MBBS OSCE · Cardiology / General Medicine

OSCE — assessment and management of suspected infective endocarditis

An 8-minute OSCE station assessing the candidate's structured assessment of a patient with suspected infective endocarditis — recognising the fever-murmur-stigmata cluster, applying the Duke criteria, ordering the key investigations (blood cultures, echo), choosing empiric and targeted bactericidal therapy with drug/dose/route, and stating the three ESC indications for early surgery. Marks for the diagnostic criteria, the antibiotic strategy and the surgical triggers.

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NEET-PGINICET

Brief (to candidate)

A 47-year-old man with a known bicuspid aortic valve presents with three weeks of fever, night sweats and 5 kg weight loss. On examination his temperature is 38.5 degrees C, he has a new early diastolic murmur at the left sternal edge, splinter haemorrhages, and tender nodules on the pads of two fingers. Three sets of blood cultures (drawn before antibiotics) grow viridans streptococci. An echocardiogram shows an 8 mm mobile aortic-valve vegetation with mild aortic regurgitation. You have 8 minutes to assess him, apply the Duke criteria, state the key investigations, outline your definitive antibiotic strategy (drug, dose, route, duration), and state the indications for early surgery and whether he currently meets them.

Candidate instructions

  1. Take a focused history (fever, constitutional symptoms, embolic events, predisposition, portal of bacteraemia such as dental work or IV drug use) and examine for the peripheral stigmata.
  2. Apply the modified Duke criteria and classify the case (definite, possible, rejected).
  3. State the key investigations and why cultures must be drawn before antibiotics.
  4. Outline the definitive antibiotic strategy for penicillin-susceptible viridans streptococci (drug, dose, route, duration), and the principle behind it.
  5. State the three ESC indications for early surgery and decide whether this patient currently meets any.

Examiner checklist (mark each domain / 10)

DomainKey actions expected
History / clusterElicits fever + new murmur + stigmata; recognises the predisposing bicuspid valve; asks about embolic events and the portal (dental hygiene/procedures)
StigmataIdentifies splinter haemorrhages and Osler nodes (tender, immune-complex, pulps — a minor criterion); distinguishes Osler from Janeway (painless, septic emboli, palms/soles)[5]
Duke criteriaNames the two MAJOR criteria (typical positive blood culture; echo vegetation/new regurgitation) and classifies as definite IE; lists the minor criteria (predisposition, fever, vascular, immunologic, microbiology)[5]
InvestigationsThree sets of blood cultures from separate sites before antibiotics; TTE then TOE if negative/prosthetic/suspected abscess; bloods (CRP, renal), ECG for PR prolongation (aortic-root abscess)[3]
Antibiotic strategyBenzylpenicillin 1.2 g IV 4-hourly OR ceftriaxone 2 g IV daily for 4 weeks (bactericidal, high-dose, IV, prolonged because the avascular vegetation shelters organisms); gentamicin for 2-week synergy in selected cases[3]
Surgical indicationsThe three ESC indications — heart failure (commonest), uncontrolled infection (abscess/new heart block), prevention of embolism (>10 mm mobile vegetation/emboli); states the 8 mm vegetation does NOT yet meet the >10 mm threshold[1]
Safety-netWatch for heart failure, emboli, new conduction block; repeat echo and inflammatory markers; dental clearance; prophylaxis counselling

Model key actions

  • Diagnose: definite IE — two major criteria (typical blood culture + echo vegetation/new regurgitation).[5]
  • Investigate: cultures already drawn (correct, before antibiotics); TTE shown — would progress to TOE if prosthetic or if abscess suspected; send CRP, renal function, urine, ECG.[3]
  • Treat: benzylpenicillin 1.2 g IV 4-hourly or ceftriaxone 2 g IV daily for 4 weeks; monitor CRP, renal function and repeat echo.[3]
  • Surgical decision: 8 mm mobile vegetation without embolism or dysfunction does NOT yet meet the > 10 mm threshold; continue medical therapy with surveillance for heart failure, emboli and PR prolongation (aortic-root abscess = surgical emergency).[1]

Common errors

  • Not applying the Duke criteria explicitly — naming "endocarditis" without the two major criteria that make it definite.
  • Drawing too few cultures, or after antibiotics — three sets from separate sites before antibiotics is the cornerstone.
  • Recommending oral or short-course therapy — must be bactericidal, high-dose, IV, 4-6 weeks.
  • Quoting the wrong commonest surgical indication — heart failure, not emboli.
  • Operating on a sub-threshold vegetation — an 8 mm vegetation without embolism or dysfunction does not meet the > 10 mm criterion; over-callling surgery is an error as much as missing it.
  • Missing perivalvular extension — not checking the ECG for a new PR prolongation (aortic-root abscess).
References3Show
  1. [3]Baddour LM, Wilson WR, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications (AHA Scientific Statement). Circulation, 2015.PMID 26373316
  2. [5]Li JS, Sexton DJ, et al. Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Clinical Infectious Diseases, 2000.PMID 10770721
  3. [1]Delgado V, Ajmone Marsan N, et al. 2023 ESC Guidelines for the management of endocarditis. European Heart Journal, 2023.PMID 37622656
OSCE — assessment and management of suspected infective endocarditis · MBBS OSCE · NeetVellum