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.

Pneumonia -CAP & HAP Management -RoundsRx

🔍 Overview

Classification

Type	Definition	Common Organisms	Empiric Antibiotics
CAP (Community-acquired)	Acquired outside hospital, or < 48h after admission	S. pneumoniae (#1), H. influenzae, Mycoplasma, Chlamydophila, Legionella, respiratory viruses	Outpatient (healthy): Amoxicillin 1g TID Outpatient (comorbid): Amox-clav + azithromycin Inpatient: Ceftriaxone IV + azithromycin IV ICU: Same ± vanc/linezolid if MRSA risk (linezolid if severe)
HAP* (Hospital-acquired) *HAP = Hospital-Acquired Pneumonia (≥48h after admission)	≥ 48h after admission, not intubated at time of infection	MRSA, Pseudomonas, Klebsiella, Acinetobacter, Enterobacter	Pip-tazo 4.5g q6h or cefepime 2g q8h + vancomycin or linezolid (MRSA; linezolid if severe) Meropenem if ESBL/MDR risk Pip-tazo if anaerobic concern (aspiration + abscess/empyema). Cefepime if no anaerobes -especially with vanc (↓ AKI) ACORN, 2024
VAP* (Ventilator-associated) *VAP = Ventilator-Associated Pneumonia (≥48h after intubation)	≥ 48h after intubation	Same as HAP + higher Pseudomonas and MDR organisms	Pip-tazo or cefepime or meropenem + vanc or linezolid (MRSA; linezolid if severe) ± double Pseudomonas coverage if MDR risk Pip-tazo if anaerobic risk (aspiration, abscess). Cefepime + vanc preferred (lower nephrotoxicity). Need cefepime + anaerobes → add metronidazole
Aspiration pneumonia	Witnessed or high-risk aspiration event (AMS, dysphagia, GERD). Classically RLL or posterior segments of upper lobes (gravity-dependent).	Same as CAP -S. pneumoniae, H. influenzae, S. aureus, Enterobacteriaceae. Anaerobes are NOT the primary cause (old teaching). Anaerobes only significant if: lung abscess, empyema, necrotizing PNA, or poor dentition + indolent course.	Acute: Treat like CAP (ceftriaxone + azithro) If abscess/empyema/necrotizing: ADD anaerobic coverage -amp-sulbactam 3g q6h or pip-tazo or metronidazole Chemical pneumonitis = NO abx

⚠️ HCAP is no longer a recognized category (ATS/IDSA 2016 eliminated it).
Old teaching: Hospitalization within 90 days, nursing home residence, hemodialysis, or home wound care = "Healthcare-Associated Pneumonia" → treat like HAP with broad-spectrum antibiotics.
Current teaching: HCAP led to massive over-treatment, most of these patients had CAP organisms, not MDR bugs. Increased C. diff and worse outcomes. Now: classify as CAP and assess individual MDR risk factors (prior MRSA culture, prior Pseudomonas culture, IV antibiotics within 90 days, structural lung disease) to decide if broader coverage is needed.

Severity Scores & Severe CAP Definitions

Different scores answer different questions. The default "severe CAP" definition residents are expected to know is IDSA/ATS 2019 (1 major OR ≥ 3 minor). CURB-65 and PSI are separate severity scores used alongside it. Click any heading below to expand.

IDSA / ATS 2019 criteria STANDARD
Use to decide: ICU admission. 1 major OR ≥ 3 minor = severe CAP.

Used for the ICU admission decision. 1 major OR ≥ 3 minor criteria = severe CAP.

Major criteria (any 1 = severe CAP)
Septic shock requiring vasopressors
Respiratory failure requiring mechanical ventilation

Minor criteria (need ≥ 3 = severe CAP)	Threshold
Respiratory rate	≥ 30
PaO2 / FiO2	≤ 250
Multilobar infiltrates on imaging	present
Confusion / disorientation	present (new)
BUN (uremia)	≥ 20 mg/dL
WBC (leukopenia from sepsis)	< 4,000
Platelets (thrombocytopenia)	< 100,000
Temperature (hypothermia)	< 36°C
Hypotension requiring aggressive fluid resuscitation	present

What "severe CAP" triggers clinically:

ICU admission and closer monitoring for shock and respiratory failure.
Standard empiric regimen still: ceftriaxone + macrolide (or respiratory fluoroquinolone). Severity alone does not change the antibiotics.
MRSA and Pseudomonas coverage are NOT added automatically. Add only if individual risk factors are present: prior respiratory isolation of that organism, hospitalization + IV antibiotics in the past 90 days, structural lung disease (bronchiectasis, severe COPD), or locally validated high prevalence. MRSA nasal PCR (~95% NPV) helps you stop empiric vanc/linezolid early.
Earlier consideration of adjunctive hydrocortisone (CAPE COD 2023). See the CAPE COD criteria collapsible below for steroid eligibility.

CURB-65
Use to decide: outpatient vs inpatient vs ICU at the front door. Score 0-1 home, 2 admit, 3-5 consider ICU.

Used to decide outpatient vs inpatient vs ICU at the front door. Not a strict "severe vs not" binary.

Letter	Criterion
C	Confusion (new AMS)
U	Urea (BUN) > 19 mg/dL (or > 7 mmol/L)
R	Respiratory rate ≥ 30
B	BP: SBP < 90 OR DBP ≤ 60
65	Age ≥ 65

Score	Disposition	30-day mortality
0-1	Outpatient (consider home Rx)	< 3%
2	Inpatient ward	~9%
3-5	ICU consideration	15-40%

Open CURB-65 calculator →

PSI / Pneumonia Severity Index
Use to decide: granular severity (Class I-V). More variables and better discrimination than CURB-65 but harder to calculate at bedside. PSI > 130 = CAPE COD steroid threshold.

Calculator-based, factors in age, comorbidities, exam findings, and labs. Stratifies into Class I-V. Class I-II outpatient, Class III observation, Class IV-V inpatient or ICU. PSI > 130 is the cutoff used by CAPE COD, 2023 for severe CAP eligible for hydrocortisone. PSI is more granular than CURB-65 (more variables, better discrimination) but harder to calculate at bedside without a calculator.

CAPE COD criteria
Use to decide: should I add hydrocortisone? Any one of: intubated, HFNC FiO2 ≥ 0.5 with P/F < 300, NIV with P/F < 300, or PSI > 130.

Used specifically when asking "should I add hydrocortisone?" Any ONE of the following triggers severe-CAP status for the steroid indication:

Intubated / mechanical ventilation
HFNC at FiO2 ≥ 0.5 with PaO2 / FiO2 < 300
Non-invasive ventilation with PaO2 / FiO2 < 300
PSI > 130

Overlaps with IDSA "severe" but operationalized slightly differently, focused on respiratory severity that inflammation modulation can help with. See When to Add Steroids in Pneumonia → for the full regimen.

💊 Treatment

Empiric Antibiotics

Setting	Regimen	Notes
CAP -Outpatient, no comorbidities	Amoxicillin (Amoxil) 1g TID 1ST LINE	Or doxycycline 100 mg BID. Or azithromycin 500 mg → 250 mg daily (only if local resistance < 25%).
CAP -Outpatient, with comorbidities	Amoxicillin-clavulanate 875 mg BID + azithromycin	Or respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) -monotherapy.
CAP -Inpatient (non-ICU)	Ceftriaxone 1–2g IV daily + azithromycin 500 mg IV daily STANDARD	Or respiratory FQ monotherapy. Duration: 5 days minimum Short-Course CAP Trial, 2016 -no benefit of longer courses if clinically stable at day 5.
CAP -ICU (severe)	Ceftriaxone (Rocephin) 2g IV + azithromycin (Zithromax) 500 mg IV	Add vancomycin or linezolid if MRSA risk factors (linezolid preferred if severe -superior lung penetration). Add piperacillin-tazobactam or cefepime if Pseudomonas risk. Always get blood cultures + sputum + Legionella/pneumococcal urine antigens.
HAP / VAP	Piperacillin-tazobactam (Zosyn) 4.5g IV q6h or cefepime 2g IV q8h or meropenem	Add vancomycin or linezolid for MRSA (linezolid if severe -superior lung penetration). Duration: 7 days ATS/IDSA HAP/VAP Guidelines, 2016. Shorter is better -reduces resistance.
Aspiration	Treat like CAP (ceftriaxone + azithro)	Anaerobes are NOT the primary cause -same organisms as CAP. Add anaerobic coverage (amp-sulbactam or pip-tazo) ONLY if: lung abscess, empyema, necrotizing PNA, or poor dentition + indolent course. Aspiration pneumonitis (chemical) = NO antibiotics.

Pip-Tazo vs Cefepime -When to Use Which

💊 Piperacillin-Tazobactam (Zosyn)

Coverage: Pseudomonas + gram-negatives + anaerobes

Aspiration with abscess/empyema/necrotizing PNA -anaerobic coverage built in
Intra-abdominal co-infection suspected
Poor dentition + indolent course (anaerobes likely)
Post-obstructive pneumonia (distal to tumor)
Mixed aerobic-anaerobic infection

⚠️ AKI risk with vancomycin: Pip-tazo + vanc has significantly higher AKI rates than cefepime + vanc ACORN, 2024 Pip-Tazo Nephrotoxicity Study, 2017. If using both, monitor Cr closely.

💊 Cefepime

Coverage: Pseudomonas + gram-negatives. NO anaerobic coverage.

HAP/VAP without anaerobic concern -standard nosocomial pneumonia
Preferred when combining with vancomycin -lower AKI risk ACORN, 2024
Neutropenic fever (first-line IDSA, 2010)
CKD/AKI patients on vancomycin -safer renal profile
No suspected anaerobic infection

⚠️ Neurotoxicity: Cefepime can cause seizures and encephalopathy, especially in renal impairment. Dose-adjust for CrCl. Monitor mental status.

Bottom line: Use pip-tazo when you need anaerobic coverage (aspiration with abscess/empyema, intra-abdominal source, necrotizing infection). Use cefepime when you don't need anaerobes -especially when pairing with vancomycin (lower nephrotoxicity). If you need cefepime + anaerobic coverage, add metronidazole 500 mg IV q8h separately.

MRSA risk factors: prior MRSA isolation, IV drug use, hospitalization within 90 days, hemodialysis, nursing home/LTAC residence. Pseudomonas risk: structural lung disease (bronchiectasis, CF), IV antibiotics within 90 days, prior Pseudomonas culture, immunosuppression.

🔄 Updated Practice: Old teaching: all "healthcare-associated" patients need MRSA coverage. HCAP was eliminated from 2019 ATS/IDSA guidelines because it led to massive overtreatment. Instead, get a nasal MRSA PCR swab -negative result has ~95% negative predictive value for MRSA pneumonia and can safely guide de-escalation.

Linezolid vs Vancomycin -Quick Decision Guide

Both cover MRSA, but they're NOT interchangeable. For MRSA pneumonia specifically, linezolid may be superior due to lung penetration. Know when to pick each.

Feature	Vancomycin	Linezolid (Zyvox)
Route	IV only (PO only for C. diff)	IV and PO (100% PO bioavailability)
MOA	Cell wall inhibitor -binds D-Ala-D-Ala, blocks peptidoglycan cross-linking. Bactericidal (slowly).	50S ribosome inhibitor -blocks 70S initiation complex → stops protein synthesis. Bacteriostatic. Also a weak MAOi (→ serotonin syndrome risk).
VRE	✗ No	✓ Yes
Lung penetration	Poor (~25%)	Excellent (~100%) -key advantage in pneumonia
Renal dosing	Yes -trough/AUC monitoring required	No adjustment needed
Max duration	No hard limit	≤ 14 days (thrombocytopenia risk)
Key toxicity	Nephrotoxicity, Red Man Syndrome, ototoxicity	Thrombocytopenia (> 14d), serotonin syndrome (MAOi), lactic acidosis, peripheral neuropathy (may be irreversible), optic neuritis (> 28d), myelosuppression

🏆 Vancomycin Wins

MRSA bacteremia / endocarditis
Osteomyelitis (long-duration OK)
Default empiric MRSA coverage
Patient on SSRIs (serotonin risk with linezolid)

🏆 Linezolid Wins

MRSA pneumonia (superior lung penetration) ZEPHyR, 2012
VRE infections
CKD / AKI (no renal adjustment)
No IV access / outpatient Tx (PO = IV)

🧫 Toxin Suppression -Linezolid & Clindamycin: Both inhibit the 50S ribosome → suppress bacterial toxin production. Critical in: necrotizing fasciitis (GAS exotoxins), toxic shock syndrome (TSST-1), PVL-producing MRSA. Vancomycin kills the bug but does NOT stop toxin release. In toxin-mediated disease, always add a protein synthesis inhibitor (clindamycin or linezolid).

⚠️ Linezolid Side Effects to Know: Thrombocytopenia (> 14d -CBC twice weekly), lactic acidosis (weekly lactate if prolonged), peripheral neuropathy & optic neuritis (> 28d -may be irreversible), serotonin syndrome (weak MAOi -avoid with SSRIs/SNRIs/tramadol). If on SSRI → use vancomycin. Never use daptomycin for pneumonia -pulmonary surfactant inactivates it.

📋 Clinical Example -CAP Severity & Antibiotic Choice

Patient: 55M, cough with yellow sputum × 5 days, fever 38.9°C, RR 22, SpO₂ 94% on RA, CXR: RLL consolidation.

Severity -CURB-65: Confusion (0), Urea > 7 mmol/L (0), RR ≥ 30 (0), BP < 90 systolic (0), Age ≥ 65 (0) = Score 0 → outpatient treatment appropriate.

But: SpO₂ 94% borderline + looks unwell → admit for observation.

Inpatient non-ICU CAP:

Ceftriaxone (Rocephin) 1g IV daily + azithromycin (Zithromax) 500mg IV/PO daily
OR levofloxacin (Levaquin) 750mg PO/IV daily (respiratory fluoroquinolone monotherapy -reserve for PCN allergy or failure of beta-lactam)

When to add MRSA coverage (vanc or linezolid): Prior MRSA infection/colonization, cavitary infiltrate, empyema, recent influenza, or severe necrotizing pneumonia. Get nasal MRSA swab -negative PCR has ~95% NPV for MRSA pneumonia → can safely withhold MRSA coverage.

Duration: 5 days total if afebrile ≥ 48h and ≤ 1 sign of clinical instability (CAP-START trial). No need for 7–14 days.

IV → PO switch: Once afebrile, tolerating PO, and clinically improving → switch to oral and discharge. Do not keep patients NPO or on IV abx waiting for "completion of course."

🔄 Updated Practice: Old teaching: treat CAP for 7–14 days. Current evidence: 5 days is sufficient if patient is afebrile ≥48h and has ≤1 sign of clinical instability. Some data supports even 3 days in select patients. Longer courses increase C. difficile risk, resistance, and side effects without improving cure rates.

When to Add Steroids in Pneumonia UPDATED 2023

Four clinical scenarios where steroids are indicated, each with its own drug, dose, and duration. The newest indication is severe CAP in the ICU (CAPE COD 2023, hydrocortisone cuts 28-day mortality 6.2% vs 11.9%, NNT ~18).

Scenario	Indication	Drug & Dose	Duration	Why
Severe CAP in ICU NEW 2023	Any one of: intubated, HFNC FiO2 ≥ 0.5 with P/F < 300, NIV with P/F < 300, or PSI > 130	Hydrocortisone 200 mg IV daily (50 mg q6h or 8 mg/hr continuous infusion)	8 days if improving on day 4 (P/F > 200, breathing spontaneously, SOFA ≤ baseline). 14 days if not improving. Taper at end.	Dampens dysregulated lung inflammation that drives ARDS and shock in the sickest CAP patients. Older trials in non-severe CAP did not show mortality benefit because inflammation is not the rate-limiting step there. CAPE COD, 2023
PJP / PCP pneumonia	PaO2 < 70 mmHg on room air OR A-a gradient ≥ 35 mmHg. Most often HIV (CD4 < 200), also chemotherapy, transplant, chronic steroid users.	Prednisone 40 mg PO BID days 1-5, then 40 mg daily days 6-10, then 20 mg daily days 11-21	21 days total (overlapping the full TMP-SMX course)	Killing PJP releases organism debris that worsens acute lung injury in the first few days of treatment. Pretreating with steroids blunts the inflammatory surge. Mortality benefit only below the PaO2/A-a thresholds; mild PJP does not benefit. Start with or before the first TMP-SMX dose.
COVID-19 pneumonia	Hospitalized COVID requiring supplemental O2 or higher (HFNC, NIV, intubated, or ECMO)	Dexamethasone 6 mg PO/IV daily	Up to 10 days (or until discharge, whichever is sooner)	Reserve for the inflammatory phase of COVID (~7-10 days into illness) when lungs fail. RECOVERY, 2020. Higher doses (12 mg) tested in COVID-STEROID 2 without significant additional benefit, more side effects. Stick to 6 mg. Do NOT give to COVID patients NOT requiring oxygen (RECOVERY showed potential harm in this subgroup).
Septic shock from pneumonia	Vasopressor-dependent septic shock	Hydrocortisone 200 mg/day IV (50 mg q6h or 8 mg/hr continuous infusion)	Until shock resolves and pressors weaning, typically 5-7 days then taper	Shorter shock duration, modest mortality benefit in some subgroups. ADRENAL, 2018 APROCCHSS, 2018. Surviving Sepsis 2026: conditional recommendation. Overlap with severe CAP: if a patient meets BOTH severe CAP criteria AND is in septic shock, the same hydrocortisone 200 mg/day satisfies both indications.

When NOT to give steroids in pneumonia.

Non-severe CAP (ward-level, not meeting CAPE COD criteria). Older trials showed shorter time to clinical stability but no mortality benefit; risks (hyperglycemia, infection, GI bleed) outweigh benefit. ATS/IDSA 2019 still says no.
Suspected or confirmed influenza pneumonia. Associated with higher mortality in observational data; skip unless another indication exists (asthma exacerbation, septic shock).
Suspected fungal pneumonia, especially aspergillosis. Steroids worsen fungal disease.
Active untreated TB. Will disseminate.
Mild PJP (PaO2 > 70 AND A-a < 35 on room air). No mortality benefit, side effects without upside.
COVID-19 NOT requiring supplemental O2. RECOVERY showed potential harm in this subgroup.

📋 On Rounds

Can you use 5 days of antibiotics for CAP?

Yes. Short-Course CAP Trial, 2016 and ATS/IDSA 2019 guidelines recommend minimum 5 days of antibiotics for CAP, with discontinuation once the patient is clinically stable for 48h (afebrile, HR < 100, RR < 24, SBP > 90, SpO₂ > 90%, able to eat, normal mentation). Longer courses do not improve outcomes and increase antibiotic resistance, C. diff risk, and adverse effects. The old "7–14 day" dogma is outdated.

When do you get blood cultures in pneumonia?

Not for all CAP. ATS/IDSA 2019 recommends cultures for: severe CAP (ICU admission), empiric MRSA or Pseudomonas coverage, prior positive cultures for these organisms, recent hospitalization + IV antibiotics within 90 days. Routine blood cultures in non-severe CAP have < 5% positivity rate and rarely change management. For HAP/VAP: always get blood cultures + respiratory cultures (sputum, endotracheal aspirate, or BAL)

When should you add MRSA coverage (vancomycin or linezolid) to CAP treatment?

MRSA coverage is NOT routine for CAP -add only with specific risk factors: (1) Prior MRSA isolation (respiratory culture, nasal swab), (2) Cavitary infiltrate or necrotizing pneumonia on imaging, (3) Concurrent influenza (post-influenza MRSA pneumonia is classic and rapidly fatal), (4) Severe pneumonia requiring ICU admission + risk factors. MRSA nasal swab (PCR) has high negative predictive value (> 95%)

HAP/VAP: when do you choose pip-tazo over cefepime?

Choose pip-tazo when you need anaerobic coverage -aspiration with lung abscess, empyema, necrotizing pneumonia, poor dentition with indolent course, or suspected intra-abdominal co-infection. Pip-tazo covers Pseudomonas + gram-negatives + anaerobes. Cefepime covers Pseudomonas + gram-negatives but has NO anaerobic activity.

What are the criteria for severe CAP requiring ICU admission?

ATS/IDSA 2019 criteria: 1 major criterion = ICU: (1) septic shock requiring vasopressors, (2) mechanical ventilation. ≥ 3 minor criteria = ICU: RR ≥ 30, PaO₂/FiO₂ ≤ 250, multilobar infiltrates, confusion, BUN ≥ 20, WBC < 4K, platelets < 100K, temperature < 36°C, hypotension requiring aggressive fluid resuscitation. Why it matters: severe CAP gets broader empiric coverage -ceftriaxone + azithromycin + vancomycin (if MRSA risk)

Clinical Examples

📋 Case 1, Standard Inpatient CAP with Short-Course Antibiotics

Patient: 72 y/o F with COPD and HTN, presents with 3 days of productive cough, fever 38.6°C, and dyspnea.

Key findings: RR 24, SpO₂ 91% on RA. CXR: RLL consolidation. WBC 16K, procalcitonin 2.8. CURB-65 = 2 (age + BUN 24). Blood cultures x2 drawn.

Management:

Ceftriaxone 1g IV daily + azithromycin 500 mg IV daily (standard non-ICU inpatient regimen)
Supplemental O₂ to maintain SpO₂ ≥ 92%
Afebrile x48h + improving → transition to PO and discharge
Total duration: 5 days Short-Course CAP Trial, 2016, do not extend for persistent CXR abnormality

Teaching point: The old 7-14 day antibiotic course for CAP is outdated. ATS/IDSA 2019 recommends minimum 5 days, stopping once clinically stable x48h. Longer courses increase C. difficile risk and resistance without improving outcomes.

📋 Case 2, Severe CAP with MRSA Risk

Patient: 58 y/o M with IVDU history, presents with high fever, productive cough with blood-tinged sputum, and hypoxia. Recent hospitalization 6 weeks ago.

Key findings: HR 118, BP 86/52, RR 32, SpO₂ 84% on 15L NRB. CXR: multilobar cavitary infiltrates. WBC 22K, lactate 4.8, procalcitonin 18.2. Intubated for respiratory failure.

Management:

Meets ATS/IDSA major criterion for severe CAP (mechanical ventilation), ICU admission
Ceftriaxone + azithromycin + vancomycin (cavitary lesions + recent hospitalization = MRSA risk)
MRSA nasal swab sent, if negative (NPV > 95%), de-escalate vancomycin at 48h
Blood cultures, sputum culture, Legionella and pneumococcal urine antigens

Teaching point: MRSA nasal swab PCR has > 95% negative predictive value, it is the best antibiotic stewardship tool for de-escalating vancomycin. Cavitary infiltrates, necrotizing pneumonia, and post-influenza pneumonia are classic MRSA scenarios.

📋 Case 3, Aspiration Pneumonia vs Chemical Pneumonitis

Patient: 80 y/o M with advanced dementia and dysphagia, witnessed aspiration during feeding. Develops cough and fever 12h later.

Key findings: Temp 38.2°C, RR 22, SpO₂ 93% on 2L NC. CXR: RLL infiltrate (dependent segment). WBC 13K, procalcitonin 0.4.

Management:

Distinguish aspiration pneumonitis (chemical, sterile) from aspiration pneumonia (bacterial infection)
If symptoms develop > 24-48h after aspiration event with rising WBC/PCT → treat as bacterial aspiration PNA
Antibiotics: ceftriaxone + azithromycin (same as CAP, anaerobes are NOT the primary cause)
Add anaerobic coverage (amp-sulbactam or pip-tazo) ONLY if abscess, empyema, or necrotizing PNA

Teaching point: Chemical pneumonitis (within hours of aspiration, sterile inflammation) does NOT need antibiotics. Bacterial aspiration pneumonia is treated like CAP, the old teaching of routine anaerobic coverage with clindamycin is outdated unless there is abscess or necrotizing disease.

📣 Sample Presentation

One-Liner

"Mrs. Evans is a 72-year-old with COPD presenting with 3 days of productive cough, fever 38.6°C, and dyspnea. CXR: right lower lobe consolidation. WBC 16K, procalcitonin 2.8. CURB-65 score 2 (age + BUN 24). Admitted for CAP."

Key Points to Cover on Rounds

CAP -CURB-65 2 (inpatient). Antibiotics: ceftriaxone 1g IV daily + azithromycin 500 mg IV daily (standard non-ICU inpatient regimen). Blood cultures × 2 drawn (before abx). Sputum culture sent. O₂: 3L NC (SpO₂ 93%). Procalcitonin 2.8 (supports bacterial etiology). No MRSA risk factors -vancomycin not added. Influenza/COVID tested (negative). Response at 48h: afebrile, WBC trending 16→12. Plan: step down to PO (levofloxacin or amox-clav + azithro) when tolerating PO + afebrile ×24h. Total duration: 5 days if stable ×48h Short-Course CAP Trial, 2016. Follow-up CXR in 6-8 weeks (rule out underlying mass).

🧪 Workup

Workup -Pneumonia

History: Cough (productive vs dry), fever/chills, dyspnea, pleuritic chest pain, sick contacts, travel, immunosuppression, recent hospitalization/abx (within 90 days)
Physical exam: Tachypnea, crackles/bronchial breath sounds, dullness to percussion, egophony, tactile fremitus
Labs: CBC, BMP, procalcitonin (guides abx duration), lactate if sepsis concern, blood cultures ×2 (before abx in severe/ICU), sputum culture + Gram stain
Imaging: CXR PA + lateral (infiltrate, consolidation, effusion). CT chest if CXR equivocal or complications suspected
Urine antigens: Legionella (serogroup 1) + S. pneumoniae -order in ICU-level or severe CAP
MRSA nasal swab: NPV > 95% -if negative, can safely de-escalate vanc/linezolid
Procalcitonin: < 0.25 → bacterial unlikely. Serial levels guide antibiotic de-escalation (drop > 80% from peak → safe to stop)

Do NOT delay antibiotics for cultures. In sepsis, every hour of delay increases mortality. Draw cultures → give abx immediately.

💊 Medications

Medications -Pneumonia

Full antibiotic regimens are in the Treatment tab with evidence-based dosing and trial citations. Check Drug Interactions and renal dosing before prescribing.

⚡ Summary

Summary

Outpatient CAP

Healthy: amoxicillin 1g TID × 5 days. Comorbidities: amox-clav + azithromycin, or respiratory FQ (levofloxacin). Avoid FQ for uncomplicated.

Inpatient (non-ICU)

Ceftriaxone 1g IV + azithromycin 500 IV. Alternative: respiratory FQ monotherapy (levofloxacin 750 daily).

ICU CAP

Ceftriaxone + azithromycin + vancomycin (if MRSA risk). MRSA nasal swab: negative = de-escalate vanc (NPV > 95%).

Duration

5 days if: afebrile ≥ 48h, improving, no more than 1 instability criterion Short-Course CAP Trial, 2016. Don't treat longer just because CXR hasn't cleared.

Follow-Up CXR

6-8 weeks post-treatment (rule out underlying malignancy, especially if smoker, age > 50, or slow to resolve).

Aspiration

Chemical pneumonitis (sterile) = NO abx. Bacterial aspiration PNA = treat like CAP (ceftriaxone + azithro). Anaerobes are NOT the primary cause. Add anaerobic coverage (amp-sulbactam, pip-tazo) ONLY if abscess, empyema, or necrotizing PNA.

📄 One Pager

Pulmonology / ID · One Pager

Community-Acquired Pneumonia

Outpatient: amoxicillin (healthy) or amox-clav + azithro (comorbidities). Inpatient: ceftriaxone + azithromycin. ICU: add vanc if MRSA risk. Duration: 5 days if stable × 48h.

🧪 Severity

CURB-65: Confusion, Urea > 20, RR ≥ 30, BP < 90/60, age ≥ 65. 0-1: outpatient. 2: admit. ≥ 3: ICU consideration. ATS/IDSA: 1 major criterion or ≥ 3 minor = ICU.

🚨 Empiric Treatment

Outpatient (healthy): amoxicillin 1g TID × 5d. Outpatient (comorbid): amox-clav + azithro or respiratory FQ. Inpatient (non-ICU): ceftriaxone + azithromycin. ICU: ceftriaxone + azithro ± vancomycin if MRSA risk.

💊 Key Principles

Duration: 5 days if afebrile ≥ 48h + improving Short-Course CAP Trial, 2016. MRSA nasal swab: negative NPV > 95% → de-escalate vancomycin. Follow-up CXR at 6-8 weeks (rule out mass, especially smoker > 50).

💊 Key Drugs

Ceftriaxone1g IV daily

Azithromycin500 mg IV/PO daily

Amoxicillin1g TID (outpatient)

Vancomycin15-20 mg/kg (MRSA risk)

⚠️ Pitfalls

Treating > 5 days without indication (short course is standard)
FQ for uncomplicated outpatient CAP (reserve for comorbidities)
Not getting follow-up CXR at 6-8 weeks in smokers
Forgetting atypical coverage (azithromycin) for inpatient CAP