The American Heart Association (AHA)recently updated its guidelines regarding which patients should take a precautionary antibiotic to prevent infective endocarditis. The guidelines published in circulation: Journal of the American Heart Association, are based on a growing body of scientific evidence shows that for most people the risks of taking prophylactic antibiotics for certain procedures outweigh the benefits. These guidelines represent a major change in philosophy. The new guidelines show that taking preventative antibiotics is not necessary for most patients and in fact might create more harm than good. Unnecessary use of antibiotics causes allergic reactions and may cause dangerous antibiotic resistance. Only the people at greatest risk of bad outcomes from infective endocarditis – an infection of the heart and the lining or the heart valves – should receive short-term preventative antibiotics before common surgical procedures.

These guidelines are abstracted from the article published in circulation 2007:116:1736/1754.

Infective endocarditis is an uncommon but life-threatening infection. Since the last American Heart Association publication on prevention of infective endocarditis in 1997 many publications have questioned the efficacy of antibiotic prophylaxis to prevent infective endocarditis in patients who undergo a dental, gastrointestinal or genitourinary tract procedure and have suggested that the AHA guidelines be revised.

Various international bodies with an interest in revising the guidelines reviewed all the published data and then got together and published this new data. The revised guidelines for infective endocarditis prophylaxis were therefore issued and published.

A summary of major changes in updated document

1. Bacteraemia resulting from daily activities is much more likely to cause infective endocarditis than bacteraemia
    associated with a dental procedure.
2. Antibiotic prophylaxis is not recommended based solely on an increased long-term risk of acquisition of infective
    endocarditis.
3. Antibiotic prophylaxis for infective endocarditis is recommended now only for patients with –
          •  Prosthetic cardiac valves or prosthetic material used for cardiac valve repair
          •  Previous infective endocarditis
          •  Congenital heart disease – unrepaired cyanotic and general heart disease including palliative shunts and
             conduits, completely repaired congenital heart defects with prosthetic material or device either placed by
             surgery or by catheter intervention during the 1st 6 months after the procedure, repaired congenital heart
             disease with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device
             which inhibits endothelialisation.
          •  Cardiac transplantation recipients who develop cardiac valvulopathy.

Except for the conditions listed above antibiotic prophylaxis is no longer recommended for any other form of congenital heart disease.

Approximately 30% of the flora of the gingival crevice is streptococci ,mostly of the viridans group. Of more than 100 bacterial species recovered from blood cultures after dental procedures the most prevalent are the viridans group streptococci.

The role of duration of bacteraemia and size of the inoculum on the risk of acquisition of endocarditis is uncertain. Early studies reported that sequential blood cultures were positive for up to 10 minutes after tooth extraction and that the number of positive blood cultures dropped sharply after 10-30 minutes. Generally the body’s natural defenses are adequate to kill the amount of bacteria introduced by the above procedures.

No prospective, randomized, placebo-controlled study yet exists on the efficacy of antibiotic prophylaxis to prevent infective endocarditis in patients who undergo a dental procedure.

Data from published retrospective or prospective case controlled studies are limited by low incidence of infective endocarditis, wide variation in the type and severity of underlying cardiac condition and a large variety of invasive dental procedures and dental disease states. There is one patient case controlled study performed among patients for whom prophylaxis was recommended. 5 of the 20 cases of infective endocarditis occurred despite receiving prophylactic antibiotic therapy.

The estimated risk of endocarditis from a dental procedure has been determined to be 1 case of endocarditis per 14 million dental procedures. This however, increases if there was underlying heart disease,

mitral valve prolapse – 1:1 million procedures,
congenital heart disease – 1:475,000 procedures,
rheumatic heart disease – 1:142,000 procedures,
presence of a prosthetic valve – 1:100,000 procedures and for patients with
previous endocarditis – 1:95,000 procedures.

Conclusions in the article from which date this article is abstracted is highly recommended and available on the web at http://circ.ahajournals.org/cgi/reprint/circulationAHA:106:183095 by Wilson et al. Circulation 2007:116(15):1736 - 1754.

Antibiotic prophylaxis for the above patients is recommended for all dental procedures that involve manipulation of gingival tissue, or the peri-apical region of teeth or appropriation of the oral mucosa.

The following procedure and events DO NOT need prophylaxis –

          •  Routine anaesthetic injections through non-infected tissue, taking 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.

Antibiotic prophylaxis is reasonable for procedures on respiratory tract or infected skin, skin structures or mucosal tissue only for patients with underlying cardiac conditions associated with the highest risk of adverse outcomes and endocarditis as listed above.

Antibiotic prophylaxis solely to prevent infective endocarditis is not recommended for patients undergoing genitourinary or gastrointestinal tract procedures.

Additionally antibiotic prophylaxis is not recommended for patients undergoing vaginal delivery, hysterectomy and tattooing or body piercing.

Regimens for a dental procedure
Regimen: single dose 30-60 minutes before procedure.

** Cephalosporins should not be used in an individual with a history of anaphylaxis, angioedema, urticaria with penicillin or Ampicillin.

These guidelines relate to patients who are otherwise well undergoing elective procedures.

Patients who have obvious infections eg skin infections – furuncles and the like, and infection of any other organ system should receive appropriate antibiotics in adequate doses until the infection is cleared. These patients should also delay having elective procedures if at all possible until the infection is cleared and they have completed their antibiotic therapy and for a period of 2 weeks after they have completed their course of antibiotic therapy.