What is the recommended treatment for a patient presenting with pneumonia?

Treatment of Community-Acquired Pneumonia

For hospitalized patients with community-acquired pneumonia, administer ceftriaxone 1-2 g IV daily plus azithromycin 500 mg daily immediately upon diagnosis, as delayed antibiotic administration beyond 8 hours increases 30-day mortality by 20-30%. 1

Outpatient Treatment (Non-Hospitalized Patients)

For previously healthy adults without comorbidities:

• Amoxicillin 1 g orally three times daily for 5-7 days is the preferred first-line therapy 1
• Doxycycline 100 mg orally twice daily serves as an acceptable alternative 1
• Avoid macrolide monotherapy (azithromycin, clarithromycin) unless local pneumococcal macrolide resistance is documented <25% 1, 2

For patients with comorbidities (COPD, diabetes, heart/liver/renal disease, malignancy, or recent antibiotic use within 3 months):

• Combination therapy: Amoxicillin-clavulanate 875/125 mg orally twice daily PLUS azithromycin 500 mg day 1, then 250 mg daily for days 2-5 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily OR moxifloxacin 400 mg daily) 1

Inpatient Treatment (Non-ICU Hospitalized Patients)

Two equally effective regimens exist with strong evidence:

1. β-lactam plus macrolide combination (preferred):

   • Ceftriaxone 1-2 g IV daily PLUS azithromycin 500 mg daily 1, 3
   • Alternative β-lactams: Cefotaxime 1-2 g IV every 8 hours OR ampicillin-sulbactam 3 g IV every 6 hours 1

2. Respiratory fluoroquinolone monotherapy:

   • Levofloxacin 750 mg IV daily OR moxifloxacin 400 mg IV daily 1
   • Use for penicillin-allergic patients 1

Administer the first antibiotic dose in the emergency department immediately—do not wait for admission to the floor. 1

Severe Pneumonia (ICU-Level Care)

Combination therapy is mandatory for all ICU patients—monotherapy is inadequate:

• Ceftriaxone 2 g IV daily (or cefotaxime 1-2 g IV every 8 hours) PLUS azithromycin 500 mg IV daily 1
• Alternative: β-lactam PLUS respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) 1

Add antipseudomonal coverage if risk factors present:

• Risk factors: Structural lung disease (bronchiectasis), recent hospitalization with IV antibiotics within 90 days, prior Pseudomonas aeruginosa isolation 1
• Regimen: Antipseudomonal β-lactam (piperacillin-tazobactam 4.5 g IV every 6 hours, cefepime 2 g IV every 8 hours, imipenem, or meropenem) PLUS ciprofloxacin 400 mg IV every 8 hours OR levofloxacin 750 mg IV daily PLUS aminoglycoside (gentamicin 5-7 mg/kg IV daily) 1

Add MRSA coverage if risk factors present:

• Risk factors: Prior MRSA infection/colonization, recent hospitalization with IV antibiotics, post-influenza pneumonia, cavitary infiltrates on imaging 1
• Regimen: Add vancomycin 15 mg/kg IV every 8-12 hours (target trough 15-20 mg/mL) OR linezolid 600 mg IV every 12 hours 1

Duration of Therapy

Treat for a minimum of 5 days AND until the patient is afebrile for 48-72 hours with no more than one sign of clinical instability:

• Typical duration for uncomplicated CAP: 5-7 days 1, 4, 3
• Extended duration (14-21 days) required for: Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli 1
• Do not extend therapy beyond 7 days in responding patients without specific indications, as this increases antimicrobial resistance risk 1

Transition from IV to Oral Therapy

Switch from IV to oral antibiotics when ALL of the following criteria are met:

• Hemodynamically stable (no vasopressor requirement) 1
• Clinically improving (decreased respiratory rate, decreased oxygen requirement) 1
• Afebrile for 48-72 hours 1
• Able to take oral medications 1
• Normal gastrointestinal function 1

Typical timing: Day 2-3 of hospitalization 1

Oral step-down options:

• Amoxicillin 1 g orally three times daily PLUS azithromycin 500 mg orally daily 1
• Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg orally daily or moxifloxacin 400 mg orally daily) 1

Critical Pitfalls to Avoid

Never use macrolide monotherapy (azithromycin alone) in hospitalized patients—it provides inadequate coverage for typical bacterial pathogens like S. pneumoniae. 1

Never delay antibiotic administration beyond 8 hours in hospitalized patients—this increases 30-day mortality by 20-30%. 1

Never use macrolides in areas where pneumococcal macrolide resistance exceeds 25%—this leads to treatment failure. 1

Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient CAP due to FDA warnings about serious adverse events (tendon rupture, peripheral neuropathy, QT prolongation) and resistance concerns. 1, 2

Do not automatically escalate to broad-spectrum antibiotics (antipseudomonal or anti-MRSA coverage) without documented risk factors—this promotes resistance. 1

Diagnostic Testing for Hospitalized Patients

Obtain BEFORE initiating antibiotics:

• Blood cultures (two sets from separate sites) 1
• Sputum Gram stain and culture (if patient can produce adequate sample) 1
• Urinary antigen testing for Legionella pneumophila serogroup 1 (in severe CAP or ICU patients) 1
• COVID-19 and influenza testing when these viruses are circulating in the community 3

Follow-Up

For outpatients:

• Clinical review at 48 hours or sooner if clinically worsening 5, 1

For all hospitalized patients:

• Chest radiograph NOT required before hospital discharge if satisfactory clinical recovery 5, 4
• Schedule clinical review at 6 weeks with general practitioner or hospital clinic 5, 4
• Obtain chest radiograph at 6 weeks ONLY for: persistent symptoms, persistent physical signs, smokers, or age >50 years (to exclude underlying malignancy) 5, 1

Special Populations

Elderly or debilitated patients:

• Lower threshold for hospitalization 1
• Consider combination therapy even if otherwise would be treated as outpatient 5

Penicillin-allergic patients:

• Respiratory fluoroquinolone (levofloxacin or moxifloxacin) for all settings 1
• For ICU patients: Aztreonam 2 g IV every 8 hours PLUS respiratory fluoroquinolone 1

Patients with COPD or structural lung disease:

• Require combination therapy even in outpatient setting due to increased risk of Pseudomonas aeruginosa 1

Failure to Improve by Day 2-3

If no clinical improvement by 48-72 hours:

• Obtain repeat chest radiograph, CRP, white blood cell count 1
• Obtain additional microbiological specimens (blood cultures, sputum culture) 1
• Consider chest CT to reveal unsuspected pleural effusions, lung abscess, or central airway obstruction 1
• For non-severe pneumonia on amoxicillin monotherapy: Add or substitute a macrolide 1
• For non-severe pneumonia on combination therapy: Switch to respiratory fluoroquinolone 1
• For severe pneumonia not responding to combination therapy: Consider adding rifampicin 1