Legionnaires Disease Medication

Updated: Mar 11, 2021
  • Author: Chinelo N Animalu, MD, MPH, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Medication Summary

Mild Legionnaires disease can be treated with a single oral antibiotic regimen that have activity against legionella pneumophila including fluroquinolones such as levofloxacin, and moxifloxacin, macrolides like azithromycin, clarithromycin. Other Tetracyclines like doxycycline can also be used as an alternative therapy.

In suspected cases of legionella longbeachae infection, either a fluroquinolone or a macrolide antibiotic should be used. Tetracyclines are not very effective against this strain of legionella and should be avoided.

In patients with severe disease that require hospitalization, intravenously antibiotics should be used initially and then consider changing to oral antibiotic therapy with a 10- to 14-day course after patients begin to show signs of clinical improvement. A 14-21-day course is recommended in patients who are immunocompromised, who have severe underlying disease, or who develop complicated Legionella pneumonia. 

For immunosuppressed patients, fluoroquinolone therapy is recommended as first line. If unable to use a fluoroquinolone, azithroycin can be used. For those on immunosuppressive medications, dose reduction maybe required. The fatality rate of Legionella pneumonia is high in this patient population.



Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Levofloxacin (Levaquin)

Levofloxacin, a fluoroquinolone, is used for pseudomonal infections and infections due to multidrug-resistant gram-negative organisms.

Azithromycin (Zithromax, Zmax)

Azithromycin is a macrolide antibiotic used to treat mild to moderate microbial infections.

Ciprofloxacin (Cipro, Cipro XR)

Ciprofloxacin is a fluoroquinolone with activity against pseudomonads, streptococci, methicillin-resistant Staphylococcus aureus (MRSA), S epidermidis, and most gram-negative organisms, but with no activity against anaerobes. It inhibits bacterial DNA synthesis and, consequently, bacterial growth.

Doxycycline (Vibramycin, Adoxa, Avidoxy, Doryx, Monodox)

Doxycycline inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Moxifloxacin (Avelox)

Moxifloxacin inhibits bacterial DNA synthesis and growth. Its activity is similar to that of ciprofloxacin and levofloxacin.

Rifampin (Rifadin)

Rifampin can be used with erythromycin although it is not routinely recommended. It inhibits DNA-dependent RNA polymerase activity in susceptible cells by interacting with bacterial RNA polymerase (without inhibiting the mammalian enzyme).

Tigecycline (Tygacil)

A glycylcycline that inhibits protein synthesis by binding to the 30S ribosomal subunit of susceptible bacteria. It has demonstrated activity against both gram-positive and gram-negative anaerobes, as well as against gram-positive aerobic strains such as methicillin-resistant staphylococci, streptococci, and enterococci.

Erythromycin base (Ery-Tab, E.E.S., PCE)

Erythromycin inhibits ribonucleic acid (RNA) ̶ dependent protein synthesis, possibly by stimulating dissociation of peptidyl transfer RNA (tRNA) from ribosomes. This inhibits bacterial growth.

Clarithromycin (Biaxin, Biaxin XL)

Clarithromycin is a macrolide antibiotic that inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.