Azithromycin also offers potential for short courses of therapy, as pulmonary concentrations of azithromycin remain elevated for as many as five days following a single oral dose.14 Several small studies have demonstrated the safety, efficacy, and cost-effectiveness of three to five days of azithromycin, as summarized in a meta-analysis by Contopoulos-Ioannidis and colleagues.15 Most of these trials, however, were limited to outpatients or inpatients with mild disease or confirmed atypical pneumonia. One randomized trial of 40 inpatients with mild to moderately severe CAP found comparable clinical outcomes with a three-day course of oral azithromycin 500 mg daily versus clarithromycin for at least eight days.16 Larger studies in more severely ill patients must be completed before routinely recommending this approach in hospitalized patients. Furthermore, due to the rising prevalence of macrolide resistance, empiric therapy with a macrolide alone can only be used for the treatment of carefully selected hospitalized patients with nonsevere diseases and without risk factors for drug-resistant Streptococcus pneumoniae.5
Telithromycin is a ketolide antibiotic, which has been studied in mild to moderate CAP, including multidrug-resistant strains of S. pneumoniae, in courses of five to seven days.17 However, severe adverse reactions, including hepatotoxicity, have been reported. At the time of the 2007 guidelines, the IDSA/ATS committee waited for additional safety data before making any recommendations on its use.
One additional study of note was a trial of amoxicillin in adult inpatients with mild to moderately severe CAP.18 One hundred twenty-one patients who clinically improved (based on a composite score of pulmonary symptoms and general improvement) following three days of IV amoxicillin were randomized to oral amoxicillin for an additional five days or given a placebo. At days 10 and 28, there was no difference in clinical success between the two groups. The authors concluded that a total of three days of treatment was not inferior to eight days in patients who substantially improved after the first 72 hours of empiric treatment. This trial was conducted in the Netherlands, where amoxicillin is the preferred empiric antibiotic for CAP and patterns of antimicrobial resistance differ greatly from those found in the U.S.
Other considerations. While some evidence supports shorter courses of antibiotics, many of the existing studies are limited by their inclusion of outpatients, adults with mild to moderate CAP, or small sample size. Hence, clinical judgment continues to play an important role in determining the appropriate duration of therapy. Factors such as pre-existing co-morbidities, severity of illness, and occurrence of complications should be considered. Data is limited on the appropriate duration of antibiotics in CAP patients requiring intensive care. It also is important to note the IDSA/ATS recommendations and most of the studies reviewed exclude patients with human immunodeficiency virus (HIV), and it is unknown whether these shorter courses of antibiotics are appropriate in the HIV population.
Lastly, the IDSA/ATS guidelines note longer durations of treatment may be required if the initial therapy was not active against the identified pathogen, or in cases complicated by extrapulmonary infections, such as endocarditis or meningitis.
Back to the Case
Our patient with moderately severe CAP was hospitalized based on his age and hypoxia. He was immediately treated with supplemental oxygen by nasal cannula, IV fluids, and a dose of IV levofloxacin 750 mg. Within 48 hours he met criteria for clinical stability, including defervescence, a decline in his respiratory rate to 19 breaths per minute, and improvement in oxygen saturation to 95% on room air. At this point, he was changed from IV to oral antibiotics. He continued on levofloxacin 750 mg daily and later that day was discharged home in good condition to complete a five-day course.