What is the role of antibiotic therapy for the treatment of Legionnaires disease?

Updated: Mar 11, 2021
  • Author: Chinelo N Animalu, MD, MPH; Chief Editor: Michael Stuart Bronze, MD  more...
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In milder cases, patients can be treated in an outpatient setting with oral antibiotics that are targeted against legionella and are bacterocidal, have long half-lives and achieve high lung tissue concentrations. First line agents would include levofloxacin (a fluroquinolone) and azithromycin (a macrolide) administered through the oral route. Alternative agents would include other fluroquinolone s such as ciprofloxacin, moxifloxacin, doxycycline (a tetracycline). Other macrolides would include clarithromycin, erythromycin and roxithromycin. Newer tetracyclines such as tigecycline have been used as second line agents against L pneumoniae but appears to have limited activity against L longbeachae and therefore, should be avoided if this strain is suspected. [17]

For patients with L longbeachae infection, a fluroquinolone or a macrolide should be used. Treatment duration can range from 5-10 days in mild cases.

For patients with moderate or severe infection that require hospitalization, or those who cannot tolerate oral medications, the intravenous route of administration is preferred. When patients become clinically stable and can tolerate orally, they can then be transitioned to the oral equivalent. For severe disease, a fluoroquinolone is recommended. Adding rifampin to a regimen of fluroquinolone or macrolide, has not been shown to have any additional benefits. [18]

Continue oral antibiotics on an outpatient basis for 14-21 days, depending on the severity of the presenting illness. Patients should receive close follow-up care to ensure complete resolution of their respiratory symptoms.

Patients should complete the full course of antibiotics, whether the treatment is initiated in the outpatient setting or in the hospital. 

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