Prevention of infective endocarditis

Preventing infective endocarditis

Antibiotic prophylaxis aims to reduce the incidence of infective endocarditis (IE).¹ Measures to prevent IE need to go beyond antibiotic prophylaxis and the risks of antibiotic prophylaxis need to be considered. Therefore, antibacterial prophylaxis is not routinely recommended for the prevention of infective endocarditis in patients undergoing the following procedures:²

• Dental.

• Upper and lower respiratory tract (including ear, nose, and throat procedures and bronchoscopy).

• Genito-urinary tract (including urological, gynaecological, and obstetric procedures).

• Upper and lower gastro-intestinal tract.

The scope and importance of antibiotic prophylaxis³

Although IE is a rare condition, it is often difficult to diagnose and associated with high morbidity and mortality. With an ageing population and increasing use of implantable cardiac devices and heart valves, the epidemiology of IE has changed. Early clinical suspicion and a rapid diagnosis are essential to enable the correct treatment pathways to be accessed and to reduce complication and mortality rates.⁴

See also the article on Infective Endocarditis.

Antibiotic prophylaxis for IE has traditionally been thought to work at one of three steps in the pathogenic process:

• Killing the pathogen in the bloodstream before it can adhere to the heart valve.

• Preventing adherence of bacteria to the thrombus forming on the valve.

• Eradicating organisms that do attach to the thrombus.

However, the level of evidence of antibiotic prophylaxis efficiency is low and the indications of its prescription have been restricted in recent guidelines.^{5 6}

• Guidelines for use of antibiotic prophylaxis of IE have been developed often with international consensus. It should be remembered that:
  

  • They are unproven by randomised controlled trials.¹

  • Even when guidelines are followed appropriately, they may fail to prevent IE. The guidelines exist to guide and inform but may occasionally be modified to fit particular circumstances.

  • Guidelines by the British Society for Antimicrobial Chemotherapy and by the American Heart Association have highlighted the prevalence of bacteraemia that arise from everyday activities such as toothbrushing, the lack of association between episodes of IE and prior interventional procedures, and the lack of efficacy of antibiotic prophylaxis regimens.⁷

• The scope for prevention is limited:
  

  • Only 15-20% of cases of IE result from the bacteraemia produced by an invasive procedure.

  • Only half of patients developing IE after invasive procedures were identified beforehand as candidates for antibiotic prophylaxis.

  • This means that only 10% of all cases of IE can be prevented by prophylactic antibiotics.

National Institute for Health and Care Excellence (NICE) guidance³

Prophylaxis for dental procedures

There is no evidence to support the use of antibiotics to prevent endocarditis in dental procedures.¹ The use of chlorhexidine mouthwashes is also no longer recommended.

Endocarditis prophylaxis for non-dental procedures

Routine prophylaxis is now no longer recommended and antibiotics would only be given to treat active infection (of whatever type) whilst awaiting (or with) microbiological advice.

Any infection in patients at risk of endocarditis should be investigated promptly and treated appropriately to reduce the risk of endocarditis.

If patients at risk of endocarditis are undergoing a gastro-intestinal or genito-urinary tract procedure at a site where infection is suspected, they should receive appropriate antibacterial therapy that includes cover against organisms that cause infective endocarditis.

Patients at risk of infective endocarditis should be:

• Advised to maintain good oral hygiene.

• Told how to recognise signs of infective endocarditis, and advised when to seek expert advice.

What other preventative measures can be taken?³

Good oral hygiene is very important and good dental care should be facilitated. Patients with a cardiac anomaly putting them at risk of endocarditis (high-risk and moderate-risk patients above) should be referred for dental assessment. Any interventions should be performed at least 14 days before cardiac surgery, in order to allow mucosal healing. If cardiac surgery is performed as an emergency before dental assessment can be made, the assessment should be made at the earliest opportunity after surgery. Elective dental procedures should be delayed for three months post-surgery.

General measures and health education have enormous potential to prevent IE - for example:

• Education of patients to inform doctors and healthcare workers of any underlying diagnosis/IE risk.

• Since gingivitis is the most common cause of spontaneous bacteraemia, meticulous oral hygiene is important. Similarly, attention to skin hygiene is important in prevention.

• Many cases of hospital-acquired infection can be prevented by better asepsis during handling and insertion of vascular catheters and prompt removal if infected. Poor hospital hygiene has been blamed for the rise in meticillin-resistant Staphylococcus aureus (MRSA).

• Needle-exchange programmes, education and addiction treatment for drug-abusers.