Chapter 6
Managing Patients Who Require Antibiotic Cover
Aim
The aim of this chapter is to outline the reasons for prescribing antibiotic cover and to describe the most currently proposed regimes.
Outcome
After reading this chapter, the practitioner will be aware of the conditions and dental treatment that require antibiotic cover, the suggested regimes, and the current dilemmas surrounding antibiotic cover. The practitioner should be aware that guidelines change and they have a professional responsibility to keep up to date.
Introduction
The requirement for antibiotic cover (abc) is one of the more confusing areas in dentistry with different regimes adopted in different countries, in different areas of the UK or even between departments within the same hospital. National guidelines are produced by the Working Party of the British Society for Antimicrobial Chemotherapy (BSAC) and published in the Dental Practitioners’ Formulary. The latest proposed UK guidelines have simplified recommended antibiotic cover regimes (Table 6-1).
| High-risk cardiac factors requiring antibiotic prophylaxis | Previous infective endocarditis Cardiac valve replacement surgery, i.e. mechanical or biological prosthetic valves Surgically constructed systemic or pulmonary shunt or conduit |
| Dental procedures requiring antibiotic prophylaxis | All dental procedures involving dento-gingival manipulation |
| Antibiotic regimens for endocarditis prophylaxis | All Preoperative mouth rinse with chlorhexidine gluconate 0.2% (10 ml for 1 minute) |
| No allergies Adults and children > 10 years Amoxicillin 3 g orally one hour before dental procedure > 5 < 10 years of age 1.5 g < 5 years of age 750 mg |
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| If allergic to penicillin Adults and children > 10 years Clindamycin 600 mg orally one hour before dental procedure > 5 < 10 years of age 300 mg < 5 years of age 150 mg |
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| Allergic to penicillin and unable to swallow capsules Adults and children > 10 years Azithromycin 500 mg orally one hour before dental procedure > 5 < 10 years of age 300 mg < 5 years of age 200 mg |
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| Intravenous regimens for dental treatment (when considered expedient) |
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| Adults and children > 10 years A single IV dose of 1 g amoxicillin given just before the procedure or at induction of anaesthesia > 5 < 10 years of age 500 mg < 5 years of age 250 mg |
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| If allergic to penicillin Adults and children > 10 years A single IV dose of 300 mg clindamycin given at least 10 minutes before the procedure or at induction of anaesthesia > 5 < 10 years of age 150 mg < 5 years of age 75 mg |
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| Where a course of treatment involves several visits Visits should be at intervals of at least 14 days to allow healing of oral mucosal surfaces Where further dental procedures cannot be delayed, the antibiotic regimen should alternate between amoxicillin and clindamycin |
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| If allergic to penicillin Seek expert advice |
Source: Gould FK, Elliott TSJ, Foweraker J, et al. Report of the Working Party of the British Society for Antimicrobial Chemotherapy: Guidelines for the Prevention of Endocarditis. J Antimicrob Chemother 2006;57:1035–1042.
In theory, the provision of antibiotic cover for dental treatment is linked to the prevention of infective endocarditis. However, there is a lack of any supporting evidence that dental treatment leads to infective endocarditis. A prospective double-blind trial is needed to evaluate the benefit of prophylactic antibiotics. This is unlikely to happen due to ethical considerations and the large numbers of people required to provide any significant findings.
Infective Endocarditis
Infective endocarditis carries a high risk of morbidity and mortality. Rapid diagnosis, effective treatment, and prompt recognition of complications are essential to good patient outcome. Appropriate action for its prevention in high-risk patients is paramount as infective endocarditis is an uncommon, but potentially fatal, infection of the endocardium or vascular endothelium. It has a reported incidence of 1500 cases a year in England and Wales and this is thought to be increasing due to:
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children with congenital heart disease surviving into adulthood
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an ageing population, with damaged hearts, surviving longer, and
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an increase in the number of intravenous drug users.
Infective endocarditis develops in vegetations formed on the valve leaflets or other sites on the endocardium where damage has occurred. The initial lesion is a platelet thrombus. Micro-organisms accumulate and multiply in the thrombus and more platelets and fibrin are deposited over the organisms. Eventually infective emboli break off to be deposited in different sites of the body. These septic emboli can cause gangrene of the fingers, stroke, myocardial infarction and pulmonary infarction. Other clinical features include fever, chronic renal failure and a new or changing heart murmur as the virulent organisms rapidly destroy the valve cusp producing ulceration and regurgitation.
Most commonly, infective endocarditis develops in valves which have been damaged due to rheumatic fever or congenital heart disease, but prosthetic valves can also be affected. Patient susceptibility to infective endocarditis is dependent on the underlying cardiac condition and the resulting changes to haemodynamic flow. The more severe the turbulence the more damage there is to the endothelium and the greater the risk of infective endocarditis. Small defects are more likely to cause turbulence than large ones, and surgically repaired atrial and ventricular septal defects are thought to be low risk. Patients who have had one episode of infective endocarditis are at increased risk of another episode.
Mortality varies depending on the infecting organism and is higher when a prosthetic valve is infected. Oral streptococci, and hence dental treatments, have been implicated in 47.5% of confirmed cases. Other commonly involved bacteria include enterococci and staphylococci, fungi and the haemophilus group. In intravenous drug users, where the risk arises from injecting drugs being made up with non-sterile water, more unusual microorganisms such as Candida, Aspergillus and Brucella are involved.
Risk of Infective Endocarditis from Dental Treatment
Differing views have been held as to which cardiac conditions put patients undergoing invasive dental treatment at risk of developing infective endocarditis. The predisposing conditions and special risk patients are shown in Table 6-2.
| Conditions predisposing to infective endocarditis |
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