Infective endocarditis — structured written assessment

SAQ 1 (10 marks)

A 64-year-old man with a bioprosthetic aortic valve implanted 5 years ago has 10 days of fever and malaise. Two of two blood culture sets grow methicillin-susceptible Staphylococcus aureus. Transthoracic echocardiography (TTE) shows a well-seated prosthesis and no vegetation. He is haemodynamically stable.

• (a) Outline the imaging strategy recommended by the 2023 ESC guideline. (4 marks)^[1]
• (b) Give the 2023 ESC antibiotic regimen, with adult doses, and say when rifampin starts. (3 marks)^[1]
• (c) List the 2023 ESC surgical indications that could apply to him, with their timing. (3 marks)^[1]

Model answers

(a) Imaging (4 marks)

• Transoesophageal echocardiography (TOE) is recommended in suspected infective endocarditis (IE) when a prosthetic valve or an intracardiac device is present (Class I, Level B), and in all patients with suspected IE and a negative or non-diagnostic TTE (Class I, Level B).^[1]
• Echocardiography should be considered in S. aureus, E. faecalis and some Streptococcus spp. bacteraemia (Class IIa, Level B).^[1]
• If the first studies are negative or inconclusive and suspicion stays high, repeat TTE and/or TOE within 5–7 days (Class I, Level C).^[1]
• In possible prosthetic valve endocarditis (PVE), [18F]FDG-PET/CT(A) and cardiac computed tomography angiography (CTA) are recommended to detect valvular lesions and confirm IE (Class I, Level B).^[1] Abnormal prosthetic or periprosthetic uptake (intense focal or heterogeneous) on [18F]FDG-PET/CT or white blood cell (WBC) SPECT/CT should be considered a major criterion for PVE, irrespective of the interval from surgery.^[1]
• Cardiac CTA is recommended in PVE to diagnose periprosthetic complications if echocardiography is inconclusive (Class I, Level B).^[1]
• WBC SPECT/CT should be considered with high suspicion of PVE when echocardiography is negative or inconclusive and PET/CT is unavailable (Class IIa, Level C).^[1]
• Brain and whole-body imaging are recommended if he has symptoms suggesting septic embolic complications, to detect peripheral lesions or add minor diagnostic criteria (Class I, Level B).^[1]
• If he has no such symptoms, brain and whole-body imaging may be considered to screen for peripheral lesions (Class IIb, Level B).^[1]

(b) Antibiotics (3 marks)

• For PVE due to methicillin-susceptible staphylococci (which include his methicillin-susceptible Staphylococcus aureus): (flu)cloxacillin or cefazolin with rifampin for at least 6 weeks, and gentamicin for 2 weeks (Class I, Level B); cloxacillin is not recommended if the patient has penicillin allergy.^[1]
• Adult doses: (flu)cloxacillin 12 g/day intravenous (i.v.) in 4–6 doses or cefazolin 6 g/day i.v. in 3 doses; rifampin 900 mg/day i.v. or orally in 3 equally divided doses; gentamicin 3 mg/kg/day i.v. or intramuscular (i.m.) in 1 (preferred) or 2 doses.^[1]
• Start rifampin after 3–5 days of effective therapy, once the bacteraemia has cleared.^[1]
• Gentamicin: maximum 240 mg/day; monitor renal function and gentamicin levels weekly; once-daily trough below 1 mg/L.^[1]
• Count the duration from the first day of effective therapy (a negative blood culture if cultures were initially positive), not from the day of surgery.^[1]
• After at least 10 days of appropriate i.v. treatment (or at least 7 days after cardiac surgery), if clinically stable and TOE shows no abscess or valve abnormality requiring surgery, outpatient parenteral or oral treatment should be considered for left-sided S. aureus IE (Class IIa, Level A); TOE is recommended when stable, before any switch to oral treatment (Class I, Level B).^[1]

(c) Surgery (3 marks)

• Urgent surgery (within 3–5 days) should be considered in PVE caused by S. aureus or non-HACEK Gram-negative bacteria (Class IIa, Level C).^[1]
• In aortic or mitral native valve endocarditis (NVE) or PVE, emergency surgery (within 24 h) is recommended for severe acute regurgitation, obstruction or fistula causing refractory pulmonary oedema or cardiogenic shock; urgent surgery for severe acute regurgitation or obstruction causing heart failure (HF) symptoms or echocardiographic signs of poor haemodynamic tolerance (both Class I, Level B).^[1]
• In left-sided NVE or PVE, urgent surgery is recommended for locally uncontrolled infection: abscess, false aneurysm, fistula, enlarging vegetation, prosthetic dehiscence or new atrioventricular block (AVB) (Class I, Level B).^[1]
• Urgent surgery should be considered for blood cultures persistently positive for more than 1 week, or persistent sepsis, despite appropriate antibiotics and control of metastatic foci (Class IIa, Level B).^[1]
• If surgery is needed, intra-operative echocardiography is recommended (Class I, Level C).^[1]
• Urgent surgery is recommended in aortic or mitral NVE or PVE with a persistent vegetation of at least 10 mm after one or more embolic episodes despite appropriate antibiotics (Class I, Level B).^[1]
• Urgent surgery is recommended for a vegetation of at least 10 mm with another indication for surgery (Class I, Level C).^[1]
• Urgent surgery may be considered for an aortic or mitral vegetation of at least 10 mm without severe valve dysfunction or without clinical evidence of embolism, if surgical risk is low (Class IIb, Level B).^[1]

SAQ 2 (10 marks)

A 70-year-old woman who had transcatheter aortic valve implantation 2 years ago needs a dental extraction. She reports a rash with amoxicillin in the past, without anaphylaxis, angioedema or urticaria.

• (a) Is antibiotic prophylaxis indicated? Give the 2023 ESC recommendation. (2 marks)^[1]
• (b) Choose a regimen for her. (3 marks)^[1]
• (c) Name three other patient groups for whom ESC 2023 recommends prophylaxis, and two in whom it is weaker, with class. (3 marks)^[1]
• (d) List the general prevention measures she should follow. (2 marks)^[1]

Model answers

(a) Indication (2 marks)

• Yes. Prophylaxis is recommended in patients with transcatheter aortic and pulmonary valve prostheses (Class I, Level C).^[1]
• In high-risk patients, antibiotic prophylaxis is recommended for dental extractions, oral surgery and procedures manipulating the gingival or periapical region of the teeth (Class I, Level B).^[1]

(b) Regimen (3 marks)

• She has a penicillin allergy without anaphylaxis, angioedema or urticaria, so a cephalosporin can be used.^[1]
• Cephalexin 2 g orally (or another first- or second-generation oral cephalosporin in equivalent adult dosing), as a single dose 30–60 min before the procedure.^[1]
• Alternatives in penicillin allergy: azithromycin or clarithromycin 500 mg orally, doxycycline 100 mg orally, or cefazolin or ceftriaxone 1 g i.m. or i.v.^[1]
• Clindamycin is not recommended, because its risk of adverse events appears high, mainly Clostridioides difficile infection.^[1]

(c) Other groups (3 marks)

• Class I: previous IE (Level B); surgically implanted prosthetic valves or any material used for surgical valve repair (Level C); untreated cyanotic congenital heart disease (CHD) and CHD treated with post-operative palliative shunts, conduits or other prostheses, but after surgical repair without residual defects or valve prostheses only for the first 6 months (Level C); ventricular assist devices (Level C).^[1]
• Class IIa, Level C: transcatheter mitral and tricuspid valve repair.^[1]
• Class IIb, Level C: heart transplant recipients.^[1]

(d) General measures (2 marks)

• General prevention measures are recommended in individuals at high and intermediate risk (Class I, Level C).^[1]
• Twice-daily tooth cleaning, with professional dental cleaning and follow-up at least twice yearly for high-risk patients.^[1]
• Strict skin hygiene and wound disinfection, curative antibiotics for bacterial infection, no self-medication with antibiotics, and discouraging piercing and tattooing.^[1]
• Strict infection control for any at-risk procedure, and limiting infusion catheters and invasive procedures when possible, with strict adherence to care bundles for cannulae.^[1]
• Report that she is at risk when she has unexplained fever, so that IE screening is considered before antibiotics start.^[1]