What is the proper duration of antibiotic treatment in adults hospitalized with community-acquired pneumonia?
Case
An 83-year-old male with hypertension, coronary artery disease, and obstructive sleep apnea presents with progressive shortness of breath, a productive cough, wheezing, and tachypnea. His blood pressure is 158/70 mm/Hg; temperature is 101.8; respirations are 26 breaths per minute; and oxygen saturation is 87% on room air. He has coarse breath sounds bilaterally, and decreased breath sounds over the right lower lung fields. His chest X-ray reveals a right lower lobe infiltrate. He is admitted to the hospital with a diagnosis of community-acquired pneumonia (CAP), and medical therapy is started. How should his antibiotic treatment be managed?
Overview
Community-acquired pneumonia is the most common infection-related cause of death in the U.S., and the eighth-leading cause of mortality overall.1 According to a 2006 survey, CAP results in more than 1.2 million hospital admissions annually, with an average length of stay of 5.1 days.2 Though less than 20% of CAP patients require hospitalization, cases necessitating admission contribute to more than 90% of the overall cost of pneumonia care.3
During the past several years, the availability of new antibiotics and the evolution of microbial resistance patterns have changed CAP treatment strategies. Furthermore, the development of prognostic scoring systems and increasing pressure to streamline resource utilization while improving quality of care have led to new treatment considerations, such as managing low-risk cases as outpatients.
More recently, attention has been directed to the optimal duration of antibiotic treatment, with a focus on shortening the duration of therapy. Historically, CAP treatment duration has been variable and not evidence-based. Shortening the course of antibiotics might limit antibiotic resistance, decrease costs, and improve patient adherence and tolerability.4 However, before defining the appropriate antibiotic duration for a patient hospitalized with CAP, other factors must be considered, such as the choice of empiric antibiotics, the patient’s initial response to treatment, severity of the disease, and presence of co-morbidities.
Review of the Data
Antibiotic choice. The most widely referenced practice guidelines for the management of CAP patients were published in 2007 by representatives of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS).5 Table 1 (above, right) summarizes the recommendations for empiric antibiotics for patients requiring inpatient treatment.
Time to clinical stability. A patient’s clinical response to empiric antibiotic therapy contributes heavily to the decision regarding treatment course and duration. The IDSA/ATS guidelines recommend patients be afebrile for 48 to 72 hours and have no more than one CAP-associated sign of clinical instability before discontinuation of therapy. Although studies have used different definitions of clinical stability, the consensus guidelines refer to six parameters, which are summarized in Table 2 (right).
With appropriate antibiotic therapy, most patients hospitalized with CAP achieve clinical stability in approximately three days.6,7 Providers should expect to see some improvement in vital signs within 48 to 72 hours of admission. Should a patient fail to demonstrate objective improvement during that time, providers should look for unusual pathogens, resistant organisms, nosocomial superinfections, or noninfectious conditions.5 Certain patients, such as those with multilobar pneumonia, associated pleural effusion, or higher pneumonia-severity index scores, also take longer to reach clinical stability.8
