Antibiotic prescribing for hospital-acquired pneumonia (HAP)

This note shows when and how to prescribe antibiotic for hospital-acquired pneumonia (HAP). And which antibiotic should be prescribed.

How to diagnose

Patients hospital-acquired pneumonia with may present with fever or change in respiratory symptoms, secretions, oxygen needs and mental status. Diagnosis may be confirmed by imaging criteria or criteria based on signs and symptoms.

Diagnosis based on imaging requires ≥ 2 serial chest x-rays with new and persistent or progressive and persistent infiltrate, consolidation, or cavitation plus 1 definitive chest x-ray is acceptable in patients without underlying pulmonary or cardiac disease.

Table (1). Diagnosis of Hospital acquired pneumonia
Diagnosis based on signs and symptoms requires ≥ 1 of 3 clinical criteria plus ≥ 2 of 4 pulmonary criteria...
Clinical criteria include
Fever > 38 degrees C (100.4 degrees F) Leukopenia (< 4,000 white blood cells/mm3) or leukocytosis (≥ 12,000 white blood cells/mm3) For adults ≥ 70 years old, altered mental status with no other recognized cause
Pulmonary criteria include
New-onset purulent sputum or change in character of sputum or increased respiratory secretions or increased suctioning requirements New-onset or worsening cough, dyspnea, or tachypnea Rales or bronchial breath sounds Worsening gas exchange, such as oxygen desaturations, increased oxygen requirements or increased ventilator demand

When to investigate

Obtain a complete blood count (CBC) with differential, basic metabolic panel, chest x-ray (if not already obtained), lower respiratory tract samples for Gram stain and culture, and blood cultures

Additional tests to consider include blood gas analysis if there is a concern for an impending respiratory failure, urinary antigen testing if Streptococcus pneumoniae or Legionella infection is suspected, respiratory virus PCR and computed tomography if underlying lung pathology (for example bronchiectasis or obstructing neoplasm) or complications (such as empyema or lung abscess) suspected.

Antibiotic prescribing

Empiric antibiotic therapy

Empiric regimen should target Staphylococcus aureus and Pseudomonas aeruginosa and other gram-negative bacteria. Select agent active against methicillin-resistant S. aureus (MRSA) only if ≥ 1 of the following..

IV antibiotic use in the last 90 days,
Hospitalization in a unit with > 20% MRSA prevalence,
Unknown MRSA prevalence.

For patients at low risk for mortality, treat with an agent that targets both methicillin-susceptible S. aureus (MSSA) and gram-negative bacteria, such as piperacillin-tazobactam 4.5 g IV every 6 hours, cefepime 2 g IV every 8 hours, meropenem 1 g IV every 8 hours or imipenem 500 mg IV every 6 hours. Quinolones can be prescribed like levofloxacin 750 mg IV every 24 hours. If risk factors for MRSA are present, add vancomycin 15 mg/kg IV every 8-12 hours and consider one time loading dose of 25-30 mg/kg in patients with severe illness. Adjust dose to target trough levels of 15-20 mg/mL. OR linezolid 600 mg IV every 12 hours.

For patients at high risk of mortality or who have received IV antibiotics in the past 90 days, structural lung disease associated with increased risk of gram-negative infection, such as bronchiectasis or cystic fibrosis or patient is at high risk of mortality due to septic shock and/or need for ventilatory support due to pneumonia, OR who have other risk factors for Pseudomonas infection or multidrug resistant pathogens, use a 3 drug regimen, consider using 2 agents (from different classes) that target Pseudomonas aeruginosa and other gram-negative bacteria as well as one agent effective against MRSA (for MRSA coverage add one of vancomycin or linezolid, "doses mentioned above"). Anti-pseudomonal coverage include beta-lactam/beta-lactam-like piperacillin-tazobactam 4.5 g IV every 6 hours, cefepime or ceftazidime 2 g IV every 8 hours, imipenem 500 mg IV every 6 hours or meropenem 1 g IV every 8 hours. Aztreonam can be used by dose 2 g IV every 8 hours. OR non-beta-lactams like levofloxacin 750 mg IV every 24 hours or ciprofloxacin 400 mg IV every 8 hours. Aminoglycoside such as amikacin 15–20 mg/kg IV daily or tobramycin 5–7 mg/kg IV daily

For HAP due to carbapenem-resistant organisms that are sensitive only to polymyxins, give intravenous polymyxin (colistin or polymyxin B). Colistin dose 5 mg/kg IV × 1 (loading dose) followed by 2.5 mg × (1.5 × CrCl + 30) IV daily, divided q12h (maintenance dose).

For HAP due to Acinetobacter species ― If isolate is susceptible, choose either a carbapenem or ampicillin/sulbactam. If isolate is susceptible only to polymyxins, give intravenous polymyxin (colistin or polymyxin B) and consider adjunctive inhaled colistin. If isolate is susceptible only to colistin, do not use adjunctive rifampicin. Colistin dose 5 mg/kg IV × 1 (loading dose) followed by 2.5 mg × (1.5 × CrCl + 30) IV daily, divided q12h (maintenance dose). Do not use tigecycline. Definitive therapy should be directed by results of antibiotic susceptibility testing. Antimicrobial treatment duration should be 7 days for most patients.

Table (2). ATS/IDSA Recommendations for Empiric Therapy for Hospital-Acquired Pneumonia in Adults
Patient Characteristics	Recommended Therapy
No known risk factors for multidrug-resistant pathogens, early-onset, and any disease severity	1 of the following Ceftriaxone Levofloxacin, moxifloxacin, or ciprofloxacin Ampicillin/sulbactam Ertapenem
Late-onset disease or risk factors for multidrug-resistant pathogens and all disease severity	Combination IV therapy 1 of the following Antipseudomonal cephalosporin (cefepime 1-2 g every 8-12 hours, ceftazidime 2 g every 8 hours) Antipseudomonal carbapenem (imipenem 500 mg every 6 hours or 1 g every 8 hours, or meropenem 1 g every 8 hours) Beta-lactam/beta-lactamase inhibitor (piperacillin-tazobactam 4.5 g every 6 hours) PLUS 1 of Antipseudomonal fluoroquinolone (ciprofloxacin 400 mg every 8 hours or levofloxacin 700 mg/day) Aminoglycoside (amikacin 20 mg/kg/day, gentamycin 7 mg/kg/day, or tobramycin 7 mg/kg/day) If MRSA infection, ADD linezolid 600 mg every 12 hours, or vancomycin 15 mg/kg every 12 hours

References

Wu H, Harder C, Culley C. The 2016 Clinical Practice Guidelines for Management of Hospital-Acquired and Ventilator-Associated Pneumonia. Can J Hosp Pharm. 2017;70(3):251-252.
Kalil AC, Metersky ML, Klompas M, et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;63(5):e61-e111.