Tularemia in Emergency Medicine Medication

The goal of therapy is eradication of tularemia with antibiotics.

Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in context of the clinical setting. In treating tularemia, streptomycin is the drug of choice. Although less experience exists with other aminoglycosides, gentamicin also appears to be effective.

Although aminoglycosides are the drugs of choice, reports of patients who have responded well to fluoroquinolones (prior to tularemia being suspected) exist. In addition, in vitro susceptibility testing shows that the quinolones have great promise in treating tularemia. Thus, this class of drug may be an alternative in patients who cannot tolerate aminoglycosides. Also, many practitioners are using newer fluoroquinolones as monotherapy for community-acquired pneumonia.

Both levofloxacin and ciprofloxacin have been used clinically with success. In fact, in a large outbreak in Spain (142 cases), ciprofloxacin had the lowest treatment failure rate with the fewest side effects.^[4]

While tetracycline and doxycycline have been used, both are bacteriostatic and not cidal for the organism. This is also true of chloramphenicol, relegating these 3 antibiotics to a third choice.

Streptomycin

Aminoglycoside antibiotic recommended when therapeutic agents with less potential hazard are ineffective or contraindicated.

Gentamicin (Garamycin, Gentacidin)

Aminoglycoside used as an alternative to streptomycin. Less experience exists with this agent. Dosing regimens are numerous and adjusted based on creatinine clearance and changes in volume of distribution, as well as body space into which the agent must distribute. Follow each regimen by at least a trough level drawn on the third or fourth dose, 0.5 h before dosing; may draw a peak level 0.5 h after the 30-min infusion.

Tetracycline (Sumycin)

Third-line drug, tetracyclines being only bacteriostatic. Duration of treatment of < 2 wk is associated with greater risk of relapse. Only potential advantage is its ability to cover other coexisting tick-borne pathogens. Inhibits bacterial protein synthesis by binding with 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Chloramphenicol (Chloromycetin)

Insufficient data exist on use of chloramphenicol in tularemia. This agent is a distant third choice. Binds to 50S bacterial ribosomal subunit and interferes with or inhibits protein synthesis. Is effective against gram-negative and gram-positive bacteria.

Levofloxacin (Levaquin)

May be a useful agent to treat tularemia.

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. Has no activity against anaerobes. Continue treatment for at least 2 d (7-14 d typical) after signs and symptoms have disappeared.

Second DOC; in one study, was associated with lowest rate of treatment failure.

Doxycycline (Doryx, Bio-Tab, Vibramycin)

Broad-spectrum, synthetically derived bacteriostatic antibiotic in tetracycline class. Almost completely absorbed, concentrates in bile, and is excreted in urine and feces as a biologically active metabolite in high concentrations. Inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Third-line drug; bacteriostatic.