What is the best initial treatment of an adult patient with healthcare-associated pneumonia?
Case
A 68-year-old man with hypertension, diabetes, and recent hip fracture with poor functional status presents from a nursing home with a productive cough, shortness of breath, and chills of two-day duration. He finished a five-day course of cephalexin for a urinary tract infection one week ago. His vital signs reveal a blood pressure of 162/80 mm/Hg, temperature of 101.9°F, respirations of 26 breaths per minute, and oxygen saturation of 88% on room air. Coarse breath sounds are noted in the right lung field and his chest X-ray reveals a right-middle-lobe infiltrate.
He is admitted to the hospital with a diagnosis of healthcare-associated pneumonia. What is the best empiric antibiotic coverage for this patient?
Overview
Modern medicine exists over a continuum of care that is delivered in a manifold of different settings. Patients routinely receive complex medical care at home, including wound care and infusion of intravenous antibiotics. Additionally, many patients are interfacing with the healthcare system on a regular basis via hemodialysis centers or sub-acute rehabilitation centers. As a result of these interactions, patients are exposed to—and colonized by—different bacterial pathogens that can result in a variety of infections.1
While patients with healthcare-associated pneumonia (HCAP) can present similarly to those with community-acquired pneumonia (CAP)—patients with CAP normally present with a lower-respiratory-tract infection—the differences in the likely etiological pathogens dictate that these patients be considered for broader-spectrum empiric antibiotics. Hospitalists will continue to be responsible for choosing the initial antibiotic regimen for these patients, and they need to be able to recognize this disease process in order to treat it appropriately.
The joint American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) guidelines released in 2005 emphasize that certain clinical HCAP risk factors center on increased interactions and encounters with healthcare facilities.2 These risk factors are evolving over time to include a patient’s functional status, recent antibiotic use, and clinical severity.
Review of the Data
Differences between HCAP and CAP
HCAP represents a diagnostic category of pneumonia created to differentiate patients with infections caused by a different microbiological subset of bacteria, including possible multi-drug-resistant (MDR) organisms, from patients with CAP. Thus far, culture data support this dichotomy.3,4
Kollef and colleagues performed a multicenter, retrospective cohort study of 4,543 patients with bacterial respiratory culture-positive pneumonia between 2002 and 2003. The study examined the bacteriological differences between CAP and HCAP. In this study, HCAP patients were defined as having: transfer from another healthcare facility; long-term hemodialysis; or prior hospitalization within 30 days in which they had non-ventilator-associated pneumonia (VAP). CAP patients were defined as having non-VAP and non-HCAP.
The study showed that the frequency of Pseudomonas aeurginosa (25% HCAP vs. 17% CAP) and Staphylococcus aureus (46% vs. 25%), which included methicillin-resistant Staphylococcus aureus (MRSA) (18% vs. 6%), was significantly higher in patients with HCAP than those with CAP. Additionally, frequency of Streptococcus pneumoniae (5% vs. 16%) and Haemophilus influenza (5% vs. 16%) infections were noted as significantly lower.3
