Legionella Infection Medication

Updated: Nov 13, 2018
  • Author: Mobeen H Rathore, MD, CPE, FAAP, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Medication Summary

Early initiation of antibiotic therapy with antilegionellosis agents substantially reduces the mortality rate.



Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the clinical setting. Whenever feasible, select antibiotics on the basis of blood-culture sensitivity.

Azithromycin (Zithromax)

Binds to 50S ribosomal subunit of susceptible microorganisms and blocks dissociation of peptidyl tRNA from ribosomes, arresting RNA-dependent protein synthesis. Nucleic acid synthesis not affected. Concentrates in phagocytes and fibroblasts, as demonstrated with in vitro incubation techniques. In vivo data suggest that concentration in phagocytes may contribute to drug distribution to inflamed tissues. Used to treat mild-to-moderate microbial infections. Plasma concentrations are low but tissue concentrations are high, giving it value in treating intracellular organisms. Has long tissue half-life, and single dose recommended.

Rifampin (Rifadin)

Use with azithromycin. Inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically interacts with bacterial RNA polymerase but does not inhibit mammalian enzyme.

Doxycycline (Doryx, Vibramycin)

Broad-spectrum, synthetically derived bacteriostatic antibiotic in tetracycline class. Almost completely absorbed, concentrated in bile, and excreted in urine and feces as biologically active metabolite in high concentrations.

Inhibits protein synthesis and therefore bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl t-RNA from ribosomes, arresting RNA-dependent protein synthesis.

Ciprofloxacin (Cipro)

Fluoroquinolone that inhibits bacterial DNA synthesis and consequently growth, by inhibiting DNA gyrase and topoisomerases, which are required for replication, transcription, and translation of genetic material. Quinolones have broad activity against gram-positive and gram-negative aerobic organisms. No activity against anaerobes. Continue for at least 2 d (7-14 d typical) after signs and symptoms disappear.

Levofloxacin (Levaquin)

Fluoroquinolone antibiotic for pseudomonal infections and infections caused by multidrug-resistant gram-negative organisms.

Trimethoprim and sulfamethoxazole, TMP-SMZ (Bactrim, Septra)

Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid. Antibacterial activity against common urinary tract pathogens, except Pseudomonas aeruginosa.