Tularemia Medication

Updated: Feb 29, 2016
  • Author: Kerry O Cleveland, MD; Chief Editor: Burke A Cunha, MD  more...
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Medication

Medication Summary

Medical therapy in tularemia is directed at antibiotic eradication of the bacterium F tularensis. Streptomycin is the drug of choice (DOC) for this treatment; although less experience exists with other aminoglycosides, gentamicin also appears to be effective. In addition, although tetracyclines are acceptable alternatives, increasing research supports the use of fluoroquinolones in the treatment of tularemia. [5]

In vitro susceptibility testing has shown that the quinolones have great promise in treating tularemia, and reports exist of patients who responded well to fluoroquinolones prior to tularemia being suspected. Thus, these drugs may be an alternative for treating patients who cannot tolerate aminoglycosides. Also, many practitioners are using newer fluoroquinolones as monotherapy for community-acquired pneumonia.

Levofloxacin and ciprofloxacin have been used clinically with success. In fact, in a large tularemia outbreak in Spain (142 cases), ciprofloxacin had a lower treatment failure rate and fewer side effects than did streptomycin and doxycycline. [61]

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Antibiotics

Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens for the clinical presentation. Streptomycin is considered the antimicrobial of choice in tularemia therapy.

While chloramphenicol and tetracycline are also clinically useful against tularemia, relapse rates of up to 50% have been reported with these agents.

Research increasingly supports the use of fluoroquinolones to treat the disease, but clinical experience and in vitro data regarding their efficacy are limited. [5]

Streptomycin

Streptomycin is an aminoglycoside antibiotic traditionally considered to be the DOC for tularemia. It has been administered safely intravenously but is usually administered intramuscularly.

Gentamicin

This aminoglycoside may be used as an alternative to streptomycin, although there has been less clinical experience with gentamicin than with streptomycin in the treatment of tularemia. The drug may be administered intravenously or intramuscularly. Many dosing schedules are based on creatinine clearance (CrCl), volume of distribution, site of infection, and type of infection. Monitor serum levels after steady state is reached (usually after 3-4 doses). Trough levels are usually obtained 0.5 hour before the dose; peak levels are usually obtained 1 hour after the dose is infused.

Doxycycline (Adoxa, Alodox, Doxy 100, Doryx, Vibramycin)

Doxycycline is a broad-spectrum, synthetically derived, bacteriostatic antibiotic in the tetracycline class. It is almost completely absorbed, concentrates in bile, and is excreted in urine and feces as a biologically active metabolite in high concentrations. The drug inhibits protein synthesis (and thus bacterial growth) by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Doxycycline may block dissociation of peptidyl transfer ribonucleic acid (t-RNA) from ribosomes, causing RNA-dependent protein synthesis to arrest. It may eradicate not only F tularensis, but also other tick-related co-pathogens. Doxycycline should be used for a full 14 days to prevent risk of relapse.

Chloramphenicol (Chloromycetin)

Chloramphenicol binds to 50S bacterial ribosomal subunits and inhibits bacterial growth by inhibiting protein synthesis. It is effective against gram-negative and gram-positive bacteria.

There is insufficient data on chloramphenicol's use in the treatment of tularemia. It is a distant third or possibly fourth choice for tularemia therapy given growing evidence supporting the use of fluoroquinolones.

Tetracycline

Tetracycline is a third-line drug for the treatment of tularemia, since the tetracyclines are only bacteriostatic. Treatment that lasts less than 2 weeks is associated with a greater risk of relapse. The only potential advantage to the use of tetracycline is its ability to cover other, coexisting tick-borne pathogens.

The drug inhibits bacterial protein synthesis by binding with 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Levofloxacin (Levaquin)

This agent may be useful to treat tularemia.

Ciprofloxacin (Cipro)

Ciprofloxacin is a 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 but no activity against anaerobes. Continue treatment for at least 2 days (7-14 days are typical) after signs and symptoms disappear.

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