Typical duration 5 days with clinical stability criteria
Doxycycline oral
100 mg twice daily
Avoid in pregnancy
Azithromycin oral
Use only if local pneumococcal macrolide resistance low
500 mg day 1
250 mg daily days 2-5
Comorbidities
Amoxicillin clavulanate oral
875 mg 125 mg twice daily
Alternative 2 g 125 mg twice daily extended release if available
Plus azithromycin oral
500 mg day 1
250 mg daily days 2-5
Plus doxycycline oral alternative to macrolide
100 mg twice daily
Cefuroxime oral alternative beta-lactam
500 mg twice daily
Plus azithromycin oral
500 mg day 1
250 mg daily days 2-5
Levofloxacin oral monotherapy
750 mg daily
QT prolongation and tendinopathy risk context
Moxifloxacin oral monotherapy
400 mg daily
Avoid with significant QT risk
Inpatient non-ICU regimens
Beta-lactam plus macrolide
Ceftriaxone IV
1-2 g daily
Plus azithromycin IV or oral
500 mg daily
Ampicillin sulbactam IV
1.5-3 g every 6 hours
Plus azithromycin IV or oral
500 mg daily
Beta-lactam plus doxycycline alternative
Ceftriaxone IV
1-2 g daily
Plus doxycycline IV or oral
100 mg twice daily
Respiratory fluoroquinolone monotherapy
Levofloxacin IV or oral
750 mg daily
Moxifloxacin IV or oral
400 mg daily
ICU regimens
Beta-lactam plus macrolide
Ceftriaxone IV
2 g daily
Plus azithromycin IV
500 mg daily
Cefotaxime IV alternative
2 g every 8 hours
Plus azithromycin IV
500 mg daily
Beta-lactam plus fluoroquinolone alternative
Ceftriaxone IV
2 g daily
Plus levofloxacin IV
750 mg daily
MRSA coverage when indicated
Vancomycin IV
15-20 mg/kg per dose
Typical interval every 8-12 hours based on renal function
AUC-guided monitoring per local protocol
Linezolid IV or oral
600 mg twice daily
Thrombocytopenia risk with prolonged therapy
Pseudomonas coverage when indicated
Cefepime IV
2 g every 8 hours
Piperacillin tazobactam IV
4.5 g every 6 hours
Meropenem IV
1 g every 8 hours
Plus azithromycin IV
500 mg daily
Plus levofloxacin IV alternative
750 mg daily
Timing, duration, and de-escalation
Antimicrobial stewardship
Early administration
Severe CAP or shock within 1 hour
Nonsevere CAP without shock within 3 hours
De-escalation strategy
Narrow to identified pathogen and susceptibilities
Stop MRSA or Pseudomonas agents if risk low and tests negative
Negative MRSA nasal PCR supports stopping anti-MRSA in many settings
Duration guidance
Minimum 5 days for most uncomplicated CAP
Clinical stability criteria for stop
Afebrile 48-72 hours
HR <= 100 per minute
RR <= 24 per minute
SBP >= 90 mmHg
SpO2 >= 90% or PaO2 >= 60 mmHg on room air or baseline
Normal mental status baseline
Oral intake adequate
Extended duration triggers
MRSA pneumonia
Pseudomonas pneumonia
Lung abscess or necrotizing pneumonia
Empyema
Supportive care
Respiratory support
Oxygen therapy
Nasal cannula escalation to face mask based on SpO2 targets
HFNC for high oxygen requirement with tachypnea
NIV for COPD with hypercapnia and acidosis when appropriate
Bronchodilators for reactive component
Salbutamol inhaled
4-8 puffs MDI with spacer every 20 minutes for 1 hour as needed
Nebulized alternative per local protocol
Fluids and hemodynamics
Crystalloid resuscitation for hypoperfusion
Balanced crystalloids preferred by many protocols
Reassess after each bolus
Vasopressors for persistent hypotension
Norepinephrine infusion
Start 0.05-0.1 micrograms/kg/min
Titrate every 2-5 minutes to MAP >= 65 mmHg
Typical ceiling individualized by response and adverse effects
Vasopressin adjunct
0.03 units/min fixed dose for refractory shock
Fever and pain control
Acetaminophen oral or IV
650-1000 mg every 6 hours as needed
Maximum 3000 mg per day typical conservative limit
NSAID use individualized
Renal and GI risk context
Adjunctive therapies
Corticosteroids
Not routine for nonsevere CAP
Consider for refractory septic shock
Hydrocortisone IV
50 mg every 6 hours
COPD exacerbation overlap
Prednisone oral
40 mg daily for 5 days
Pleural space management
Diagnostic thoracentesis for moderate or large effusion
pH and glucose and LDH pleural analysis per protocol
Empyema management
Early drainage plus antibiotics
Surgical consultation for loculated disease
Special Populations
Pregnancy
Pregnancy considerations
Physiologic changes
Lower PaCO2 baseline
Reduced functional residual capacity
Antibiotic safety
Beta-lactams generally preferred
Azithromycin generally acceptable
Avoid doxycycline
Fluoroquinolones generally avoided unless no alternatives
Imaging considerations
Chest radiograph with abdominal shielding when possible
CT when benefits outweigh risks
Maternal oxygenation priority
Maintain SpO2 >= 95% when possible to support fetal oxygenation
Geriatric
Older adult considerations
Atypical presentation
Delirium
Falls
Minimal fever
Higher complication risk
Dehydration and AKI
Delirium with hypoxemia
Medication risks
QT prolongation vulnerability
C difficile risk with broad antibiotics
Disposition caution
Lower threshold for admission with frailty or limited supports
Pediatrics
Pediatric considerations
Etiology differences
Viral predominance in many age groups
Pneumococcal disease in unvaccinated or high-risk
Admission triggers
Hypoxemia
Dehydration
Apnea or grunting in infants
Caregiver inability to manage at home
Antibiotic selection
Amoxicillin weight-based for suspected typical bacterial CAP
80-90 mg/kg/day divided twice daily
Maximum per local pediatric dosing limits
Macrolide for suspected atypical pathogens in older children
Azithromycin weight-based per protocol
Imaging minimization
Chest radiograph for moderate to severe or uncertain diagnosis
Avoid CT unless complications suspected
Background
Epidemiology
Disease burden
CAP common cause of hospitalization and mortality in adults
Higher rates in older adults and comorbid disease
Common pathogens
Streptococcus pneumoniae
Respiratory viruses
Atypical pathogens
Mycoplasma pneumoniae
Chlamydophila pneumoniae
Legionella species
Risk groups for resistant pathogens
Recent healthcare exposure
Prior MRSA or Pseudomonas colonization
Pathophysiology
Mechanisms
Microaspiration and impaired host defenses
Smoking and COPD as defense impairment
Alveolar inflammation and consolidation
VQ mismatch driving hypoxemia
Systemic inflammatory response
Sepsis and shock pathways
Complications
Parapneumonic effusion and empyema
Necrotizing pneumonia
Lung abscess
Therapeutic Considerations
Treatment rationale
Early appropriate antibiotics improve outcomes in severe CAP
Timing most critical in shock
Beta-lactam plus macrolide in severe CAP
Coverage of typical and atypical pathogens
Potential immunomodulatory benefit of macrolides
De-escalation reduces harm
Lower C difficile risk
Lower resistance pressure
Short-course therapy efficacy
5-day minimum in uncomplicated cases with stability
Patient Discharge Instructions
copy discharge instructions
Home care plan
Antibiotics exactly as prescribed
Do not stop early unless directed
Fluids and rest
Aim for light activity as tolerated
Fever control
Acetaminophen as needed within safe daily maximum
Smoking and vaping avoidance
Avoid until fully recovered
Expected recovery
Fever improvement often within 48-72 hours after antibiotics
Cough and fatigue can persist for weeks
Return to ED now
Trouble breathing
Blue lips or severe chest pain
Fainting or confusion
Persistent vomiting or inability to keep fluids down
Worsening fever after 48-72 hours on antibiotics
Oxygen saturation below target if home pulse oximeter available
Follow-up
Primary care follow-up in 24-72 hours if symptoms moderate
Earlier follow-up for older adults or significant comorbidities
Repeat chest imaging if symptoms not improving or risk factors for malignancy
References
Clinical guidelines and evidence sources
Guideline sources
ATS and IDSA guideline for adult CAP
Severity criteria and empiric regimen recommendations
Surviving Sepsis Campaign guidelines
Shock resuscitation targets and vasopressor strategy
National guidance for antimicrobial stewardship
Duration and de-escalation principles
Local antibiogram integration
Macrolide resistance thresholds for outpatient monotherapy
Coding and terminology
Coding references
ICD-10 CAP unspecified organism
J18.9
ICD-10 pneumococcal pneumonia
J13
ICD-10 pneumonia due to influenza virus
J10.0
SNOMED CT concept alignment
Community acquired pneumonia concept mapping per local terminology service
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.