Empiric Treatment of Hospital-Acquired Pneumonia (HAP)

General Principles

The Infectious Diseases Society of America recommends that empiric antibiotic therapy for hospital-acquired pneumonia should include coverage for Staphylococcus aureus, Pseudomonas aeruginosa, and other gram-negative bacilli, with specific regimens determined by risk factors for multidrug-resistant pathogens and local antimicrobial susceptibility patterns 1, 2

For patients with early-onset HAP without risk factors for MDR pathogens, in units with low MRSA prevalence, the European Respiratory Society suggests considering narrow-spectrum antibiotics such as ertapenem, ceftriaxone, cefotaxime, moxifloxacin, or levofloxacin 3, 4
Risk factors that warrant broader coverage include prior intravenous antibiotic use within 90 days, high risk for mortality, hospital settings with high rates of MDR pathogens, prolonged hospitalization, and previous colonization with MDR pathogens 2, 3

For HAP with low risk of MDR pathogens, the Infectious Diseases Society of America recommends single agent therapy with MSSA coverage, such as piperacillin-tazobactam, cefepime, levofloxacin, or meropenem 1, 2
For HAP with risk factors for MRSA, the Infectious Diseases Society of America recommends including MRSA coverage with vancomycin or linezolid 1, 2, 5
For HAP with risk factors for MDR gram-negative pathogens, the Infectious Diseases Society of America recommends using two antipseudomonal agents from different classes, such as a β-lactam-based agent and an aminoglycoside or fluoroquinolone 1, 2, 6

Empiric therapy should be guided by local antibiograms specific to the HAP population whenever possible 2
Aminoglycosides should not be used as the sole antipseudomonal agent 6
Initial therapy should be re-evaluated and narrowed based on culture results and clinical response at 72-96 hours 3
Oxacillin, nafcillin, or cefazolin are preferred for confirmed MSSA infections but are not necessary for empiric coverage if one of the recommended agents with MSSA activity is used 2

Using aminoglycosides as monotherapy for HAP is not recommended 6
Not adjusting therapy based on patient-specific risk factors for MDR pathogens can lead to poor outcomes 2, 3
Continuing unnecessarily broad therapy after culture results are available can contribute to antimicrobial resistance 3