Research task on infective endocarditis

Background on bacterial endocarditis

Infective endocarditis is an infection of the endocardium (internal surface of the heart). Effects may include:

1.       Severe valvular insufficiency

2.       Congestive heart failure

3.       Myocardial abscess

4.       Death if left untreated

Infective endocarditis is a relatively uncommon illness with high morbidity and mortality. The incidence in Australia is approximately five cases per 100 000 person–years and the in-hospital mortality is 15% to 20%

Bacteraemia associated with dental procedures usually involves viridans group streptococci, which are known to cause infective endocarditis. Traditionally, the presence of 'significant bleeding' associated with a dental procedure was assumed to be an indication of bacteraemia and hence a need for prophylaxis; however, studies show that bleeding is a poor indicator of bacteraemia from dental procedures. The key factors of a bacteraemia of oral origin are the incidence, magnitude and duration of viridans streptococcal bacteraemia. Whether a procedure necessitates prophylaxis depends on these factors.

Signs and symptoms:

1.       Fever: low grade and intermittent 90% of IE patients

2.       Heart murmurs 85% of IE patients

3.       Other symptoms up to 50% of IE patients

a.       Petichiae

b.      Splinter haemorrhage (in nail beds)

c.       Osler nodes (tender subcutaneous nodules usually found on the distal finger pads)

d.      Janeway lesions: non tender discolouration on the palms and soles

e.      Roth spots: Retinal hemorrhages with small, clear centres, rare.

4.       Neurologic symptoms (Up to 40% of IE patients):

a.       Embolic stroke

b.      Intracerebral haemorrhage

c.       Microabscesses

5.       Other

a.       Splenomegaly

b.     Stiff neck

c.     Delirium

d.     Paralysis, hemiparesis, aphasia

e.     Conjunctival hemorrhage

f.      Pallor

g.     Gallops

h.     Rales

i.      Cardiac arrhythmia

j.      Pericardial rub

k.     Pleural friction rub

Treatment of IE:

Antibiotics are the mainstay of treatment. 3-5 sets of blood cultures within 60-90 minutes.

Initial empiric dose then appropriate antibiotic regimen

Dental guidelines

Infective endocarditis is more likely to result from bacteraemia associated with daily activities than from specific dental procedures, so the maintenance of good oral health and hygiene is more important than periprocedural antibiotics.

All patients with cardiac abnormalities should be reminded to practise good oral hygiene and have regular dental check-ups, with preventive dental and periodontal treatment to ensure optimal oral health. In particular, dental examination is recommended twice yearly for patients with a cardiac condition involving the endocardium, especially those listed in Box 2.4. Doctors should investigate an unexplained fever because it could be a sign of endocarditis, and take samples for blood cultures before administering any oral or IV antibiotics.

No randomised controlled trial has been performed to determine the role of antibiotic prophylaxis, and there are no human studies showing that it can prevent endocarditis. Therapeutic Guidelines: Antibiotic continues to recommend antibiotic prophylaxis in a restricted group of patients until further evidence is available.

Self-performed oral hygiene, such as toothbrushing, flossing or use of oral irrigators, can produce a similar incidence of bacteraemia to that caused by most dental procedures (excluding extractions). As these activities are performed more frequently than dental procedures, they have the potential to produce regular episodes of bacteraemia, particularly in patients with gingival inflammation. The cumulative effect of repeated episodes of bacteraemia caused by self-performed oral hygiene is very likely to be a more important risk factor for infective endocarditis than isolated episodes of bacteraemia occurring during dental visits, especially in patients with poor oral health and hygiene. However, dental procedures are generally of longer duration than self-performed oral hygiene, and so expose patients to a longer duration of bacteraemia. Antibiotic prophylaxis is therefore warranted for some dental procedures in high-risk patients.

In making the decision about whether to administer antibiotic prophylaxis before a procedure in a particular patient, the following risks must be considered:

1.       the risk of giving the antibiotic

2.       the risk of the patient developing endocarditis from the procedure

3.       the risk of a potential adverse outcome if the patient does develop endocarditis

Antibiotic prophylaxis is recommended only for patients with a cardiac condition associated with the highest risk of adverse outcomes from endocarditis (seeBox 2.4) who are undergoing certain dental procedures (see Table 2.2) or other procedures (see Table 2.3 and Table 2.4). This list of cardiac conditions is short; all of these patients have had significant cardiovascular diseases or interventions. Prophylaxis is also recommended for high-risk patients with documented rheumatic heart disease (see below). Prophylaxis is not recommended for patients with other forms of valvular or structural heart disease, including mitral valve prolapse.

Antibiotic prophylaxis is recommended in patients with the following cardiac conditions who are undergoing certain dental procedures (see Table 2.2) or other procedures (see Table 2.3 and Table 2.4) [NB1]:

prosthetic cardiac valve or prosthetic material used for cardiac valve repair

o   Previous infective endocarditis

o   Congenital heart disease but only if it involves:

o   Unrepaired cyanotic defects, including palliative shunts and conduits

o   Completely repaired defects with prosthetic material or devices, whether placed by surgery or catheter intervention, during the first 6 months after the procedure (after which the prosthetic material is likely to have been endothelialised)

o   Repaired defects with residual defects at or adjacent to the site of a prosthetic patch or device (which inhibit endothelialisation)

o   Patients who have had a heart transplant may also be at high risk of adverse outcomes from endocarditis; consult the patient's cardiologist for specific recommendations.

o   Rheumatic heart disease in high-risk patients: Antibiotic prophylaxis should be administered to all Indigenous Australians with rheumatic heart disease who are undergoing certain dental procedures (see Table 2.2) or other procedures (see Table 2.3 and Table 2.4). Non-Indigenous patients with rheumatic heart disease and who are at significant socioeconomic disadvantage should also be considered for antibiotic prophylaxis.

o   Antibiotic prophylaxis is no longer indicated in patients with aortic stenosis, mitral stenosis, or symptomatic or asymptomatic mitral valve prolapse.

Dental procedures and their requirement for endocarditis prophylaxis in patients with a cardiac condition listed in Table 2.2

Prophylaxis always required	Prophylaxis required in some circumstances	Prophylaxis not required
extraction periodontal procedures including surgery, subgingival scaling and root planing replanting avulsed teeth other surgical procedures (eg apicoectomy)	Consider prophylaxis for the following procedures if multiple procedures are being conducted, the procedure is prolonged or periodontal disease is present: full periodontal probing for patients with periodontitis intraligamentary and intraosseous local anaesthetic injection supragingival calculus removal/cleaning rubber dam placement with clamps (where there is a risk of damaging gingiva) restorative matrix band/strip placement endodontics beyond the apical foramen placement of orthodontic bands placement of interdental wedges subgingival placement of retraction cords, antibiotic fibres or antibiotic strips	oral examination infiltration and block local anaesthetic injection restorative dentistry supragingival rubber dam clamping and placement of rubber dam intracanal endodontic procedures removal of sutures impressions and construction of dentures orthodontic bracket placement and adjustment of fixed appliances application of gels intraoral radiographs supragingival plaque removal

If, after careful evaluation of both the cardiac condition (see Box 2.4) and the dental procedure (see Table 2.2), antibiotic prophylaxis is considered necessary, a single dose of antibiotic should be given before the procedure. There is no proven value to giving a dose after the procedure.

If a patient is having more than one procedure requiring antibiotic prophylaxis, dentists should plan treatment so that all of the procedures can be completed in a single or at most two sittings, if possible, thus avoiding the need for multiple antibiotic doses.

For standard prophylaxis, use:

Amoxicillin 2g (50mg/kg up to 2g)

Orally 1hr before the procedure

Amoxy/ampicillin

IV within 60 mins of the procedure (ideally 15-30 mins before)

IM 30 mins before the procedure

Penicillin hypersensitivity (except immediate hypersensitivity)

Cephalexin 2g (50mg up to 2g)

Orally 1hr before procedure

Cephazolin 2g (30mg/kg up to 2g) IV

<60 mins before (ideally 15-30 mins)

IM 30 mins before procedure

Immediate penicillin hypersensitivity

Clindamycin 600mg (20mg.kg up to 600mg)

Orally 1 hour before the procedure

IV over at least 20 mins (<60 mins before the procedure ideally 15-30 mins)

In patients currently taking or who have recently taken a course of beta-lactam therapy, evidence suggests that the amoxycillin susceptibility of viridans streptococci may be affected. Therefore, a non–beta-lactam antibiotic, such as clindamycin, may be considered for prophylaxis in this setting.

Note 1: For patients unable to swallow clindamycin capsules, a 50 mg/mL oral solution can be made before each dose by dissolving the contents of one 150 mg capsule in 2 mL of water. Draw this solution into a syringe and make the volume up to 3 mL (if necessary). The required volume of solution should be mixed with juice or soft food before administration to disguise the taste.

Note 2: Lincomycin is used instead of IV clindamycin in some centres. The recommended dose of lincomycin is 600 mg (child: 20 mg/kg up to 600 mg) IV over at least 1 hour.