What are the guidelines for managing Hospital-Acquired Pneumonia (HAP)?

Hospital-Acquired Pneumonia (HAP) Management Guidelines: IDSA/ATS 2016

Definition and Diagnosis

Hospital-acquired pneumonia is defined as pneumonia occurring ≥48 hours after hospitalization in non-intubated patients, diagnosed based on clinical criteria and new/progressive radiographic infiltrates. 1

• Obtain respiratory samples (sputum or lower respiratory tract cultures) before initiating antibiotics to guide targeted therapy and enable subsequent de-escalation 1
• Do not delay antibiotic therapy in critically ill patients while awaiting cultures 1
• Biomarkers should not be used as the primary diagnostic tool 2

Local Antibiogram and Surveillance

All hospitals must regularly generate and disseminate a local antibiogram tailored to their HAP population to guide empiric therapy decisions. 1

• Empiric antibiotic regimens must be based on local pathogen distribution and antimicrobial susceptibilities 1
• The ICU-specific resistance rate (not hospital-wide data) is the relevant factor for treatment decisions 1, 3

Risk Stratification for Empiric Therapy

Low-Risk Patients (No MRSA Risk Factors, Not High Mortality Risk)

For patients without MRSA risk factors and not at high risk of mortality, prescribe monotherapy with activity against methicillin-sensitive S. aureus (MSSA). 1

Low-risk criteria include:

• No prior IV antibiotic use within 90 days 1
• Hospitalization in a unit where <20% of S. aureus isolates are methicillin-resistant 1
• No septic shock 1
• No need for ventilatory support due to HAP 1

Recommended monotherapy options: 1

• Piperacillin-tazobactam 4.5 g IV q6h
• Cefepime 2 g IV q8h
• Levofloxacin 750 mg IV daily
• Imipenem 500 mg IV q6h
• Meropenem 1 g IV q8h

Intermediate-Risk Patients (MRSA Risk Factors Present, Not High Mortality Risk)

For patients with MRSA risk factors but not at high mortality risk, prescribe an antipseudomonal agent PLUS MRSA coverage. 1

MRSA risk factors include: 1

• Prior IV antibiotic use within 90 days
• Hospitalization in a unit where >20% of S. aureus isolates are methicillin-resistant
• Unknown MRSA prevalence in the unit

Antipseudomonal options (choose one): 1

• Piperacillin-tazobactam 4.5 g IV q6h
• Cefepime or ceftazidime 2 g IV q8h
• Levofloxacin 750 mg IV daily
• Ciprofloxacin 400 mg IV q8h
• Imipenem 500 mg IV q6h
• Meropenem 1 g IV q8h
• Aztreonam 2 g IV q8h

PLUS MRSA coverage (choose one): 1

• Vancomycin 15 mg/kg IV q8-12h (target trough 15-20 mg/mL; consider loading dose of 25-30 mg/kg IV × 1 for severe illness)
• Linezolid 600 mg IV q12h

High-Risk Patients (High Mortality Risk or Recent IV Antibiotics)

For patients at high risk of mortality or with IV antibiotic use in the prior 90 days, prescribe TWO antipseudomonal agents (avoiding two β-lactams) PLUS MRSA coverage. 1

High mortality risk factors include: 1

• Need for ventilatory support due to HAP
• Septic shock

Dual antipseudomonal therapy (choose TWO from different classes, avoid two β-lactams): 1

β-lactam options (choose one):

• Piperacillin-tazobactam 4.5 g IV q6h
• Cefepime or ceftazidime 2 g IV q8h
• Imipenem 500 mg IV q6h
• Meropenem 1 g IV q8h
• Aztreonam 2 g IV q8h

Second agent (choose one from a different class):

• Levofloxacin 750 mg IV daily
• Ciprofloxacin 400 mg IV q8h
• Amikacin 15-20 mg/kg IV daily
• Gentamicin 5-7 mg/kg IV daily
• Tobramycin 5-7 mg/kg IV daily

PLUS MRSA coverage: 1

• Vancomycin 15 mg/kg IV q8-12h (target trough 15-20 mg/mL)
• Linezolid 600 mg IV q12h

Special Considerations

Structural Lung Disease

If the patient has structural lung disease increasing risk of gram-negative infection (bronchiectasis or cystic fibrosis), prescribe two antipseudomonal agents regardless of other risk factors. 1

Threshold Rationale

The 10%-20% MRSA threshold and 10% threshold for dual antipseudomonal coverage were chosen to ensure ≥95% of patients receive empiric therapy active against their likely pathogens 1

Individual ICUs may modify these thresholds based on local epidemiology 1

Polymyxins for MDR Pathogens

For multidrug-resistant Pseudomonas when other options are unavailable, colistin may be used (1 million IU = approximately 30 mg colistin base activity = approximately 80 mg colistimethate) 1

Polymyxin B dosing: 1 mg = 10,000 units 1

Aztreonam as Adjunctive Agent

In the absence of other options, aztreonam can be used as an adjunctive agent with another β-lactam because it has different targets within the bacterial cell wall 1

De-escalation and Duration

Tailor antibiotic therapy to susceptibility data of the identified pathogen once microbiological and clinical response data become available (typically by day 3). 1, 2

• The recommended duration for HAP treatment is 7-14 days 2
• Shorter courses (7-8 days) are appropriate for patients with good clinical response 4, 3
• Longer courses may be necessary for immunocompromised patients, complications (lung abscess, empyema, necrotizing pneumonia), or infections with non-fermenting gram-negative bacilli 4, 3

Common Pitfalls

The competing goals of providing early appropriate coverage versus avoiding superfluous treatment require balancing adequate empiric therapy against risks of adverse drug effects, Clostridioides difficile infections, antibiotic resistance, and increased cost. 1

• Inappropriate initial therapy increases mortality, making adequate empiric coverage crucial 4
• Overtreatment with broad-spectrum antibiotics when not indicated contributes to resistance and complications 1
• Third-generation cephalosporins carry higher risk of C. difficile infection compared to penicillins or quinolones 1, 3
• Aminoglycosides should never be used as monotherapy for HAP, even when the isolate appears susceptible 2