When to intubate in GCS?

GCS ≤ 8 requires intubation for airway protection. The patient cannot protect their own airway at this level of consciousness. Motor score is the most prognostically important component.

What is the best initial fluid for sepsis resuscitation?

Lactated Ringer's (LR) is the preferred resuscitation fluid. The SMART trial (2018) showed balanced crystalloids reduced death, new renal failure, and persistent renal dysfunction compared to normal saline.

When to start vasopressors in septic shock?

Start norepinephrine (first-line vasopressor) if MAP remains < 65 mmHg after initial 30 mL/kg crystalloid resuscitation, or earlier if patient is profoundly hypotensive. Do not delay pressors to complete full fluid resuscitation.

Why can serum uric acid be normal during acute gout?

During acute inflammation, IL-6 increases renal urate excretion and redistributes urate from plasma to tissues. Up to 40% of acute gout flares have normal serum uric acid. Joint aspiration with polarized microscopy is needed for definitive diagnosis.

How do you distinguish lupus flare from infection in SLE?

Key clues: CRP is low/normal in flare but elevated in infection. Complement (C3/C4) drops in flare but is normal/elevated in infection. Procalcitonin is elevated in bacterial infection but normal in flare. Anti-dsDNA rises in flare, stable in infection.

What is the difference between DKA and HHS?

DKA features acidosis (pH 600), hyperosmolality (> 320), and minimal ketosis -typically in Type 2 DM. DKA requires insulin drip; HHS requires aggressive fluid resuscitation first.

When to give tPA in acute ischemic stroke?

IV alteplase (tPA) can be given within 4.5 hours of last known well time in eligible patients. CT head must rule out hemorrhage first. For large vessel occlusion, mechanical thrombectomy can be performed up to 24 hours with favorable imaging.

What antibiotics for community-acquired pneumonia?

Inpatient non-ICU: ceftriaxone + azithromycin. ICU: ceftriaxone + azithromycin (add vancomycin if MRSA risk). Outpatient healthy: amoxicillin. Outpatient with comorbidities: augmentin + azithromycin or respiratory fluoroquinolone. Duration: 5 days if clinically stable for 48 hours.

How to interpret iron studies?

Iron deficiency: low ferritin (< 30), high TIBC, low iron, low transferrin saturation (< 20%). Anemia of chronic disease: normal/high ferritin (acute phase reactant), low TIBC, low iron. A ferritin of 50-100 in an inflamed patient may still represent iron deficiency.

What is the correction rate for hyponatremia?

Correct sodium no more than 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS). For symptomatic severe hyponatremia with seizures, give 3% hypertonic saline 100-150 mL bolus over 10-20 minutes. If overcorrected, use D5W + DDAVP rescue protocol.

When to start antibiotics in meningitis?

Within 30-60 minutes. Do NOT delay antibiotics for LP or CT. Draw blood cultures, start empiric antibiotics (vancomycin + ceftriaxone ± ampicillin if > 50 or immunocompromised), then perform LP when possible. Dexamethasone should be given before or with the first antibiotic dose.

DOACs vs warfarin in antiphospholipid syndrome?

DOACs are contraindicated in APS. The TRAPS trial (2018) showed rivaroxaban was inferior to warfarin with more thrombotic events in triple-positive APS patients. Warfarin with INR target 2-3 is the standard for APS, indefinitely.

How to manage scleroderma renal crisis?

ACE inhibitors (captopril) are life-saving -start immediately and titrate aggressively. Do NOT hold for rising creatinine. Steroids > 15 mg prednisone per day precipitate scleroderma renal crisis. ARBs are NOT a substitute -evidence is only for ACEi.

What are the 4 pillars of heart failure treatment?

Guideline-directed medical therapy (GDMT) for HFrEF: (1) ARNI or ACEi/ARB, (2) beta-blocker (carvedilol, metoprolol succinate, or bisoprolol), (3) MRA (spironolactone or eplerenone), (4) SGLT2 inhibitor (dapagliflozin or empagliflozin). All four should be initiated and titrated to target doses.

RoundsRx

Dashboard

Overview

Recent

Rotations

Quick Reference

Antibiotic Guide Analgesia Guide Sedation Guide Bowel Regimen Electrolyte Replacement Pain Management & Conversions Drug Interactions Anticoag Reversal IV Fluid Guide Inotropes Guide Vasopressors Insulin Guide Code Blue & Rapid Response Procedures Guide ECG Interpretation Lab Interpretation Radiology Quick Ref GCS Pocket Card Admission Orders & I-PASS Landmark Trials

Tools

💎 Clinical Pearls 🧠 Pimp Me Quiz 🧮 Clinical Calculators 📰 What's New 🎓 Intern Survival Guide ✅ Rounding Checklists 🩺 Procedure Guides ⚡ Electrolyte Replacement 💧 IV Fluids Guide 🩸 Transfusion Guide 💓 ECG Pattern Guide 🧪 Lab Interpretation Guide 📱 QR Poster 🔗 Resources 🎙️ Channels & Podcasts 🎮 Medical Games 🏛️ Famous Cases 🎬 Media Library

ℹ️ About

Available offline

IDCommon

Osteomyelitis

Infection of bone -most commonly S. aureus. Hematogenous in children, contiguous spread in adults (diabetic foot, decubitus ulcers, post-surgical). MRI is the imaging gold standard. Bone biopsy is the diagnostic gold standard. Treatment is 6 weeks of targeted antibiotics -oral step-down is non-inferior to IV (OVIVA 2019).

🔍 Overview

Classification

Type	Mechanism	Typical Patient	Common Organisms
Hematogenous	Bacteremia seeds bone (metaphysis in children, vertebral body in adults)	Children, IVDU (vertebral), sickle cell disease	S. aureus (#1 overall). Salmonella in SCD. Pseudomonas in IVDU.
Contiguous spread	Direct extension from adjacent soft tissue infection, open fracture, or surgery	Post-surgical, trauma, diabetic foot ulcers, decubitus ulcers	S. aureus, coagulase-negative staph (hardware). Polymicrobial (diabetic foot -add gram-negatives + anaerobes).
Vascular insufficiency	Chronic ischemia + minor trauma/ulceration → infection spreads to bone	Diabetic foot, peripheral arterial disease	Polymicrobial: S. aureus, Streptococcus, Enterococcus, gram-negatives (E. coli, Proteus), anaerobes (Bacteroides).

Acute vs Chronic

Feature	Acute	Chronic
Duration	< 2 weeks of symptoms	> 6 weeks, or recurrent
Pathology	Suppurative infection, edema	Sequestrum (dead bone), involucrum (new bone around dead bone), sinus tracts
Treatment	Antibiotics often curative alone	Usually requires surgical debridement + prolonged antibiotics

Probe-to-bone test: In diabetic foot ulcers, if a sterile metal probe reaches bone through the ulcer, the positive predictive value for osteomyelitis is ~89%. Simple, bedside, no imaging needed.

🚨 Management

Antibiotic Duration

Standard: 6 weeks of targeted antibiotics. Oral step-down after initial IV is acceptable -OVIVA trial showed oral antibiotics were non-inferior to IV for bone and joint infections at 1 year OVIVA, 2019.

Empiric Therapy (Before Culture Data)

Scenario	Empiric Regimen	Rationale
Native bone, acute	Vancomycin (Vancocin) (MRSA coverage) + Ceftriaxone (Rocephin) 2g IV daily (gram-negatives)	Covers MRSA + gram-negatives while awaiting cultures. Narrow once sensitivities return.
Diabetic foot	Vancomycin (Vancocin) + Piperacillin-tazobactam (Zosyn) 3.375g IV q6h	Polymicrobial -need MRSA + gram-negatives + anaerobic coverage.
Post-surgical / hardware	Vancomycin (Vancocin) + Cefepime (Maxipime) 2g IV q8h	Covers MRSA + Pseudomonas + skin flora. Hardware infections often need surgical removal.
Vertebral	Vancomycin (Vancocin) + Ceftriaxone (Rocephin)	S. aureus is #1. If IVDU, cover Pseudomonas (use cefepime instead of ceftriaxone).
Sickle cell disease	Ceftriaxone (Rocephin) 2g IV daily	Salmonella is #1 in SCD (not S. aureus). Ceftriaxone covers Salmonella + S. aureus.

Surgical Indications

Chronic osteomyelitis with sequestrum or sinus tracts
Failed medical therapy (persistent infection after adequate antibiotics)
Hardware-associated infection -often requires implant removal
Abscess requiring drainage
Spinal epidural abscess with neurological compromise -neurosurgical emergency
Diabetic foot with non-healing ulcer and extensive bony involvement -may need amputation

Do NOT start antibiotics before bone biopsy/cultures if the patient is stable. Pre-biopsy antibiotics reduce culture yield and may lead to months of unnecessarily broad therapy. Exception: septic or hemodynamically unstable patients -treat empirically, culture what you can.

🧪 Workup

Diagnostic Evaluation

ESR and CRP -elevated in >90% of cases. ESR >70 is highly suggestive. Use to monitor treatment response.
Blood cultures (×2 sets) -positive in ~50% of hematogenous osteomyelitis. Always obtain before antibiotics.
CBC -WBC may be normal in chronic osteomyelitis. Left shift suggests acute infection.
Plain radiographs -first-line imaging. Changes take 10–14 days to appear (periosteal reaction, lytic lesions). Normal X-ray does NOT rule out early osteomyelitis.
MRI with gadolinium -imaging gold standard. Sensitivity 90–100%, specificity 80–90%. Shows bone marrow edema, soft tissue extent, abscess.
Bone biopsy with culture -diagnostic gold standard. Identifies organism and sensitivities. Essential for targeted therapy. IR-guided or open surgical.
Probe-to-bone test -bedside test for diabetic foot ulcers. PPV ~89% if positive.

MRI cannot distinguish osteomyelitis from Charcot arthropathy in diabetic feet -both show bone marrow edema. Clinical correlation and biopsy are essential in this setting.

💊 Medications

Targeted Therapy (Based on Culture)

Organism	First-Line	Alternative	Duration / Notes
MSSA* *= Methicillin-Sensitive Staph aureus	Nafcillin (Nallpen) 2g IV q4h or Cefazolin (Ancef) 2g IV q8h	Oral step-down: Cephalexin (Keflex) 1g PO QID or Dicloxacillin (Dynapen) 500mg PO QID	6 weeks. IV × 1–2 weeks then oral step-down per OVIVA. Cefazolin preferred for ease of outpatient dosing (q8h vs q4h).
MRSA* *= Methicillin-Resistant Staph aureus	Vancomycin (Vancocin) 15–20 mg/kg IV q8–12h (target AUC/MIC 400–600)	Oral step-down: TMP-SMX (Bactrim) DS 1–2 tabs PO BID + Rifampin (Rifadin) 300mg PO BID	6 weeks. Rifampin for biofilm penetration (hardware infections). Never use rifampin monotherapy -resistance develops rapidly.
Streptococcus	Ceftriaxone (Rocephin) 2g IV daily	Penicillin G or Amoxicillin (Amoxil) 1g PO TID	6 weeks. Strep are reliably penicillin-sensitive.
Pseudomonas	Cefepime (Maxipime) 2g IV q8h or Piperacillin-tazobactam (Zosyn)	Ciprofloxacin (Cipro) 750mg PO BID (oral option with good bone penetration)	6 weeks. Cipro has excellent oral bioavailability and bone penetration -preferred oral agent for Pseudomonas osteo.
Salmonella (SCD)	Ceftriaxone (Rocephin) 2g IV daily	Ciprofloxacin (Cipro) 500mg PO BID	6 weeks. Most common cause of osteomyelitis in sickle cell disease.
Polymicrobial (diabetic foot)	Vancomycin (Vancocin) + Piperacillin-tazobactam (Zosyn)	Oral step-down: Amoxicillin-clavulanate (Augmentin) 875mg PO BID + TMP-SMX (Bactrim) (if MRSA)	6 weeks. Surgical debridement is almost always needed. Vascular assessment essential.

📋 On Rounds

Pimp Questions

What is the most common organism causing osteomyelitis overall? In sickle cell disease?

Overall: S. aureus -accounts for ~60% of all osteomyelitis. In sickle cell disease: Salmonella -infarcted bone from vaso-occlusive crises is a perfect growth medium. This is a classic boards distinction. However, S. aureus is still #1 for septic arthritis in SCD.

Why is bone biopsy considered the gold standard over blood cultures?

Blood cultures are positive in only ~50% of hematogenous osteomyelitis and even less in contiguous spread. Bone biopsy with culture identifies the exact organism and sensitivities, allowing targeted narrow-spectrum therapy for a 6-week course. Without culture data, you may commit a patient to 6 weeks of unnecessarily broad-spectrum antibiotics with more side effects, higher cost, and greater resistance risk.

Can you treat osteomyelitis with oral antibiotics?

Yes. The OVIVA trial (2019) randomized 1,054 patients with bone/joint infections to IV vs oral antibiotics after initial surgical management. Oral was non-inferior at 1 year (treatment failure 14.6% oral vs 14.1% IV). Key caveat: patients had a defined organism with known oral sensitivities, and oral agents with good bone penetration were used (fluoroquinolones, rifampin combinations, linezolid).

Why should you never use rifampin as monotherapy?

Rifampin has excellent biofilm penetration (critical for hardware-associated infections) and good bone penetration. However, resistance develops extremely rapidly with monotherapy -single-step mutations in the rpoB gene occur at a rate of ~10⁻⁸, which is high enough to select resistant mutants within days. Always combine with another active agent (e.g., TMP-SMX, fluoroquinolone, vancomycin).

Clinical Examples

📋 Case 1, Vertebral Osteomyelitis from Bacteremia

Patient: 62M IVDU with 3 weeks of progressive back pain and low-grade fevers. MRI spine: L3-L4 vertebral body edema, disc enhancement, paravertebral phlegmon. Blood cultures: MSSA. No epidural abscess.

Key findings: Vertebral osteomyelitis (most common location for hematogenous osteomyelitis in adults). IVDU + S. aureus bacteremia. Must rule out epidural abscess (MRI with contrast is the gold standard). No surgical indication without abscess or instability.

Management:

Nafcillin 2g IV q4h × 6 weeks (MSSA → beta-lactam preferred over vancomycin for efficacy)
Add rifampin 300 mg PO BID after 2 weeks of IV therapy (enhances biofilm penetration, always in combination, never alone)
TTE → if positive or high suspicion: TEE to rule out endocarditis (IVDU + S. aureus = 30% concurrent IE)
Pain management: NSAIDs + acetaminophen; opioids PRN initially; gabapentin for neuropathic component
PICC line for outpatient IV antibiotics (OPAT) if clinically stable after initial improvement

Teaching point: Every case of vertebral osteomyelitis needs an MRI of the ENTIRE spine (multifocal in 10-15%) and evaluation for endocarditis (especially S. aureus). Blood cultures are positive in 50-60%, get them before antibiotics.

📋 Case 2, Diabetic Foot Osteomyelitis

Patient: 68M with T2DM (A1c 10.2), presents with non-healing plantar ulcer × 3 months over 2nd metatarsal head. Ulcer depth: bone is palpable with sterile probe ("probe to bone" positive). XR: periosteal reaction and cortical erosion of 2nd metatarsal.

Key findings: Diabetic foot osteomyelitis, "probe to bone" test has 89% PPV for osteomyelitis when positive in a diabetic foot ulcer. X-ray changes confirm chronic osteomyelitis (periosteal reaction, cortical destruction).

Management:

MRI foot (best imaging) to delineate extent of bone involvement and surgical planning
Bone biopsy + culture before antibiotics if possible (wound swabs are unreliable, contaminated with skin flora)
Empiric: vancomycin + piperacillin-tazobactam (cover MRSA + GNR + anaerobes) → narrow based on bone culture
Surgical debridement or limited amputation (ray amputation) for devitalized bone, antibiotics alone cannot cure dead bone
Offloading: total contact cast or removable walking boot (pressure relief is essential for healing)

Teaching point: Wound swab cultures do NOT reflect bone pathogens, bone biopsy is the gold standard for guiding antibiotic therapy. If bone is visible or palpable in a diabetic foot ulcer, treat as osteomyelitis. MRI is the best imaging modality (sensitivity 90%, specificity 80%).

📋 Case 3, Prosthetic Joint Infection

Patient: 74F, 2 years post-right TKR. Progressive knee pain and swelling × 6 weeks, low-grade fever. Knee aspirate: WBC 28,000 (80% PMNs), culture growing coagulase-negative Staph (CoNS). CRP 68, ESR 82.

Key findings: Chronic prosthetic joint infection (PJI), onset > 3 months post-op. CoNS is #1 organism in chronic PJI (biofilm former on prosthetic material). Synovial WBC > 3,000 with > 80% PMNs meets MSIS criteria for PJI in a prosthetic joint.

Management:

Two-stage exchange arthroplasty (gold standard for chronic PJI): remove prosthesis → antibiotic spacer × 6-8 weeks → reimplant new prosthesis
IV vancomycin × 6 weeks (CoNS, often methicillin-resistant) + rifampin 300 mg PO BID (biofilm penetration)
Alternative (select cases): DAIR (debridement, antibiotics, implant retention) if: < 3 weeks of symptoms, stable implant, susceptible organism
ID consult for antibiotic optimization and duration
Withhold reimplantation until CRP normalizes and repeat aspiration is negative

Teaching point: Rifampin is the key drug in prosthetic joint infections, it penetrates biofilms that other antibiotics cannot reach. But NEVER use rifampin alone (rapid resistance in days). Always combine with vancomycin, TMP-SMX, or a fluoroquinolone.

📣 Sample Presentation

One-Liner

"Mrs. Garcia is a 62-year-old woman with poorly controlled diabetes (A1c 9.8%) and a non-healing right plantar ulcer × 3 months, now with exposed bone on probing and MRI showing marrow edema in the 2nd metatarsal head consistent with osteomyelitis."

Key Points to Cover on Rounds

Diabetic foot ulcer with positive probe-to-bone. MRI confirms osteomyelitis of 2nd metatarsal head -no abscess, no soft tissue collection. ESR 88, CRP 6.4. Blood cultures × 2 pending. IR-guided bone biopsy scheduled tomorrow -holding antibiotics until culture obtained (patient is hemodynamically stable). Vascular surgery consulted for ABI assessment -pedal pulses palpable. Podiatry involved for wound care. Plan: bone biopsy → targeted antibiotics × 6 weeks, oral step-down when organism and sensitivities known. Glucose management with insulin drip per endocrine.

Monitoring Parameters

ESR and CRP -check weekly. CRP normalizes faster (1–2 weeks). ESR may take weeks to decline. Failure to trend down suggests treatment failure or undrained collection.
CBC with differential -weekly. Monitor WBC normalization.
Vancomycin levels -if on vancomycin, target AUC/MIC 400–600. Check trough before 4th dose, then 1–2× weekly.
Renal function (BMP) -weekly if on vancomycin or aminoglycosides. Watch for nephrotoxicity.
LFTs -if on rifampin (hepatotoxic). Baseline then q2 weeks.
PICC line site -daily inspection for infection, thrombosis if on prolonged IV therapy.
Repeat imaging -not routine. Repeat MRI only if clinical concern for treatment failure or new collection. Imaging lags behind clinical improvement.

⚡ Summary

Microbiology

S. aureus is #1 overall. Salmonella in SCD. Pseudomonas in IVDU. Polymicrobial in diabetic foot (staph + gram-negatives + anaerobes).

Diagnosis

MRI = imaging gold standard (sens 90–100%). Bone biopsy with culture = diagnostic gold standard. Probe-to-bone test for diabetic foot (PPV ~89%). Plain films take 10–14 days to show changes.

Treatment Duration

6 weeks of targeted antibiotics. Oral step-down is non-inferior to IV (OVIVA 2019). Hold antibiotics for biopsy if patient is stable.

MSSA / MRSA

MSSA: nafcillin or cefazolin → oral cephalexin. MRSA: vancomycin → oral TMP-SMX + rifampin. Never use rifampin monotherapy.

Surgical Indications

Chronic with sequestrum, failed medical therapy, hardware infection (implant removal), abscess drainage, spinal epidural abscess with neuro compromise.

Monitoring

ESR/CRP weekly (CRP normalizes faster). Vancomycin AUC/MIC if applicable. BMP for nephrotoxicity. Repeat MRI only if treatment failure suspected.