Infectious Diseases

A

• Acute Bacterial Meningitis (Adults) — Early Antibiotics, Dexamethasone, and LP/CT Algorithm

  Suspect with fever, neck stiffness, and altered mental status. Give empiric antibiotics immediately after blood cultures; add dexamethasone before or with first dose for suspected pneumococcal meningitis. CT before LP only if focal deficit, papilledema, new seizure, immunocompromise, or altered consciousness.
• Acute Bacterial Meningitis (Adults) — Empiric Therapy, Dexamethasone, and LP Strategy

  Treat immediately: draw blood cultures, give dexamethasone and empiric antibiotics before/with first dose, and obtain CT only when indicated (focal deficit, immunocompromise, papilledema). Tailor regimen by age/risk (Listeria coverage if >50 or immunocompromised).
• Acute Pyelonephritis — Adult

  Fever and flank pain with pyuria/bacteriuria; treat with appropriate oral or IV antibiotics based on severity and local resistance; image if severe, obstructed, or not improving; consider admission for high-risk.
• Acute Pyelonephritis — Adult Management

  Fever, flank pain, and urinary symptoms; send cultures; start empiric antibiotics tailored to local resistance and risk factors; image when complicated or not improving.
• Adult Bacterial Meningitis — Empiric Antibiotics, Dexamethasone, and LP Strategy

  Give empiric antibiotics immediately after blood cultures; dexamethasone should precede or accompany first antibiotic dose in suspected pneumococcal meningitis. CT before LP if focal deficit, seizure, immunocompromise, or papilledema; otherwise proceed directly to LP.

B

• Bacterial Meningitis — Adult Empiric Therapy

  Suspect with fever, neck stiffness, and altered mental status; give empiric IV antibiotics and dexamethasone without delay, obtain blood cultures, and perform lumbar puncture when safe.
• Bacterial Meningitis — Adult Empiric Therapy & Dexamethasone

  Medical emergency: give empiric IV antibiotics immediately after cultures; dexamethasone before/with first dose for suspected pneumococcus; CT before LP only for specific indications.

C

• Cellulitis and Abscess — ED Management

  Differentiate purulent abscess requiring incision and drainage from nonpurulent cellulitis; choose antibiotics based on severity and MRSA risk; ensure follow up.
• Cellulitis vs Abscess — Diagnosis & Treatment

  Distinguish cellulitis from abscess clinically; use bedside ultrasound to detect pus; I&D is first-line for abscess; antibiotics target streptococci ± MRSA based on severity and risk; mark borders and reassess.
• Clostridial Myonecrosis (Gas Gangrene) — Immediate Debridement and Antitoxin Strategy

  Fulminant myonecrosis with excruciating pain, systemic toxicity, crepitus, and skin discoloration; often after trauma or injection. Management is immediate wide surgical debridement, high‑dose IV penicillin plus clindamycin for toxin suppression, hemodynamic support, and consideration of hyperbaric oxygen as an adjunct.
• Clostridioides difficile Infection — Adult

  Test only patients with unexplained new diarrhea; use toxin-based algorithm; treat with fidaxomicin (preferred) or oral vancomycin; consider bezlotoxumab and FMT for recurrences.
• Clostridioides difficile — Fulminant Management

  Fulminant disease requires high dose oral vancomycin plus IV metronidazole and urgent surgical evaluation for toxic colitis.
• Community Acquired Pneumonia — Adult Management

  Risk stratify for site of care, give guideline concordant antibiotics, and reassess early for response and complications.
• Community-Acquired Pneumonia (Adults) — Severity Scores, Empiric Antibiotics, and Disposition

  Fever, cough, pleuritic chest pain with infiltrate on imaging. Use PSI or CURB‑65 for disposition. Start guideline‑concordant empiric antibiotics and consider MRSA/Pseudomonas coverage based on risk factors; treat for atypicals as indicated and switch to oral therapy when stable.
• Community-Acquired Pneumonia — Adult

  Risk stratify (PSI/CURB-65), obtain CXR, start empiric antibiotics promptly; consider extended-spectrum coverage for comorbidities; switch to oral when stable and treat 5–7 days if responsive.
• Community‑Acquired Pneumonia in Adults — Outpatient vs Inpatient

  Guideline-based approach to Community‑Acquired Pneumonia in Adults — Outpatient vs Inpatient: diagnostic criteria, risk stratification, therapy, and follow-up.
• Cryptococcal Meningitis in HIV — Induction to Maintenance

  Treat with induction (amphotericin B + flucytosine), consolidation (high‑dose fluconazole), and maintenance; aggressively manage intracranial pressure; delay ART to reduce IRIS risk.

G

• Gonorrhea & Chlamydia — 2025 Treatment Guidance

  Treat gonorrhea with ceftriaxone IM; add doxycycline if chlamydia not excluded. Treat chlamydia with doxycycline; azithromycin in pregnancy. Test and treat partners; retest at 3 months.

H

• Herpes Zoster — Antivirals & Postherpetic Neuralgia Prevention

  Start antivirals within 72 hours to reduce acute pain and complications; provide analgesia and counsel on vaccination; treat ophthalmic involvement urgently.
• Hospital- and Ventilator-Associated Pneumonia — Adult

  Diagnose with new infiltrate plus clinical criteria; start empiric therapy based on MDR risk and local antibiogram; de-escalate with cultures; typical duration ~7 days if improving.
• Hospital‑Acquired & Ventilator‑Associated Pneumonia — Empiric Therapy

  HAP/VAP: cover likely pathogens based on local antibiogram and risk factors for MRSA/Pseudomonas; obtain cultures before antibiotics; de‑escalate and treat ~7 days if improving.

I

• Infective Endocarditis — Diagnosis and Treatment

  Suspect with persistent bacteremia or typical signs; obtain multiple blood cultures and echocardiography; begin empiric therapy after cultures; surgery for heart failure, uncontrolled infection, or embolic risk.
• Infective Endocarditis — Duke Criteria, Empiric Therapy, and Surgical Indications

  Suspect with fever and new murmur, embolic phenomena, or positive blood cultures. Obtain 3 sets of blood cultures before antibiotics when feasible; use Duke criteria for diagnosis. Start empiric therapy based on native vs prosthetic valve and tailor to cultures; identify indications for surgery (heart failure, uncontrolled infection, embolic risk).
• Infective Endocarditis — Modified Duke Criteria, Empiric Therapy, and Surgical Indications

  Suspect IE with persistent bacteremia, new murmur, or emboli. Obtain three sets of blood cultures before antibiotics when possible, apply Modified Duke Criteria, start empiric IV therapy tailored to native vs prosthetic valve and MRSA risk, and evaluate for surgery when heart failure, uncontrolled infection, or embolic risk is present.
• Influenza in Adults — Testing & Antivirals

  Test when results will change management; start antivirals promptly for severe, progressive, or high‑risk patients, and for others within 48 hours of symptom onset.

L

• Lemierre Syndrome — Fusobacterium Septic Thrombophlebitis of the Internal Jugular

  Young, previously healthy patient with recent oropharyngeal infection develops fever, neck pain, and septic emboli. Suspect Lemierre syndrome—septic thrombophlebitis of the internal jugular vein—most often due to Fusobacterium necrophorum.

N

• Native Vertebral Osteomyelitis — Diagnosis & Treatment

  Suspect with back pain, fever, and elevated CRP/ESR. MRI is diagnostic; obtain blood cultures and biopsy if needed. Treat with 6 weeks of targeted antibiotics; surgery for instability, abscess, or neurologic deficits.
• Necrotizing Otitis Externa — Pseudomonas Coverage and Skull-Base Osteomyelitis

  Severe external otitis in diabetics/immunocompromised with granulation tissue and skull-base osteomyelitis risk. Obtain imaging for extent and initiate anti-pseudomonal therapy with close ENT follow-up.
• Necrotizing Soft Tissue Infection — Early Debridement, Broad Antibiotics, and Toxin Suppression

  NSTI is a surgical emergency. High suspicion with pain out of proportion, bullae, crepitus, or systemic toxicity mandates immediate broad-spectrum antibiotics and urgent operative debridement; repeat debridements are common. Add clindamycin for toxin suppression in suspected streptococcal/staphylococcal disease.
• Neutropenic Fever — Empiric Antibiotics

  Oncologic emergency: start broad spectrum antipseudomonal beta lactam within 60 minutes after cultures; risk stratify for outpatient vs inpatient management.
• Neutropenic Fever — Oncologic Emergency

  Start antipseudomonal IV antibiotics within 60 minutes; risk stratify for inpatient vs outpatient therapy; escalate for instability or persistent fever.

R

• Rabies Post Exposure Prophylaxis — Wounds and Vaccination

  Immediate wound irrigation plus appropriate vaccine series and human rabies immune globulin for indicated exposures; coordinate with public health.

S

• Septic Arthritis (Native Joint) — Arthrocentesis, Empiric Coverage, and Washout

  Acute monoarthritis with fever and elevated inflammatory markers warrants urgent arthrocentesis. Start empiric IV antibiotics after cultures and arrange operative washout for large joints or if poor response to needle drainage.
• Spinal Epidural Abscess — MRI, Targeted IV Antibiotics, and Surgical Decompression

  Fever, back pain, and neurologic deficits constitute the classic triad but are often incomplete. Maintain high suspicion in IVDU, diabetes, or bacteremia. Obtain urgent MRI, start broad IV antibiotics, and coordinate early surgical decompression for neurologic deficits or failure of medical therapy.
• Spinal Epidural Abscess — Red Flags, MRI, and Early Decompression

  Back pain with fever and new focal neurologic deficits warrants urgent MRI for spinal epidural abscess; start empiric anti-staphylococcal therapy and obtain early neurosurgical consultation for decompression when deficits or instability are present.
• Spontaneous Bacterial Peritonitis — Empiric Therapy

  Perform diagnostic paracentesis in all hospitalized patients with cirrhosis and ascites; treat SBP with third generation cephalosporin and give albumin in select cases.
• Spontaneous Bacterial Peritonitis — Empiric Third-Gen Cephalosporin and Albumin

  Suspect SBP in cirrhosis with ascites and abdominal pain or encephalopathy. Diagnose via ascitic PMN ≥250/µL; start empiric third-generation cephalosporin and give albumin to reduce renal failure in high-risk cases.
• Staphylococcus aureus Bacteremia — Evaluation & Source Control

  SAB is never a contaminant until proven otherwise. Obtain repeat blood cultures, evaluate for endocarditis, source control, and treat with pathogen‑directed therapy for adequate duration.
• Syphilis — Staging, Testing, and Treatment

  Use treponemal + non‑treponemal tests for diagnosis; treat with stage‑appropriate benzathine penicillin; manage neurosyphilis with IV penicillin; ensure follow‑up titers and partner management.

T

• Tetanus Prophylaxis — Wound Management

  Assess wound type and vaccination status to decide on Td/Tdap booster and tetanus immune globulin; perform thorough irrigation and debridement.
• Toxoplasmosis in HIV — CNS Disease Management

  Empiric therapy for typical ring‑enhancing brain lesions in AIDS while confirming diagnosis; pyrimethamine + sulfadiazine + leucovorin is standard; treat acute phase ≥6 weeks, then chronic maintenance.