Chemoprophylaxis of Bacterial Endocarditis recommended
by General Dental Practitioners in Spain

TOMÁS-CARMONA I, DIZ-DIOS P, LIMERES-POSSE J, OUTUMURO-RIAL M, CAAMAÑO-DURÁN F, FERNÁNDEZ-FEIJOO J, VÁZQUEZ-GARCÍA E. CHEMOPROPHYLAXIS OF BACTERIAL ENDOCARDITIS RECOMMENDED BY GENERAL DENTAL PRACTITIONERS IN SPAIN. MED ORAL 2004;9:56-62.

SUMMARY

The aim of this study was to assess the current practice of antibiotic prophylaxis of Bacterial Endocarditis (BE) among General Dental Practitioners (GDPs) in Spain.
GDPs were asked over the telephone by a fictitious patient what antibiotic prophylaxis they would administer to an "at risk" patient for BE before a tooth extraction. Four hundred randomly selected Spanish GDPs were surveyed, 200 of them were asked about BE prophylaxis in penicillin non-allergic patients and the remaining 200 in penicillin allergic patients.
Of the GDPs surveyed, 182 (45.5%) did not recommend any prophylactic treatment; 74.7% of those stated that an oral examination before treatment was needed and 25.3% referred the patient to his/her physician or cardiologist for further advice. Of the 97 GDPs who recommended antibiotics to penicillin non-allergic patients, only 30 (30.9%) suggested the prophylactic guidelines proposed by the American Heart Association or the British Society for Antimicrobial Chemotherapy. For penicillin allergic patients, 68.2% of the GDPs prescribed erythromycin as the antibiotic of first choice, while 17.6% of the GDPs prescribed clindamycin. Nonetheless, fewer than 30% administered both antibiotics with the adequate dosages.
These results show important gaps in the knowledge of antibiotic prophylaxis for "at risk" patients before dental procedures among Spanish GDPs.

Key words: Bacterial endocarditis, antibiotic prophylaxis, general dental practitioner.

INTRODUCTION

Previous reports have described a possible oral portal of entry in 14-20% of patients with Bacterial Endocarditis (BE) (1-5). Although, it is impossible to predict which patients will develop this infection or which dental procedures will be responsible for it, the use of antibiotic prophylaxis in "at risk" BE patients who are undergoing certain dental manipulations is a reasonably well accepted practice (6). Various committees of experts have proposed different guidelines and antibiotic prophylactic regimens of BE (7-16) (Table 1). These recommendations have been reviewed and periodically modified, on the basis of experimental animal models (17), pharmacokinetic studies (18), bacterial susceptibility studies (19), retrospective analyses of BE series (20), studies of procedure-related bacteraemia (21) and the efficacy of antimicrobial prophylaxis against bacteraemia (22).

Table 1. BE antibiotic prophylaxis recommended for dental procedures in
patients "at risk" (7-16).
(a) Antibiotic of choice for penicillin non-allergic patients.
(b) Antibiotic of choice for penicillin allergic patients.
AHA=American Heart Association.
BSAC=British Society for Antimicrobial Chemotherapy.

The Endocarditis Working Party of the British Society for Antimicrobial Chemotherapy (BSAC) published an antibiotic prophylaxis protocol of BE in 1982 (9). This was reviewed and modified in 1986 (11), 1990 (13) and 1993 (14). Since 1955 (23), the American Heart Association (AHA) has made 8 sets of recommendations regarding the prevention of BE. The most recent guidelines were published in 1997 (16). Currently, both societies have established a precise description of the "at risk" BE groups and the dental procedures which require antibiotic prophylaxis, recommending a single-dose antibiotic regimen (14,16) (Table 1).

The aim of this study was to assess the current practice of BE prophylaxis in a group of General Dental Practitioners (GDPs) in Spain.

MATERIAL AND METHODS

In the present study the information was collected from 400 randomly selected Spanish GDPs who were asked over the telephone which antibiotic prophylactic protocol they would administer to an "at risk" patient for BE before a tooth extraction. A fictitious patient called relating the following question: "A month ago, during a trip, I started to suffer from toothache and I was prescribed an antibiotic in an Emergency Unit. The doctor who had my check-up done, advised me repeatedly that in case I needed a tooth extraction I should be administered an antibiotic prophylaxis since I am carrier of prosthetic mitral valve. Which drug should I be administered before undergoing the tooth extraction?".

Of the 400 GDPs surveyed, 200 were asked about BE prophylaxis in penicillin non-allergic patients and the remaining 200 in penicillin allergic patients. For the assessment of the different antibiotic regimens proposed, the AHA of 1990 (12) and 1997 (16), and the BSAC of 1993 (14) guidelines were followed to classify the recommended prophylactic practice.

RESULTS

Of the 400 GDPs surveyed, 182 (45.5%) did not recommend any prophylactic treatment; 74.7% of those stated that an oral examination before treatment was needed and 25.3% referred the patient to his/her physician or cardiologist for further advice. In penicillin non-allergic patients only 97 GDPs recommended antibiotics: 25 (25.8%) applied incomplete BE prophylaxis (only mentioned the antibiotic), 42 (43.3%) applied incorrect BE prophylaxis (due to the antibiotic choice, dosage or duration of application not corresponding to any of the available protocols), and only 30 (30.9%) recommended a correct BE prophylaxis (17 replies coincided with the AHA protocol of 1990, 11 with the AHA protocol of 1997 and 2 with the BSAC protocol of 1993) (Table 2).

Table 2. BE antibiotic prophylaxis recommended by Spanish GDPs for penicillin
non-allergic and allergic patients.
* Of the 200 GDPs surveyed, 97 recommended some type of prophylactic
protocol.
** Of the 200 GDPs surveyed, 121 recommended some type of prophylactic
protocol.
a- Only mentioned the antibiotic.
b- The antibiotic choice, dosage or duration of application not corresponded
to any of the available protocols.
c- The AHA of 1990 and 1997, and the BSAC of 1993 guidelines were considered
correct prophylactic practice.

In penicillin allergic patients, only 121 GDPs recommended some type of prophylactic protocol. The chosen antibiotic was erythromycin in 68.2% of the cases, in 17.6% clindamycin and in 14.2% others. The recommended BE prophylaxis protocols were classified as: 44 (36.4%) as incomplete, 43 (35.3%) as incorrect and only 34 (28.3%) as correct (19 replies coincided with the AHA protocol of 1990 and 15 with the AHA protocol of 1997-BSAC protocol of 1993) (Table 2).

DISCUSSION

In the literature, there are several reports of inquiries carried out in different countries on awareness of GDPs about BE chemoprophylaxis before certain dental procedures (24-34) (Table 2). All these reports have a common methodological bias, derived either from the application of standardized questionnaires sent by post (24,25), or through telephone interviews with a prior certified letter explaining the background and importance of the survey (29,30). In the present study, the researcher put forward to the GDP a "hypothetical clinical case" over the telephone, without revealing at any moment the objective of the inquiry.

Despite the fact that the AHA comments on the underlying cardiac conditions and the dental procedures which require antibiotic prophylaxis in its latest report (16), Strom et al. (35) found out that BE patients were not more likely than controls to receive dental therapy during the preceding 3 months. As a consequence, these authors (35) suggested that dental procedures do not constitute a risk factor for BE, even in patients with underlying cardiac diseases. Due to the existing controversy, Durack (36), in an editorial published in Annals of Internal Medicine in 1998, proposed that prophylaxis should not be recommended for most dental procedures except tooth extractions and gingival surgery, and did not recommend it for most underlying cardiac conditions except prosthetic valves and previous BE.

Although more than 50% of the GDPs consider that the responsibility for appropriate BE prophylaxis before dental therapy ultimately reverts back to them (25), physician consultation in patients who are or may be at risk of BE is a common practice (27,37,38), carried out by more than 25% of the surveyed GDPs. Nonetheless, Tomás et al. (39) found that 28% of Spanish cardiologists/internists were unaware of the BE prophylaxis guidelines for dental patients "at risk".

In contrast to previous reports (27,29), in our study nearly 100% of GDPs prescribed oral amoxycillin for penicillin non-allergic patients. This antibiotic was recommended by the AHA since it is better absorbed from gastrointestinal tract and provides higher and more sustained serum levels that ampicillin and penicillin V (16). On the other hand, in accordance with older studies (26,27), erythromycin (almost 70%) continues to be the preferred antibiotic for penicillin allergic patients among Spanish GDPs. However, in the later prophylactic protocols from the AHA (16) and from the BSAC (14), clindamycin has been recommended as the antibiotic of choice in patients allergic to penicillin.

Several studies on GDPs compliance with BE prophylaxis showed that in "at risk" patients, the administered dosage and timing of antibiotics all differed markedly (24-34). The percentage of replies which agreed with the recommendations of the AHA or BSAC ranged between 1.6%-96% (Table 3). In our series, only one third of GDPs whom recommended some prophylactic treatment, the dosage and duration of drug administration corresponded to one of the available recommendations. The remaining almost 70% of the surveyed GDPs only named the antibiotic, recommended it for too long either before or after the procedure, or they used inadequate dosages of antibiotics or the wrong ones.

Table 3. Main inquiries about GDPs compliance with BE antibiotic prophylactic
recommendations (24-34).
* The AHA and the BSAC guidelines were considered correct prophylactic
practice.
(a) Prophylaxis for patients with heart disease and with prosthetic heart valves,
respectively.
(b) Prophylaxis for penicillin non-allergic and allergic patients, respectively.
(c) This group was formed by dentists, chest physicians and ear, nose and throat
specialists.
(d) Prophylaxis for medically compromised patients.

Earlier studies detecting low compliance found this to be presumably associated to the unacceptability of injectable antibiotics (40). Holbrook et al. in 1987 (41) showed a marked change in practice with widespread adoption of the single-dose oral amoxycillin regimen; this was the preferred protocol for 63% of GDPs. Forbat et al. (30) found that 96% of English GDPs would prescribe the antibiotic regimen recommended by the BSAC in 1993. Recently, Epstein et al. (34) in a large survey performed in Canada found that more than 80% of GDPs administered the current AHA prophylaxis protocol. It probably reflects the greater ease of compliance and simplicity of administration associated to the single-dose treatment compared to those previously used. On the contrary, our results showed that among Spanish GDPs there was an underrating towards single-dose protocols, since they were only recommended by 13.4%-12.3% (for penicillin non-allergic and allergic patients respectively) of the GDPs surveyed.

The most frequent protocol suggested was that of the AHA from 1990 (12).

The implication of certain dental procedures or oral infections in the development of BE, the severity of this cardiological disease, the ease and efficiency of the preventive prophylactic protocols and the severe legal repercussions (42), call for knowledge of GDPs on the updated guidelines of BE antibiotic prophylaxis. The results of this survey highlight an important lack of knowledge among Spanish GDPs about the correct antibiotic prophylaxis for "at risk" patients. No clear consensus from the literature can partly explain the existing confusion among GDPs over which guidelines are correct and more updated.

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