and for localized vestibular swellings or draining sinus tracts.

The next step is to perform a radiographic examination. This usually consists of the indicated periapical radiographs. Occasionally, however, extraoral radiographs, such as a panoramic radiograph, may be necessary because of limited mouth opening or other extenuating circumstances.

After the physical examination, the practitioner should begin to have a sense of the stage of the presenting infection. Very soft, mildly tender, edematous swellings indicate the inoculation stage, whereas an indurated swelling indicates the cellulitis stage (Fig. 15-7), and central fluctuance indicates an abscess (Fig. 15-8). Soft tissue infections in the inoculation stage may be cured by removal of the odontogenic cause with or without supportive antibiotics, and infections in the cellulitis or abscess stages require removal of the dental cause of infection plus incision and drainage and antibiotics.

Distinctions between the inoculation, cellulitis, and abscess stages are typically in duration, pain, size, peripheral definition, and consistency on palpation, presence of purulence, infecting bacteria, and potential danger (Table 15-3). The duration of cellulitis is usually thought to be acute and is the most severe presentation of the infection. An abscess, however, is a sign of increasing host resistance to the infection. Cellulitis is usually described as more painful than an abscess, which may be the result of its acute onset and distention of tissues.

Edema, the hallmark of the inoculation stage, is typically diffuse and jellylike, with minimal tenderness to palpation. The size of a cellulitis is typically larger and more widespread than that of an abscess or edema. The periphery of a cellulitis is usually indistinct, with a diffuse border that makes it difficult to determine where the swelling begins or ends. The abscess usually has distinct and well-defined borders. Consistency to palpation is one of the primary distinctions among the stages of infection. When palpated, edema can be very soft or doughy; a severe cellulitis is almost always described as indurated or even as being “boardlike.” The severity of the cellulitis increases as its firmness to palpation increases. On palpation, an abscess feels fluctuant because it is a pus-filled cavity in the tissue. Thus an infection may appear innocuous in its early stages and extremely dangerous in its more advanced, indurated, rapidly spreading stages. A localized abscess is typically less dangerous, because it is more chronic and less aggressive.

The presence of pus usually indicates that the body has locally walled off the infection and that the local host resistance mechanisms are bringing the infection under control. In many clinical situations, the distinction between severe cellulitis and abscess may be difficult to make, especially if an abscess lies deeply within the soft tissue. In some patients an indurated cellulitis may have areas of abscess formation within it (see Chapter 16).

Severe infections occupying multiple deep fascial spaces may be in an early stage in one anatomic space, and in a more severe, rapidly progressive stage in another fascial space. A severe, deeply invading infection may pass through ever deeper anatomic spaces in a predictable fashion like a fire in a house, where there may be smoke in one room, intense heat in another room, and open flames near the source of the fire. The goal of therapy in such infections is to abort the spread of the infection in all involved anatomic spaces. These infections are discussed in detail in Chapter 16.

In summary, edema represents the earliest, inoculation stage of infection that is most easily treated. A cellulitis is an acute, painful infection with more swelling and diffuse borders. Cellulitis has a hard consistency on palpation and contains no pus. Cellulitis may be a rapidly spreading process in serious infections. An acute abscess is a more mature infection with more localized pain, less swelling, and well-circumscribed borders. The abscess is fluctuant on palpation because it is a pus-filled tissue cavity. A chronic abscess is usually slow growing and less serious than a cellulitis, especially if it has drained spontaneously to the external environment.

Medical Conditions That Compromise Host Defenses

Delineation of those medical conditions that may result in decreased host defenses is important. These compromises allow more bacteria to enter the tissues or to be more active, or they prevent the humoral or cellular defenses from exerting their full effect. Several specific conditions may compromise patients’ defenses (Box 15-1).

Uncontrolled metabolic diseases—such as uncontrolled diabetes, end-stage renal disease with uremia, and severe alcoholism with malnutrition—result in decreased function of leukocytes, including decreased chemotaxis, phagocytosis, and bacterial killing. Of these metabolic diseases, poorly controlled type 1 (insulin-dependent) and type 2 (non–insulin-dependent) diabetes are the most common immunocompromising diseases, and worsening control of hyperglycemia correlates directly with lowered resistance to all types of infections.

The second major group of immunocompromising diseases is those that interfere with host defense mechanisms, such as leukemias, lymphomas, and many types of cancer. These diseases result in decreased white cell function and decreased antibody synthesis and production.

Human immunodeficiency virus (HIV) infection attacks the T lymphocytes, affecting resistance to viruses and other intracellular pathogens. Fortunately, odontogenic infections are caused largely by extracellular pathogens (bacteria). Therefore, HIV-seropositive individuals are able to combat odontogenic infections fairly well until acquired immunodeficiency syndrome has progressed into advanced stages, when the B lymphocytes are also severely impaired. Nonetheless, care for the HIV-seropositive patient with an odontogenic infection is usually more intensive than for the otherwise normal patient.

Pharmaceuticals That Compromise Host Defenses

Patients taking certain drugs are also immunologically compromised. Cancer chemotherapeutic agents can decrease circulating white cell counts to low levels, commonly less than 1000 cells/mL. When this occurs, patients are unable to defend themselves effectively against bacterial invasion. Patients receiving immunosuppressive therapy, usually for organ transplantation or autoimmune diseases, are compromised. The common drugs in these categories are cyclosporin, corticosteroids, and azathioprine (Imuran). These drugs decrease T and B lymphocyte function and immunoglobulin production. Thus, patients taking these medications are more likely to have severe infections. The immunosuppressive effects of some cancer chemotherapeutic agents can last for up to a year after the completion of therapy.

In summary, when evaluating a patient whose chief complaint may be an infection, the patient’s medical history should be carefully reviewed for the presence of diabetes, severe renal disease, alcoholism with malnutrition, leukemias and lymphomas, cancer chemotherapy, and immunosuppressive therapy of any kind. When the patient’s history includes any of these, the patient with an infection must be treated much more vigorously because the infection may spread more rapidly. Referral to an oral-maxillofacial surgeon for early and aggressive surgery to remove the cause and initiate more intensive parenteral antibiotic therapy must be considered.

Additionally, when a patient with a history of one of these problems is seen for routine oral surgical procedures, it may be necessary to provide the patient with prophylactic antibiotic therapy to decrease the risk of postoperative wound infection. Use of the guidelines and regimens for prevention of endocarditis published by the American Heart Association and American Dental Association is a practical way to manage this problem.

Principle 5: Support Patient Medically

A patient’s systemic resistance to infection is perhaps the most important determinant of a good outcome. Host systemic resistance must be considered in three areas: immune system compromise, control of systemic diseases, and physiologic reserves.

Diseases that compromise the immune system are listed in Box 15-1. Odontogenic infections that occur in patients with immune system compromise should be treated by a specialist. Often, hospitalization and medical consultation are required. The treatment team selects therapies designed to enhance the immune response, combat the infection medically with bactericidal antibiotics, and optimize surgical management of the infection.

Many systemic diseases also reduce the ability of the patient to resist infection and to undergo treatment. In diabetes, for example, the control of blood sugar is directly correlated with resistance to infection. Host response to a significant infection increases the blood sugar levels and therefore the insulin requirements of a diabetic person. Moreover, cardiovascular diseases decrease the ability of the host to respond to the stress of infection and surgery. Therefore, optimizing control of hypertension, cardiac dysrhythmias, and atherosclerotic heart disease is an essential part of the comprehensive management of odontogenic infections. Medications may also affect the treatment of odontogenic infections. For example, the patient receiving anticoagulant therapy with warfarin (Coumadin) may need reversal of the anticoagulation before surgery can be safely performed. Patients with systemic conditions, especially of the immune, cardiovascular, respiratory, hematologic, and metabolic systems, often need sophisticated medical support from a team of specialists.

Even patients without medically compromising diseases may have reduced or altered physiologic reserves to draw upon as they combat an odontogenic infection. Children, for example, are particularly susceptible to dehydration and high fevers. Elderly patients, however, have a reduced ability to mount a fever, and yet they are susceptible to dehydration. Fever increases daily fluid requirements in the adult by about 800 mL per degree Fahrenheit per day, and daily caloric requirements by 3% to 5% per degree per day. However, temperatures up to 103° F may be beneficial in combating infections. Therefore, judicious control of highly elevated fever along with active hydration and nutritional support are important components of the management of odontogenic infections.

Because of pain and/or difficulty swallowing, patients frequently have not had adequate fluid intake, nutritional intake, or rest. During the immediate posttreatment period, patients should be encouraged to drink sufficient water or juice to require them to need to urinate regularly and to take high-calorie nutritional supplements. Patients should also be prescribed adequate analgesics for relief of pain so that they can rest. Patients should be given careful postoperative instructions and should be able to manage their self-care. The clinician is responsible to make sure patients are provided careful instructions about these important issues.

Principle 6: Choose and Prescribe Appropriate Antibiotic

Choosing the appropriate antibiotic for treating an odontogenic infection must be done carefully. When all factors are weighed, the clinician may decide that no antibiotic is necessary at all, whereas in other situations, broad-spectrum or even combination antibiotic therapy may be indicated. A variety of factors must be considered when choosing an antibiotic from the nearly 70 antibiotics currently available. Antibiotics must be viewed as a double-edged sword. Although appropriate use may result in dramatic resolution and cure of patients with infections, misuse of antibiotics provides little benefit to offset the associated risks and expense of antibiotic administration. Recent studies have shown that even the administration of oral penicillin promotes the growth of penicillin-resistant organisms in the oropharyngeal flora of the patient, the patient’s family, and even the patient’s co-workers or classmates. Therefore the following guidelines are recommended for consideration when choosing a specific antibiotic.

Principle 7: Administer Antibiotic Properly

Once the decision is made to prescribe an antibiotic to the patient, the drug should be administered in the proper dose and at the proper dose interval. The manufacturer usually recommends the proper dosage and administration. Provision of plasma levels that are sufficiently high to kill the bacteria that are sensitive to the antibiotic but are not so high as to cause toxicity is adequate. The peak plasma level of the drug should usually be at least 4 or 5 times the minimal inhibitory concentration for the bacteria involved in the infection.

Clearly, some patients stop taking their antibiotics after acute symptoms have subsided and rarely take their drugs as prescribed after 4 or 5 days. Therefore the antibiotic that would have the highest compliance would be the drug that could be given once a day for 4 or 5 days. One study has shown that for odontogenic infections a 4-day course of penicillin, combined with the appropriate surgery, was as effective as a 7-day course of the antibiotic.

Additional administration of antibiotics may be necessary in some infections that have not resolved rapidly at the clinical follow-up examination. The clinician must make it clear to the patient that the entire prescription must be taken. If for some reason the patient is advised to stop taking the antibiotic early, all remaining pills or capsules should be discarded. Keeping small amounts of unused antibiotics in medicine cabinets for the anticipated sore throat next winter should be strongly discouraged. Casual self-administration of antibiotics is not useful and may be hazardous to the health of the individual and the community.

Principle 8: Evaluate Patient Frequently

Once the patient has been treated by surgery and antibiotic therapy has been prescribed, the patient should be followed carefully to monitor response to treatment and complications. In most situations the patient should be asked to return to the dentist 2 days after the original therapy. Typically, the patient is much improved. If therapy is successful, swelling and pain decreases dramatically. The dentist should check the I&D site to determine whether the drain should be removed at this time. Other parameters, such as temperature, trismus, swelling, and the patient’s subjective feelings of improvement, should also be evaluated.

If there is not an adequate response to treatment, the patient should be examined carefully for clues to the reason for failure (Box 15-9). The most common cause of treatment failure is inadequate surgery. A tooth may have to be reevaluated for extraction, or an extension of the infection into an area not detected at the first treatment may have to be incised and drained. It may be necessary to admit such a patient to the hospital for purposes of airway security, further surgery, and intravenous antibiotic therapy.

A second reason for failure is depressed host defense mechanisms. A review of the patient’s medical history should be performed, and more careful probing questions should be asked. In addition to immunocompromising diseases, conditions that diminish physiologic reserves, such as dehydration, malnutrition, and pain, should also be considered and corrected if necessary.

A third reason for treatment failure is the presence of a foreign body. Although this is unlikely in an odontogenic infection, the dentist may consider taking a careful history and a periapical radiograph of the area to help ensure that a radiopaque foreign body is not present. Dental implants are increasingly common foreign bodies, and the ability of bacteria to find shelter from the immune system in their surface gaps and irregularities can perpetuate the infection until the implant is successfully débrided or removed.

Finally, there may be problems with the antibiotic that was given to the patient. The dentist first ascertains whether the patient has been compliant. The patient must have the prescription filled and must take the antibiotic according to directions. Many patients fail to follow the orders of their dentists as carefully as they should. Sometimes, a patient may not have the prescription filled because he or she cannot afford it. The dentist should use the most cost-effective antibiotic available and can frankly ask whether a particular prescription is affordable to the patient. Another problem to consider is whether the antibiotic reached the infected area. The penetration of antibiotics into abscess cavities is poor. Failure of the antibiotic to reach the area may be related to inadequate surgery or drainage, inadequate blood supply to the local area, or a dose that is too low to be effective against the bacteria. Another antibiotic-related problem is an incorrect bacterial diagnosis. If a culture was not performed at the initial surgical treatment or if no surgical treatment was done at the initial therapy, the dentist should obtain a specimen for C&S testing. Finally, it is possible that the wrong antibiotic was prescribed for the infection, which may be because of an inaccurate bacterial diagnosis or the increasing antibiotic resistance of oral bacteria. For example, 25% to 35% of Prevotella organisms are resistant to penicillin but rarely cause persistent infection if penicillin is given and adequate surgery is done. However, if the patient has a persistent, low-grade infection that does not resolve despite adequate surgery, prescribing an antianaerobic antibiotic such as clindamycin is appropriate.

The clinician must also examine the patient to look specifically for toxicity reactions and untoward side effects. Patients may report complaints such as nausea and abdominal cramping but may fail to associate watery diarrhea with the drug administration. Specific questioning about the expected toxicities is important to their early recognition.

The dentist should also be aware of the possibility of secondary or superinfections. The most common secondary infection encountered by dentists is oral or vaginal candidiasis. This is the result of an overgrowth of Candida organisms because the normal oral flora has been altered by the antibiotic therapy. Other secondary infections may arise as normal host flora is altered, but they are not seen with any degree of frequency in the management of odontogenic infections.

Finally, the dentist should follow the patient carefully once the infection has resolved to check for recurrent infection. Recurrence would be seen in a patient who had incomplete therapy for the infection. A variety of reasons may account for this. For example, the patient may have stopped taking the antibiotic too early. The drain may have been removed too early and the drainage site sealed too early, which reestablished the infectious process. If infection does recur, surgical intervention and reinstitution of antibiotic therapy should be considered.

Principle 1: Procedure Should Have Significant Risk of Infection

For prophylactically administered antibiotics to reduce the incidence of infection, the surgical procedure must have a high enough incidence of infection to be reduced with antibiotic therapy. Clean surgery done with strict adherence to basic surgical principles usually has an incidence of infection of about 3%. Infection rates of 10% or more are usually considered unacceptable, and the prophylactic use of antibiotics must be strongly considered for such infection-prone procedures. For the dentist doing routine office surgery, this means that most office procedures performed on healthy patients do not require prophylactically administered antibiotics. The incidence of infection after tooth extraction, frenectomy, biopsy, minor alveoloplasty, and torus reduction is extremely low; therefore, antibiotics would provide no benefit. This is true even in the presence of periapical infection, severe periodontitis, and multiple extractions.

However, several surgical factors may influence the dentist to strongly consider the use of antibiotic prophylaxis (Box 15-11): The first and most obvious factor that may lead to infection is a bacterial inoculum of sufficient size. The usual surgical procedure performed in the mouth rarely involves sufficient bacterial inoculation to cause infection, unless an acute infection with cellulitis or abscess is already present. The second factor is surgical procedures that require prolonged surgery. In hospital surgeries, the incidence of postoperative infection increases significantly with operations lasting longer than 4 hours. A third factor that may suggest the use of antibiotics is the insertion or presence of a foreign body, most commonly a dental implant. Most data seem to suggest that the use of antibiotics may decrease the incidence of infection when foreign bodies, such as dental implants, are inserted into the jaws.

The final and most important factor for most dentists in determining which patients should receive prophylactically administered antibiotics is whether the patient has depressed host defenses. Patients who have a compromised ability to defend themselves against infection should receive antibiotics prophylactically because they are likely to have a higher incidence of more severe infection. All patients receiving cancer chemotherapy or immunosuppressives should receive antibiotics prophylactically, even when minor surgical procedures are performed. Patients receiving immunosuppressives for organ transplant will be taking these drugs for the remainder of their lives and should be given preventive antibiotics accordingly. Patients receiving cancer chemotherapy will receive cytotoxic drugs for 1 year or less but should be given antibiotics prophylactically for at least a 1-year period after the cessation of their chemotherapy. This is also wise for those receiving radiation therapy to the jaw. End-stage renal disease, including patients receiving kidney dialysis, is an immunocompromising disease that requires antibiotic prophylaxis for oral surgical procedures. The most common immunocompromising disease, however, is diabetes mellitus. The incidence of postoperative infection in diabetic persons is directly correlated with elevations of blood sugar. The oral surgical management of diabetic persons based on their blood glucose is summarized in Table 15-5. The glycosylated hemoglobin test, or hemoglobin A_1c, is a good measure of the level of diabetes control over the previous 3 to 4 months. Before complex reconstructive oral surgery, such as the placement of dental implants, the dentist is wise to ensure that acceptable intermediate-term control of blood sugar has been achieved, as measured by a hemoglobin A_1c of 8% or less. The American Diabetes Association recommends a therapeutic target hemoglobin A_1c level of 7%. Withholding dental implant therapy and working with the patient’s physician can help motivate the patient to achieve good long-term control of diabetes. Although prophylactically administered antibiotics are helpful in diabetic patients, perioperative control of blood sugar levels is paramount.

Principle 2: Choose Correct Antibiotic

The choice of antibiotic for prophylaxis against infections after surgery of the oral cavity should be based on the following criteria: First, the antibiotic should be effective against the organisms most likely to cause infection in the oral cavity. As previously discussed, the facultative streptococci are usually the originally invading organism in oral infection. Second, the antibiotic chosen should be a narrow-spectrum antibiotic.

By using a narrow-spectrum antibiotic, the disadvantage of altering host flora is minimized. Third, the antibiotic should be the least toxic antibiotic available for the patient. Finally, the drug selected should be a bactericidal antibiotic. Because many of the routine prophylactic uses of antibiotics in the dental office are for patients with compromised host defenses, it is important that the antibiotic effectively kill the bacteria.

Taking into account these four criteria, the antibiotic of choice for prophylaxis before oral surgery is penicillin or amoxicillin. These two antibiotics are effective against the causative organism (i.e., Streptococcus), are narrow-spectrum, have low toxicity, and are bactericidal. For patients allergic to penicillin, the best choice is clindamycin. Clindamycin is fairly effective against oral streptococci and is narrow-spectrum, but it is bacteriostatic. The third choice for oral administration for prophylaxis is azithromycin. Azithromycin is reasonably effective against the usual organisms and is narrow-spectrum, but it is also bacteriostatic.

Principle 3: Antibiotic Plasma Level Must Be High

When antibiotics are used prophylactically, the antibiotic level in the plasma must be higher than when antibiotics are used therapeutically. The peak plasma levels should be high to ensure diffusion of the antibiotic into all of the fluid and tissue spaces where the surgery is going to be performed. The usual recommendation for prophylaxis is that the drug be given in a dose at least 2 times the usual therapeutic dose. Use of the same prophylactic doses recommended by the American Heart Association for prophylaxis of infective endocarditis is reasonable. For penicillin or amoxicillin, this is 2 g; for clindamycin, 600 mg; and for azithromycin, 500 mg.

Principle 4: Time Antibiotic Administration Correctly

For the antibiotic to be maximally effective in preventing postoperative infection, the antibiotic must be given 2 hours or less before the surgery begins. The time of dosing before surgery varies by the route used, allowing for absorption of the antibiotic into the tissues at the time of wounding. For the oral route, this is usually 1 hour; with the intravenous route, a much shorter preoperative dosing interval is possible. This principle has been clearly established in many animal and human clinical trials. Antibiotic administration that occurs after surgery is greatly decreased in its efficacy or has no effect at all on preventing infection; there is evidence to indicate that prophylactically administered antibiotics given 2 hours or more after surgery may increase the risk of wound infection.

If the surgery is prolonged and an additional antibiotic dose is required, intraoperative dose intervals should be shorter (i.e., one half the usual therapeutic dose interval). Therefore, penicillin and clindamycin should be given every 3 hours. This ensures that the peak plasma levels will stay adequately high and avoids periods of inadequate antibiotic levels in the tissue fluids.

Principle 5: Use Shortest Antibiotic Exposure That Is Effective

For the antibiotic prophylaxis to be effective, the antibiotic must be given before the surgery begins, and adequate plasma levels must be maintained during the surgical procedure. Once the surgical procedure is completed, continued antibiotic administration produces little if any benefit. If the procedure is a short operation, a single preoperative dose of antibiotics is adequate. A plethora of animal and human clinical data demonstrates that the prophylactic use of antibiotics is necessary only for the time of surgery; after closure of the wounds and formation of the blood clots, migration of bacteria into the wound and underlying tissues occurs at such a low level that additional antibiotics are not necessary.

Summary

The use of antibiotics for prophylaxis of postoperative wound infection may be effective. It may reduce patient pain, morbidity, cost, and total antibiotic use. Appropriate antibiotic prophylaxis does little to alter host flora. Most dental procedures on healthy patients do not require antibiotic prophylaxis. A few select patients who are to undergo long surgical procedures or the insertion of foreign bodies, such as dental implants, should be considered for prophylaxis. Patients who have compromised host defenses because of poorly controlled metabolic diseases or certain diseases that interfere with host defenses or who are taking drugs that suppress the immune system should also be given prophylactic antibiotics. The drug of choice is a narrow-spectrum antibiotic that is effective against causative organisms, is nontoxic, and is bactericidal. Penicillin fits these criteria the best.

When the antibiotic is given, it should be taken before the surgery begins, at a normal dose twice that of therapeutically administered antibiotics. If the surgery is prolonged, interim doses at half the normal dose interval should be used. High plasma levels should be maintained during the surgical procedure, but no additional antibiotics are necessary after surgery.

Prophylaxis Against Infectious Endocarditis

Historically, the rationale for antibiotic prophylaxis of infectious endocarditis (IE) after dental procedures has been based on the following facts: bacteremia has been shown to cause IE; viridans-group streptococci are part of the normal oral flora and have been commonly found in IE; dental procedures can cause bacteremias because of Streptococcus viridans; a large number of case reports associate dental procedures with subsequent IE; S. viridans is generally susceptible to the antiobiotics recommended for prophylaxis of IE; antibiotic prophylaxis prevents experimental endocarditis in animals because of S. viridans; and the risk of significant adverse reaction to the antibiotic is low in an individual patient, and the morbidity and mortality of IE are high. When this occurs, the patient must be treated in the hospital with high doses of intravenous (IV) antibiotics for prolonged periods. Often, the damaged native heart valve must be surgically replaced with a prosthetic valve. Although initial recovery from bacterial endocarditis approaches 100%, recurrent episodes reduce the 5-year survival rate of patients with this disease to approximately 60%.

Recent evidence puts into question the likelihood, however, that prophylactic antibiotics prevent IE in human beings. Antibiotics do no consistently prevent bacteremias after dental procedures. Bacteremias after chewing, toothbrushing, and other daily activities occur far more frequently than after dental procedures. Endocarditis has been shown to occur despite appropriate antibiotic prophylaxis for dental procedures. Only a small proportion of IE cases are from dental procedures, and very few cases of IE would be prevented by antibiotic prophylaxis for dental procedures, even it if were 100% effective.

The American Heart Association has had formal recommendations for the prevention of IE after dental treatments since 1960. The latest formal recommendations appeared in May 2007. Dentists must stay abreast of revised recommendations as they are published by the American Heart Association and the American Dental Association. These new guidelines take into account that a very small number of cases of IE are caused by dental procedures and can be prevented by antibiotic prophylaxis. New emphasis has been correctly placed on the establishment and maintenance of optimum oral health in patients with increased risk for IE.

The new guidelines indicate prophylaxis only for the patients at highest risk of endocarditis, including those with previous endocarditis, prosthetic heart valves, cyanotic congenital heart defects that have not been repaired or have remaining partial defects after repair, and heart transplant patients with valvulopathy. This will significantly decrease the number of dental patients for whom prophylaxis is indicated. A list of the conditions that pose the highest risk of endocarditis can be found in Box 15-13.

Recent evidence also indicates that the magnitude of bacteremia caused by a given dental procedure is not necessarily correlated with the incidence of IE. Therefore the new guidelines have simplified the description of dental procedures for which antibiotic prophylaxis should be used to the following description: “All dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa” (Box 15-14). Prophylaxis is not required for routine local anesthetic injections through noninfected tissue, dental radiographs, placement of removable prosthodontic or orthodontic appliances, adjustment of orthodontic appliances, placement of orthodontic brackets, shedding of deciduous teeth, and bleeding from trauma to the lips or oral mucosa (Box 15-15).

Bacterial endocarditis prophylaxis is achieved for most routine conditions with the administration of 2 g of amoxicillin orally ½ to 1 hour before the procedure (Table 15-6). Amoxicillin is the drug of choice because it is better absorbed from the gastrointestinal tract and provides higher and more sustained plasma levels. Amoxicillin is an effective killer of viridans-group streptococci, which include the organisms that most commonly causes IE after dental procedures.

For patients who are allergic to penicillin, two alternative drugs have been recommended. The first recommended drug is clindamycin, with a dose of 600 mg orally 1 hour before the surgery. If the patient’s allergy to penicillin is mild and not of an anaphylactic type, a first-generation cephalosporin, such as cephalexin, may be prescribed. Although erythromycin is no longer recommended, the newer macrolide antibiotics, azithromycin or clarithromycin, are acceptable alternative drugs. If the patient is unable to take oral medication, parenteral administration can be used.

For the pediatric patient, the dose of the drugs that are given must be reduced. The recommendations include clear guidelines for proper pediatric dosing (see Table 15-6).

Some patients at risk for bacterial endocarditis may be taking daily doses of penicillin to prevent recurrence of rheumatic fever or may already be taking an antibiotic for other reasons. In these patients, the streptococci may be relatively resistant to penicillin. The recommendation for this situation is that the dentist should use clindamycin, azithromycin, or clarithromycin for endocarditis prophylaxis. The cephalosporins should be avoided because of possible cross-resistance with the penicillins. If possible, the procedure should be postponed until 10 or more days after the antibiotic is completed, thus allowing a more normal oral flora to be reestablished.

If a particular patient requires a series of dental treatments that requires antibiotic prophylaxis, a period of 10 or more days between appointments is appropriate. The reason for the interval is that the administration of antibiotics for several days or more continuously may promote colonization of the patient by bacteria that are resistant to the antibiotic being given, thus making prophylaxis more likely to fail. The 10-or-more day antibiotic-free period may allow antibiotic-sensitive organisms to repopulate the oral flora. On the other hand, it has been shown that baseline antibiotic resistance levels are not reestablished for several months after a course of antibiotics. For this reason, the number of dental visits should also be minimized, consistent with the patient’s tolerance level.

Occasionally, unexpected bleeding may occur during dental treatment in a patient who is at risk for endocarditis, or a patient may not inform the dentist of the indication for antibiotic prophylaxis before the beginning of the procedure. In this situation, appropriate antibiotic prophylaxis should be administered as soon as possible but definitely within 2 hours after the procedure. Prophylaxis given longer than 4 hours after the bacteremia has limited prophylactic benefit.

Patients at risk for IE should have a comprehensive prophylaxis program that includes excellent oral hygiene with excellent periodic professional care. Special care should be taken for the establishment of an effective preventive program, and all incipient dental and periodontal disease should be treated. If surgery is required, the mouth can be rinsed preoperatively with an antibacterial agent, such as chlorhexidine. Preoperative oral antiseptic rinses have been shown to reduce the magnitude of bacteremias (the number of bacteria entering the bloodstream), although they are not a substitute for antibiotic prophylaxis.

Finally, it is important for the dentist to understand that even when appropriate measures are taken to prevent bacterial endocarditis, it may still occur. Patients should be informed of this and advised to return to the dentist or to their primary care physician if any of the signs and symptoms of bacterial endocarditis, especially fever and malaise, occur.

Prosthetic valve endocarditis occurs when the tissue around the cardiac valve implant becomes infected. Such infections are caused by the same bacteria that cause typical native valve endocarditis. Prosthetic valve endocarditis is a much more serious illness than native valve endocarditis because the loosening of the heart valve may result in death. The 1-year survival rate for patients who have prosthetic valve endocarditis is about 50%. The American Heart Association currently states that the standard oral regimens are adequate for most patients with prosthetic heart valves.

Prophylaxis in Patients with Other Cardiovascular Conditions

Several other cardiovascular conditions require the clinician to consider the administration of prophylactic antibiotics for the prevention of metastatic infection. In coronary artery bypass grafting (CABG), the coronary arteries are reconstructed with vascular grafts. Because CABG does not predispose patients to metastatic infection, these patients should not be given prophylactic antibiotics before a dental procedure is performed.

Patients with a transvenous pacemaker have a battery pack implanted in their chests, with a thin wire that runs through the superior vena cava into the right side of the heart. These patients usually do not require prophylactic antibiotics when dental procedures are performed. Similarly, coronary artery angioplasty with or without stent placement is not an indication for endocarditis prophylaxis. However, consultation with the patient’s cardiologist may be used to confirm that this is the best management.

Patients receiving renal dialysis frequently have an arteriovenous shunt surgically constructed in their forearms to provide the dialysis team ready access to the bloodstream. Metastatic infection may occur in these shunts after bacteremia. Therefore the dentist should contact the patient’s nephrologist or renal dialysis team to discuss the best management.

Patients who have hydrocephaly may have decompression with ventriculoatrial shunts. Because these shunts may induce valvular dysfunction, antibiotic prophylaxis may be required. Consultation with the patient’s neurosurgeon should be considered.

Patients who have had severe atherosclerotic vascular disease and have had alloplastic vascular grafts placed to replace portions of their arteries do not appear to be at risk for metastatic infection from dental procedures. Therefore the American Heart Association does not recommend antibiotic prophylaxis for nonvalvular cardiovascular devices, including coronary artery stents and vena caval filters. The exception to this rule is for incision and drainage of abscesses at other sites, including the oral cavity.

Prophylaxis Against Total Joint Replacement Infection

Patients who have undergone total replacement of a joint with a prosthetic joint may be at risk for hematogenous spread of bacteria and subsequent infection. These late prosthetic joint infections result in severe morbidity because the implant is usually lost when infections occur. There has been great concern that the bacteremia caused by tooth extraction may result in such infections. However, the recent literature suggests that bacteremias from oral procedures are not likely to cause prosthetic joint infections. It appears that the bacteremia after oral surgery is of a transient nature and does not expose the implant and periimplant tissues to bacteria long enough to cause infection.

Instead it appears that the hematogenous spread of prosthetic joint infections is caused by chronic infections elsewhere in the body that result in chronic septicemias. These infections are typically urogenital, gastrointestinal, pulmonary, or skin infections, but established odontogenic infections may also cause a septicemia of sufficient magnitude to cause a total joint infection. Patients with orthopedic pins, plates, and screws do not need antibiotic prophylaxis.

In July of 2003 the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) issued a revised joint recommendation concerning the management of patients with prosthetic total joints. The recommendations of the ADA and AAOS recognize that most patients with a prosthetic joint are not at risk for joint infection after a dental surgical procedure. Instead the guidelines identify the high-risk patients who are potentially susceptible to such infections (Box 15-16). Likewise, it identifies those procedures that are most likely to cause joint infections and therefore require prophylaxis (Box 15-17). The joint statement recommends specific antibiotic regimens to help prevent infection in the susceptible patient who is undergoing one of the procedures that require prophylaxis (Table 15-7). Ultimately however, the revised guidelines make the following statement: “Practitioners must exercise their own clinical judgment in determining whether or not antibiotic prophylaxis is appropriate.”

When the dentist decides to provide antibiotic prophylaxis of prosthetic joint infection, the recommended antibiotics are a first-generation cephalosporin and amoxicillin. For patients who are allergic to penicillin, clindamycin is recommended. As with bacterial endocarditis prophylaxis, only a single preoperative dose is recommended, with no follow-up doses. If patients are unable to take oral medication, a parenteral regimen is also suggested (Box 15-18).

If a patient who has a total joint replacement needs treatment of an infection, aggressive therapy for the infection is necessary to prevent seeding of the bacteria into the prosthesis, causing odontogenic infection of the prosthetic joint. This aggressive treatment should include extraction, I&D, and the use of high-dose bactericidal antibiotics, possibly given IV. The clinician should strongly consider performing C&S testing because if a prosthetic joint infection does occur, it would be useful to know which bacteria are likely the causative organisms along with their antibiotic sensitivity.

When there is disagreement between the dentist, the patient, or the patient’s physician over the need for antibiotic prophylaxis, clear communication between all parties is required to clarify all relevant facts and scientific data and to arrive at a consensus. Ultimately, the dentist is responsible for his or her own treatment decisions and should not render care that he or she thinks is not in the best interest of the patient.

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