4.5 Infective Endocarditis & Cardiovascular Infection

ABIM Internal Medicine Exam

Track your progress as you read

Finished sections get a check mark.

1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy

0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan

2 Chapter 1: Cardiovascular Disease (14% of Exam)

1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection

3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)

2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia

4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)

3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV

5 Chapter 4: Infectious Disease (9% of Exam)

4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections

6 Chapter 5: Pulmonary Disease (9% of Exam)

5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule

7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)

6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease

8 Chapter 7: Hematology (6% of Exam)

7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation

9 Chapter 8: Medical Oncology (6% of Exam)

8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care

10 Chapter 9: Nephrology & Urology (6% of Exam)

9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria

11 Chapter 10: Neurology (4% of Exam)

10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders

12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)

11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health

13 Chapter 12: Dermatology (3% of Exam)

12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease

14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)

13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications

15 Chapter 14: Geriatric Syndromes (3% of Exam)

14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings

16 Chapter 15: Allergy & Immunology (2% of Exam)

15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders

17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology

16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design

18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)

17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity

19 Chapter 18: Perioperative Medicine & Medical Consultation

18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications

20 Chapter 19: Ophthalmology (1% of Exam)

19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease

21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)

20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders

4.5 Infective Endocarditis & Cardiovascular Infection

Key Takeaways Explain This Topic AI

Endocarditis, infections of the pericardial space, endocarditis prophylaxis, suppurative thrombophlebitis, catheter-related infections and device or pocket infections are the enumerated topics.

Three sets of blood cultures from separate sites should be obtained before antibiotics in suspected endocarditis whenever the patient is stable.

Streptococcus gallolyticus bacteremia mandates colonoscopy because of its association with colorectal neoplasia.

Surgical indications include heart failure from valvular destruction, uncontrolled infection or abscess, and recurrent embolization with a large persistent vegetation.

Transesophageal echocardiography is required when transthoracic imaging is non-diagnostic, and always for prosthetic valves and intracardiac devices.

Last updated: August 2026

Infective endocarditis and healthcare-associated infections like Clostridioides difficile colitis and central venous catheter bloodstream infections represent high-stakes clinical scenarios requiring strict adherence to evidence-based diagnostic criteria and surgical timing.

1. Infective Endocarditis (IE)

Infective endocarditis is an infection of the endocardial surface of the heart, most commonly affecting native or prosthetic cardiac valves or implanted intracardiac devices.

Pathophysiology & Microbiology

Endothelial Injury: Turbulent blood flow (valvular stenosis/regurgitation, congenital defects) damages endothelium, exposing subendothelial collagen and tissue factor, triggering platelet and fibrin deposition to create a sterile non-bacterial thrombotic endocarditis (NBTE) nidus.

Bacteremic Seeding: Transient bacteremia leads to microbial adhesion to the sterile vegetation, followed by bacterial proliferation and biofilm formation.

Pathogen Clinical Context & High-Yield Associations Key Characteristics

Staphylococcus aureus • Most common overall cause of acute native valve IE and IV drug use (IVDA) IE; • Affects normal and damaged valves; high rate of embolization and rapid destruction • IVDA classically involves the tricuspid valve (presents with septic pulmonary emboli, cavitary lung nodules, triad of fever, hemoptysis, and pleuritic pain).

Viridans Group Streptococci ( S. sanguinis, S. mitis, S. mutans, S. salivarius ) • Subacute native valve IE; • Arises from oral cavity / dental flora following dental procedures • Highly sensitive to penicillin; typically involves previously damaged or diseased valves.

Enterococcus faecalis / faecium • Older men following genitourinary procedures , urinary tract infections, or GI manipulation • Inherently resistant to many cephalosporins; treated with Ampicillin + Ceftriaxone or Ampicillin + Gentamicin.

Streptococcus gallolyticus ( formerly S. bovis ) • Strong, direct association with occult colonic neoplasia (adenomatous polyps or adenocarcinoma) or inflammatory bowel disease • Mandatory Clinical Pearl: Diagnosis of S. gallolyticus bacteremia or IE mandates a complete colonoscopy .

Coagulase-Negative Staphylococci ( S. epidermidis ) • Most common cause of Prosthetic Valve Endocarditis (PVE) within the first 12 months of valve replacement surgery • Biofilm producer on prosthetic materials; requires combination therapy including Rifampin .

HACEK Group ( Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella ) • Fastidious Gram-negative bacilli of oral cavity; subacute IE course with large vegetations • Blood culture-negative or slow growth (>5 days); sensitive to Ceftriaxone.

Culture-Negative IE Organisms • Coxiella burnetii (Q fever - livestock contact; elevated Phase I IgG titers >1:800); • Bartonella henselae / quintana (cat scratch, body lice; serology/PCR); • Tropheryma whipplei , Brucella , Legionella • Requires specialized serological testing, lysis-centrifugation blood cultures, or valve tissue PCR.

Loading diagram... Modified Duke Criteria & Surgical Indications Decision Tree

The Modified Duke Criteria for Diagnosis

Definitive diagnosis requires: 2 Major Criteria , OR 1 Major + 3 Minor Criteria , OR 5 Minor Criteria .

A. Major Criteria

Positive Blood Cultures for Infective Endocarditis:

Typical microorganisms consistent with IE from 2 separate blood cultures : Viridans streptococci , Streptococcus gallolyticus , HACEK group, Staphylococcus aureus , or community-acquired Enterococci in the absence of a primary focus; OR

Microorganisms consistent with IE from persistently positive blood cultures : blood cultures drawn >12 hours apart, or all of 3, or majority of >=4 separate cultures (with first and last drawn >=1 hour apart); OR

Single positive blood culture for Coxiella burnetii or antiphase I IgG antibody titer >1:800.

Evidence of Endocardial Involvement:

Positive Echocardiogram: Oscillating intracardiac mass/vegetation on valve or supporting structures, perivalvular abscess, or new partial dehiscence of a prosthetic valve; OR

New Valvular Regurgitation (worsening or changing of pre-existing murmur not sufficient).

B. Minor Criteria

Predisposition: Predisposing heart condition (prosthetic valve, prior IE, rheumatic valve disease, congenital heart defect) or injection drug use.

Fever: Temperature >= 38.0°C (100.4°F).

Vascular Phenomena: Major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, or Janeway lesions (painless, flat, erythematous/hemorrhagic macules on palms and soles caused by septic microemboli).

Immunologic Phenomena: Glomerulonephritis, Osler nodes (painful, violaceous, tender subcutaneous nodules on the pulp of fingers and toes caused by immune complex deposition), Roth spots (retinal hemorrhages with pale/white fibrin centers), or positive Rheumatoid Factor (RF).

Microbiological Evidence: Positive blood culture not meeting a major criterion or serological evidence of active infection with an organism consistent with IE.

Antimicrobial Therapy for Endocarditis

Empiric Regimen for Native Valve IE: Vancomycin (15–20 mg/kg IV q8–12h targeting trough 15–20 mcg/mL) PLUS Ceftriaxone (2 g IV daily) OR Ampicillin-sulbactam (3 g IV q6h).

Empiric Regimen for Prosthetic Valve IE (PVE): Vancomycin (15–20 mg/kg IV q8–12h) PLUS Cefepime (2 g IV q8h) or Gentamicin (1 mg/kg IV q8h) PLUS Rifampin (300 mg PO/IV q8h).

Rifampin Clinical Pearl: Rifampin penetrates staphylococcal biofilms on prosthetic materials; it should ideally be added 2–3 days after initiating vancomycin once bacteremia has cleared to prevent emergence of rifampin resistance.

Treatment Duration: Minimum 4 to 6 weeks of targeted IV bactericidal therapy calculated from the date of the first negative blood culture.

Indications for Urgent Cardiac Surgery (Class I)

Acute Valvular Dysfunction Causing Heart Failure: Severe acute aortic or mitral regurgitation or valve obstruction resulting in cardiogenic shock or refractory pulmonary edema .

Uncontrolled Infection / Persistent Bacteremia: Persistent positive blood cultures or unrelenting fever >5 to 7 days after initiation of appropriate targeted antimicrobial therapy.

Locally Invasive Infection / Extension: Development of perivalvular abscess (aortic root abscess), pseudoaneurysm, fistula , or new cardiac conduction abnormalities (e.g., new 1st-degree AV block or bundle branch block , which indicates extension of an aortic root abscess into the AV node and bundle of His).

Fungal Endocarditis: Endocarditis caused by Candida spp. or Aspergillus spp. (medical therapy alone is uniformly fatal).

Prevention of Embolism: Recurrent embolic events or large mobile vegetations (>10 mm in diameter) despite appropriate antimicrobial therapy, especially on anterior mitral valve leaflets.

Infective Endocarditis Prophylaxis Guidelines

Antimicrobial prophylaxis is recommended ONLY for high-risk cardiac conditions undergoing high-risk dental procedures involving manipulation of gingival tissue, periapical region of teeth, or perforation of oral mucosa .

High-Risk Cardiac Conditions:

Prosthetic cardiac valves or prosthetic material used for cardiac valve repair.

Previous history of infective endocarditis.

Unrepaired cyanotic congenital heart disease (CHD), or repaired CHD with residual shunts or prosthetic material.

Cardiac transplant recipients who develop cardiac valvulopathy.

Recommended Prophylaxis Regimen: Oral Amoxicillin 2 g administered as a single dose 30 to 60 minutes prior to the procedure (if penicillin-allergic without history of anaphylaxis: Cephalexin 2 g, or Azithromycin/Clarithromycin 500 mg, or Doxycycline 100 mg).