Correspondence

Tick-Borne Diseases

N Engl J Med 1994; 330:292January 27, 1994

Article

To the Editor:

In their excellent review of tick-borne diseases (Sept. 23 issue),1 Spach et al. recommended tetracyclines for most adults with Rocky Mountain spotted fever and chloramphenicol for those with “prominent central nervous system manifestations of disease.” The majority of patients with Rocky Mountain spotted fever have central nervous system symptoms; Spach et al. mention that 90 percent of patients have a severe headache. I can remember few patients with the disease whose neurologic symptoms would not be considered prominent.

Although chloramphenicol penetrates the blood-brain barrier better than tetracyclines, I know of no evidence that higher antibiotic concentrations in the central nervous system are beneficial. Rickettsiae infect the endothelium and vessel wall, not the cerebral tissue. Chloramphenicol is no better than doxycycline in vitro2,3 and may be less effective in vivo for Rocky Mountain spotted fever and other rickettsioses4,5. Given the potential for chloramphenicol-induced fatal aplastic anemia, I see no reason to prescribe chloramphenicol for a situation in which it has no confirmed advantage. Of the many dozen patients with Rocky Mountain spotted fever whom I have treated with doxycycline, none have died of uncontrolled central nervous system infection.

Stanley N. Schwartz, M.D.
Inter I.D., Inc., Tulsa, OK 74136

5 References

1. 1

   Spach DH, Liles WC, Campbell GL, Quick RE, Anderson DE Jr, Fritsche TR. Tick-borne diseases in the United States. N Engl J Med 1993;329:936-947
   Full Text | Web of Science | Medline

2. 2

   Wisseman CL Jr, Ordonez SV. Actions of antibiotics on Rickettsia rickettsii. J Infect Dis 1986;153:626-628
   CrossRef | Web of Science | Medline

3. 3

   Raoult D, Drancourt M. Antimicrobial therapy of rickettsial diseases. Antimicrob Agents Chemother 1991;35:2457-2462
   Web of Science | Medline

4. 4

   Fishbein DB, Frontini MG, Giles R, Vernon LL. Fatal cases of Rocky Mountain spotted fever in the United States, 1981-1988. Ann N Y Acad Sci 1990;590:246-247
   CrossRef | Web of Science | Medline

5. 5

   Shaked Y, Samra Y, Maeir MK, Rubinstein E. Murine typhus and spotted fever in Israel in the eighties: retrospective analysis. Infection 1988;16:283-287
   CrossRef | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: We thank Dr. Schwartz for his comments. Although in vitro testing has shown that Rickettsia rickettsii is susceptible to both chloramphenicol and the tetracyclines,1-3 randomized clinical trials comparing the efficacy of these two antimicrobial agents in patients with Rocky Mountain spotted fever have not been performed. Our recommendation of chloramphenicol as the preferred agent for patients with prominent central nervous system involvement was based on the clinical circumstances that medical providers usually encounter. The diagnosis in most patients with Rocky Mountain spotted fever is not clear-cut initially; frequently, other causes of central nervous system infection, such as Neisseria meningitidis or Haemophilus influenzae, need to be considered in the differential diagnosis, especially in view of the young age of most patients in whom the disease develops. When the diagnosis is uncertain, initial empirical therapy with chloramphenicol provides an advantage over treatment with the tetracyclines, mainly because of its greater efficacy against N. meningitidis and H. influenzae. Once the diagnosis of Rocky Mountain spotted fever has been confirmed (or bacterial meningitis excluded), we would agree that chloramphenicol probably has minimal or no advantage over the tetracyclines. The tetracyclines should not be used in children under the age of eight years or in pregnant women.

W. Conrad Liles, M.D., Ph.D.
David H. Spach, M.D.
University of Washington, Seattle, WA 98104

3 References

1. 1

   Weber DJ, Walker DH. Rocky Mountain spotted fever. Infect Dis Clin North Am 1991;5:19-35
   Medline

2. 2

   Wisseman CL Jr, Ordonez SV. Actions of antibiotics on Rickettsia rickettsii. J Infect Dis 1986;153:626-628
   CrossRef | Web of Science | Medline

3. 3

   Raoult D, Drancourt M. Antimicrobial therapy of rickettsial diseases. Antimicrob Agents Chemother 1991;35:2457-2462
   Web of Science | Medline