What are the recommended guidelines for assessing and treating community‑acquired pneumonia in an elderly patient (≥65 years), including severity assessment, outpatient versus inpatient antibiotic choices, supportive care, and vaccination?

Community-Acquired Pneumonia in the Elderly: Assessment and Treatment Guidelines

Severity Assessment and Site-of-Care Decision

Use the CURB-65 score (Confusion, Urea >7 mmol/L, Respiratory rate ≥30, Blood pressure <90/60, age ≥65) or Pneumonia Severity Index (PSI) to determine hospitalization need; elderly patients with CURB-65 ≥2 or PSI class IV-V require admission, while those with CURB-65 0-1 or PSI I-III can be managed outpatient if no other concerning features exist. 1

• Assess for ICU admission criteria: septic shock requiring vasopressors, respiratory failure requiring mechanical ventilation, or ≥3 minor criteria (respiratory rate >30/min, PaO2/FiO2 <250, multilobar infiltrates, confusion, uremia, leukopenia, thrombocytopenia, hypothermia, hypotension requiring aggressive fluid resuscitation) 1

• Elderly patients may present atypically with altered mental status, functional decline, or absence of fever rather than classic symptoms of cough, fever, and dyspnea 2, 3

• Obtain chest radiograph to confirm infiltrate; multilobar involvement mandates admission regardless of other criteria 4, 1

• Pulse oximetry showing SpO2 <92% on room air requires hospitalization 1

Outpatient Antibiotic Treatment (PSI I-III, CURB-65 0-1)

Previously Healthy Elderly Without Comorbidities

Amoxicillin 1 g orally three times daily for 5-7 days is the preferred first-line therapy, providing superior coverage against Streptococcus pneumoniae including many drug-resistant strains. 1, 5

• Doxycycline 100 mg orally twice daily for 5-7 days is an acceptable alternative 1

• Macrolides (azithromycin 500 mg day 1, then 250 mg daily days 2-5; or clarithromycin 500 mg twice daily) should only be used in areas where pneumococcal macrolide resistance is documented <25% 1

Elderly with Comorbidities (COPD, diabetes, heart/liver/renal disease, malignancy)

Combination therapy with amoxicillin-clavulanate 875/125 mg twice daily PLUS azithromycin (500 mg day 1, then 250 mg daily) OR doxycycline 100 mg twice daily for 5-7 days provides coverage of both typical and atypical pathogens. 1, 2

• Alternative: respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily OR moxifloxacin 400 mg daily) for 5-7 days, though reserve for penicillin allergy or macrolide contraindication due to FDA warnings about serious adverse events in elderly 1

Inpatient Non-ICU Antibiotic Treatment

Ceftriaxone 1-2 g IV daily PLUS azithromycin 500 mg daily (IV or oral) is the standard regimen for hospitalized elderly patients, providing comprehensive coverage with strong evidence for mortality reduction. 1, 2

• Alternative β-lactams: cefotaxime 1-2 g IV every 8 hours OR ampicillin-sulbactam 3 g IV every 6 hours, always combined with azithromycin 1

• Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg IV daily OR moxifloxacin 400 mg IV daily) is equally effective but reserve for penicillin-allergic patients 1

• Administer first antibiotic dose in the emergency department immediately; delays beyond 8 hours increase 30-day mortality by 20-30% 1, 2

Severe CAP Requiring ICU Admission

Combination therapy is mandatory: ceftriaxone 2 g IV daily PLUS azithromycin 500 mg IV daily OR a respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily); monotherapy is inadequate and associated with higher mortality. 1

• For penicillin-allergic ICU patients: aztreonam 2 g IV every 8 hours PLUS levofloxacin 750 mg IV daily 1

Add Antipseudomonal Coverage ONLY if Risk Factors Present:

• Structural lung disease (bronchiectasis, cystic fibrosis), recent hospitalization with IV antibiotics within 90 days, or prior respiratory isolation of Pseudomonas aeruginosa 1

• Regimen: piperacillin-tazobactam 4.5 g IV every 6 hours OR cefepime 2 g IV every 8 hours PLUS ciprofloxacin 400 mg IV every 8 hours OR levofloxacin 750 mg IV daily PLUS aminoglycoside (gentamicin or tobramycin 5-7 mg/kg IV daily) 1

Add MRSA Coverage ONLY if Risk Factors Present:

• Prior MRSA infection/colonization, recent hospitalization with IV antibiotics, post-influenza pneumonia, or cavitary infiltrates on imaging 1

• Regimen: vancomycin 15 mg/kg IV every 8-12 hours (target trough 15-20 µg/mL) OR linezolid 600 mg IV every 12 hours, added to base regimen 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 (temperature ≤37.8°C, heart rate ≤100, respiratory rate ≤24, systolic BP ≥90 mmHg, oxygen saturation ≥90% on room air, ability to maintain oral intake, normal mental status). 1, 2

• Typical duration for uncomplicated CAP: 5-7 days 1, 6

• Extended duration of 14-21 days required for Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli 1, 3

• For severe microbiologically undefined pneumonia: 10 days 1

Transition from IV to Oral Therapy

Switch to oral antibiotics when the patient is hemodynamically stable (systolic BP ≥90 mmHg, heart rate ≤100), clinically improving, afebrile for 48-72 hours, able to take oral medications, and has oxygen saturation ≥90% on room air—typically achievable by hospital day 2-3. 1, 2

• Oral step-down options: amoxicillin 1 g three times daily PLUS azithromycin 500 mg daily, OR amoxicillin-clavulanate 875/125 mg twice daily PLUS azithromycin, OR continue respiratory fluoroquinolone 1

Supportive Care

• Oxygen therapy targeting PaO2 >8 kPa (60 mmHg) and SpO2 >92%; use high-flow oxygen as needed in uncomplicated pneumonia 1

• For COPD patients with ventilatory failure, guide oxygen by repeated arterial blood gases to avoid CO2 retention 1

• Assess and correct volume depletion with IV fluids 1

• Monitor temperature, respiratory rate, pulse, blood pressure, mental status, and oxygen saturation at least twice daily 1

Management of Treatment Failure

If no clinical improvement by day 2-3, obtain repeat chest radiograph, CRP, white blood cell count, and additional microbiological specimens; consider chest CT to evaluate for complications (pleural effusion, lung abscess, central airway obstruction). 1

• For non-severe pneumonia initially 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

Diagnostic Testing

• Obtain blood cultures and sputum Gram stain/culture before initiating antibiotics in ALL hospitalized elderly patients to enable pathogen-directed therapy 1, 2

• Urinary antigen testing for Legionella pneumophila serogroup 1 should be considered in severe CAP or ICU patients 1

• Chest radiograph not required before hospital discharge if satisfactory clinical recovery, but arrange at 6 weeks for patients with persistent symptoms, physical signs, or high risk for underlying malignancy (smokers, age >50 years) 1

Vaccination and Prevention

All adults ≥65 years should receive the 20-valent pneumococcal conjugate vaccine alone OR the 15-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine one year later. 1, 6

• Annual influenza vaccination for all elderly patients 1, 2, 6

• Smoking cessation counseling for all current smokers 1, 2

• Nutritional support and lifestyle modifications to prevent pneumonia 2

Critical Pitfalls to Avoid

• Never use macrolide monotherapy in hospitalized elderly patients; it provides inadequate coverage for typical bacterial pathogens like S. pneumoniae 1

• Avoid macrolide use in areas where pneumococcal macrolide resistance exceeds 25% 1, 6

• Do not delay antibiotic administration beyond 8 hours in hospitalized patients; this increases 30-day mortality by 20-30% 1, 2

• Do not add broad-spectrum antipseudomonal or MRSA coverage automatically; restrict to patients with documented risk factors to prevent resistance and adverse effects 1

• Avoid indiscriminate fluoroquinolone use in elderly due to FDA warnings about tendon rupture, peripheral neuropathy, aortic dissection, and rising resistance 1

• Do not extend therapy beyond 7-8 days in responding patients without specific indications; longer courses increase antimicrobial resistance risk without improving outcomes 1