Study guide
4.8 Opportunistic Infections & Sexually Transmitted Infections
ABIM Internal Medicine Exam
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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
4.8 Opportunistic Infections & Sexually Transmitted Infections
Key Takeaways Explain This Topic AI
Urethritis, genital ulcers, vulvovaginitis, cervicitis, epididymitis, syphilis and human papillomavirus are enumerated under sexually transmitted diseases.
Prophylaxis against Pneumocystis begins below a CD4 count of 200 cells per microliter and against Mycobacterium avium complex historically below 50.
Adjunctive corticosteroids are indicated in Pneumocystis pneumonia when the arterial oxygen tension is below 70 mmHg or the alveolar-arterial gradient exceeds 35 mmHg.
Neurosyphilis is treated with intravenous penicillin G rather than intramuscular benzathine penicillin, and penicillin-allergic patients require desensitization.
Immune reconstitution inflammatory syndrome is an enumerated blueprint topic and represents paradoxical worsening after antiretroviral initiation rather than treatment failure.
Last updated: August 2026
- 1. Opportunistic Infections (OIs) Stratified by CD4 Count
- A. CD4 < 200 cells/mcL (or CD4% < 14%)
- Pneumocystis jirovecii Pneumonia (PJP / PCP)
Clinical Presentation: Subacute onset (over 2–4 weeks) of progressive exertional dyspnea, non-productive dry cough, low-grade fever, hypoxemia, and markedly elevated serum Lactate Dehydrogenase (LDH >500 IU/L) . Chest radiography/CT shows bilateral diffuse, symmetric interstitial/perihilar ground-glass opacities.
Primary Prophylaxis: Indicated when CD4 < 200 cells/mcL or history of oral candidiasis (thrush). First-line: Trimethoprim-sulfamethoxazole (TMP-SMX) 1 Double-Strength (DS) tab PO daily (or 1 Single-Strength tab daily). Alternatives for severe sulfa allergy: Dapsone (100 mg daily; check G6PD first), Atovaquone (1500 mg daily), or monthly aerosolized Pentamidine (300 mg). Discontinue when CD4 >200 cells/mcL for >=3 months on ART.
Acute Treatment: High-dose TMP-SMX (15–20 mg/kg/day of TMP component IV or PO divided q6–8h for 21 days) .
Mandatory Adjunctive Corticosteroids: Initiate IV/PO Prednisone (40 mg BID x 5 days, 40 mg daily x 5 days, then 20 mg daily x 11 days) before or concurrently with antimicrobial therapy IF:
Room air arterial PaO2 < 70 mmHg , OR
Alveolar-Arterial (A-a) oxygen gradient >= 35 mmHg .
Mechanism: Prevents severe inflammatory lung injury and respiratory failure triggered by dying Pneumocystis organisms.
- B. CD4 < 100 cells/mcL
- Toxoplasma gondii Encephalitis
Clinical Presentation: Subacute headache, confusion, focal neurological deficits (hemiparesis, cranial nerve palsies), and seizures. MRI brain reveals multiple ring-enhancing lesions with surrounding vasogenic edema , with a predilection for the basal ganglia and gray-white junction.
Primary Prophylaxis: TMP-SMX 1 DS tab daily in patients who are Toxoplasma IgG seropositive with CD4 < 100 cells/mcL (standard PJP prophylaxis provides dual coverage).
Acute Treatment: Pyrimethamine + Sulfadiazine + Leucovorin (folinic acid) for 6 weeks. (Leucovorin is mandatory to prevent pyrimethamine-induced bone marrow suppression). Alternative: Pyrimethamine + Clindamycin + Leucovorin.
Cryptococcal Meningitis ( Cryptococcus neoformans )
Clinical Presentation: Subacute indolent headache, fever, malaise, cranial neuropathies (CN VI diplopia), and elevated intracranial pressure (papilledema, lethargy).
Diagnostics: Lumbar puncture demonstrates elevated opening pressure (>200 mm H2O in >75% of cases) , positive CSF Cryptococcal Antigen (CrAg) titer (>98% sensitivity/specificity), positive India ink stain (encapsulated budding yeasts), and lymphocytic pleocytosis with low glucose.
Three-Phase Management Strategy:
Induction Phase (Minimum 2 weeks): Liposomal Amphotericin B (3–4 mg/kg IV daily) PLUS Flucytosine (100 mg/kg/day PO divided q6h) until clinical improvement and documented CSF fungal clearance.
Consolidation Phase (Minimum 8 weeks): High-dose Fluconazole (400–800 mg PO daily) .
Maintenance Phase: Fluconazole (200 mg PO daily) for at least 1 year (discontinue once CD4 >100 for >=3 months on ART with undetectable viral load).
Intracranial Pressure (ICP) Control: Perform serial daily therapeutic lumbar punctures to remove CSF and maintain opening pressure <200 mm H2O (or reduce by 50% if opening pressure >400 mm H2O). Lumbar drains or VP shunts are indicated for refractory intracranial hypertension. (Steroids, mannitol, and acetazolamide are contraindicated).
Timing of ART Initiation: Delay ART for 2 to 6 weeks after starting antifungal therapy to prevent life-threatening CNS Immune Reconstitution Inflammatory Syndrome (IRIS) .
- C. CD4 < 50 cells/mcL
- Mycobacterium avium Complex (MAC)
Clinical Presentation: Disseminated multiorgan disease presenting with constitutional symptoms (hectic fevers, drenching night sweats, profound weight loss, fatigue), abdominal pain, chronic diarrhea, hepatosplenomegaly, severe anemia, and markedly elevated serum alkaline phosphatase. Blood cultures for acid-fast bacilli (AFB) confirm diagnosis.
Primary Prophylaxis: Primary prophylaxis with Azithromycin is NO LONGER routinely recommended in individuals with HIV who immediately initiate effective ART, regardless of CD4 count.
Treatment: Clarithromycin (500 mg PO BID) or Azithromycin (500 mg PO daily) PLUS Ethambutol (15 mg/kg PO daily) for at least 12 months.
Cytomegalovirus (CMV) Retinitis
Clinical Presentation: Painless blurred vision, floaters, photopsia (flashing lights), and progressive visual field scotomas. Funduscopy reveals the pathognomonic "pizza-pie" or "brushfire" appearance: confluent yellowish-white retinal necrotic infiltrates with perivascular retinal hemorrhages .
Treatment: Oral Valganciclovir (900 mg PO BID x 14–21 days induction, then 900 mg daily maintenance) OR IV Ganciclovir. Immediate intravitreal ganciclovir/foscarnet injections are added for sight-threatening lesions involving or adjacent to the macula or optic nerve.
- 2. Sexually Transmitted Infections (STIs)
- Syphilis ( Treponema pallidum )
Stage Clinical Manifestations & Diagnostic Features Recommended Treatment Regimen
Primary Syphilis • Solitary, painless, indurated ulcer ( chancre ) with a clean base and raised, firm margins; • Non-tender, rubbery regional inguinal lymphadenopathy (heals spontaneously in 3–6 weeks) Benzathine Penicillin G 2.4 million units IM as a single dose
Secondary Syphilis • Disseminated stage occurring 4–10 weeks after chancre; • Symmetric, non-pruritic maculopapular rash involving the palms and soles ; • Condylomata lata (broad, moist, flat, highly infectious plaques in intertriginous/perianal regions); • Mucous patches, "moth-eaten" alopecia, generalized lymphadenopathy, constitutional symptoms Benzathine Penicillin G 2.4 million units IM as a single dose
Early Latent Syphilis • Asymptomatic infection acquired within the preceding < 1 year (documented by seroconversion or known exposure) Benzathine Penicillin G 2.4 million units IM as a single dose
Late Latent Syphilis / Latent of Unknown Duration • Asymptomatic infection acquired > 1 year ago or duration entirely unknown Benzathine Penicillin G 2.4 million units IM weekly for 3 consecutive doses (total 7.2 million units)
Tertiary Syphilis • Gummatous syphilis (destructive nodular/granulomatous lesions of skin and bones); • Cardiovascular syphilis (ascending aortic aneurysm, aortic regurgitation, "tree-bark" aortitis) Benzathine Penicillin G 2.4 million units IM weekly for 3 consecutive doses (total 7.2 million units)
Neurosyphilis / Ocular / Otosyphilis • Can occur at ANY stage of syphilis; • Meningovascular stroke, tabes dorsalis (ataxia, lancinating pains, loss of vibration/proprioception, Argyll Robertson pupils [accommodate to near vision but do not react to light]), general paresis (dementia, psychosis), uveitis, sensorineural hearing loss Aqueous Crystalline Penicillin G 18 to 24 million units/day IV (administered as 3–4 million units IV every 4 hours or continuous infusion) for 10 to 14 days
High-Yield Syphilis Management Pearls
Serologic Monitoring: Non-treponemal titers (RPR or VDRL) are used to monitor treatment response. A 4-fold decline in titer (e.g., from 1:32 down to 1:8) at 6 to 12 months indicates successful therapy.
Jarisch-Herxheimer Reaction: Acute, benign, self-limiting febrile reaction (fevers, rigors, headache, tachycardia, transient exacerbation of rash) occurring within 2 to 24 hours after the first dose of penicillin. Caused by massive spirochetal lysis releasing pyrogenic endotoxins. Managed supportively with antipyretics (acetaminophen); do not stop penicillin.
Penicillin Allergy in Pregnancy: Penicillin is the only proven therapy effective for treating maternal syphilis and preventing congenital syphilis. Pregnant patients with documented penicillin allergy MUST undergo penicillin skin testing and oral desensitization , followed by treatment with Benzathine Penicillin G. (Doxycycline is strictly contraindicated in pregnancy).
Gonorrhea & Chlamydia (CDC 2021 Treatment Guidelines)
Uncomplicated Urogenital, Anorectal, or Pharyngeal Gonorrhea ( Neisseria gonorrhoeae ):
Ceftriaxone 500 mg IM single dose (for body weight <150 kg; administer 1,000 mg IM if body weight >=150 kg).
Note: Azithromycin 1 g is NO LONGER co-administered with ceftriaxone due to widespread macrolide resistance.
Chlamydia Trachomatis ( Chlamydia trachomatis ):
Doxycycline 100 mg PO twice daily for 7 days (first-line regimen; superior microbiological cure rates compared to single-dose azithromycin, especially for rectal chlamydia).
Alternative for pregnancy: Azithromycin 1 g PO as a single dose .
Empiric Co-Treatment Rule: If N. gonorrhoeae is diagnosed via NAAT and C. trachomatis infection has not been ruled out , administer Ceftriaxone 500 mg IM single dose PLUS Doxycycline 100 mg PO BID for 7 days .