Legionnaires Disease Medication
- Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD more...
Treat Legionnaires disease intravenously, and consider changing to oral antibiotic therapy with a 10- to 14-day course after patients begin to show signs of clinical improvement. A 21-day course is recommended in patients who are immunocompromised, who have severe underlying disease, or who develop severe Legionella pneumonia.
For immunosuppressed patients, fluoroquinolone therapy is recommended for several reasons. The fatality rate of Legionella pneumonia is high in this patient population.
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Levofloxacin, a fluoroquinolone, is used for pseudomonal infections and infections due to multidrug-resistant gram-negative organisms.
Azithromycin is a macrolide antibiotic used to treat mild to moderate microbial infections.
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 inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.
Moxifloxacin inhibits bacterial DNA synthesis and growth. Its activity is similar to that of ciprofloxacin and levofloxacin.
Rifampin is the drug of choice (DOC) to use with erythromycin. It inhibits DNA-dependent RNA polymerase activity in susceptible cells by interacting with bacterial RNA polymerase (without inhibiting the mammalian enzyme).
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 inhibits ribonucleic acid (RNA) ̶ dependent protein synthesis, possibly by stimulating dissociation of peptidyl transfer RNA (tRNA) from ribosomes. This inhibits bacterial growth.
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.
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|Diagnostic Predictors||Diagnostic Eliminators|
|Laboratory Predictors b
|Legionnaire disease very likely if >3 predictors present||Legionnaires disease very unlikely if <3 predictors or >3 diagnostic eliminators present|
|Abbreviations: CPK = creatinine phosphokinase test; CRP = C-reactive protein; ESR = erythrosedimentation rate.
a Pulmonary symptoms: shortness of breath, cough, and so forth with fever and a new focal/segmental infiltrate on chest radiograph.
b Otherwise unexplained. If finding is due to an existing disorder, it should not be used as a clinical predictor.