Efficacy of Antibiotics for Community-Acquired Pneumonia Evaluated

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Older age and existence of co-morbidities contributed to higher failure rates.
Older age and existence of co-morbidities contributed to higher failure rates.

Researchers are calling for an update to community-acquired pneumonia (CAP) treatment guidelines after a new study found that over one-fifth of those prescribed an antibiotic for CAP, experienced treatment failure.

While current CAP guidelines from the American Thoracic Society and the Infectious Disease Society of America (2007) provide some direction for outpatient antibiotic selection, a group of researchers lead by Dr. James A. McKinnell of LA BioMed, sought to identify and interpret data from ‘real-world' settings. They conducted a retrospective cohort analysis assessing outpatient CAP data from MarketScan between the years 2011 to 2015. The full findings of the study were presented at the 2017 American Thoracic Society (ATS) Annual Meeting held May 19-24, in Washington, DC.1

The records of 251,947 patients with CAP treated with either a beta-lactam, macrolide, tetracycline, or fluoroquinolone were examined; the majority of patients were prescribed azithromycin (40.3%) or levofloxacin (37.7%). The researchers found that the total treatment failure rate was 22.1%, defined as either the need to refill antibiotic prescriptions, antibiotic switch, ER visit or hospitalization within 30 days of receiving initial antibiotic prescription. The breakdown of failure rate was: antibiotic refill (n=11,493/55,741, 20.6%), antibiotic switch (n=39,397/55,741, 70.7%), ER visit (n=1,835/55,741, 3.3%) and hospitalization (n=3,015/55,741, 5.4%).

When divided by antibiotic class, the failure rates were 25.7% for beta-lactams, 22.9% for macrolides, 22.5% for tetracyclines, and 20.8% for fluoroquinolones after adjusting for baseline patient characteristics. Older age and existence of co-morbidities contributed to higher failure rates. 

“Our findings suggest that the community-acquired pneumonia treatment guidelines should be updated with more robust data on risk factors for clinical failure,” said Dr. McKinnell.2 "Patients over the age of 65 were nearly twice as likely to be hospitalized compared to younger patients when our analysis was risk adjusted and nearly three times more likely in unadjusted analysis."

In addition, the researchers found that patients with co-morbidities, such as chronic obstructive pulmonary disease and diabetes were not treated with combination antibiotic therapy or respiratory fluoroquinolone, as the guidelines recommend. 

"Prescribers should be aware of those CAP patients at risk for poor outcomes and consider these factors to guide a comprehensive treatment plan, including more appropriate antibiotic treatment," they concluded. 


  1. McKinnell J, Classi P, Blumberg P, Murty S, Tillotson G. Clinical predictors of antibiotic failure in adult outpatients with community-acquired pneumonia. Presented at: ATS 2017 International Conference. Washington, DC; May 19-24. Abstract 8450.
  2. Antibiotic therapy for nearly one in four adults with pneumonia does not work [press release]. New York, NY: American Thoracic Society. http://www.thoracic.org/about/newsroom/press-releases/conference/2017/mcKinnell-antibiotic-therapy-for-pneumonia.php Published May 21, 2017. Accessed May 23, 2017.
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