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Dissociation between inhibition and killing by levofloxacin in human granulocytic anaplasmosis

Gary P Wormser1, Alina Filozov, Sam R Telford

  • 1Division of Infectious Diseases, Depatment of Medicine, New York Medical College, Westcheser Medical Center, Valhalla, New York, USA. Gary_Wormser@nymc.edu

Vector Borne and Zoonotic Diseases (Larchmont, N.Y.)
|December 26, 2006
PubMed

Insights

Levofloxacin showed activity against Human Granulocytic Anaplasmosis (HGA) in vitro and in a patient. However, relapse occurred after treatment, indicating fluoroquinolones are not curative for HGA.

Area of Science:

  • * Infectious Diseases
  • * Microbiology
  • * Tick-borne Illnesses

Background:

  • * Human granulocytic anaplasmosis (HGA) is a severe, tick-borne disease caused by *Anaplasma phagocytophilum*.
  • * Doxycycline is the primary treatment, but alternative options are being explored due to limited choices.
  • * Fluoroquinolones, like levofloxacin, exhibit in vitro activity against *A. phagocytophilum*.

Observation:

  • * A hospitalized HGA patient initially improved with a 13-day levofloxacin course.
  • * The patient experienced clinical and microbiological relapse 15 days post-treatment.
  • * Levofloxacin treatment failure was replicated in a severe combined immune-deficient (SCID) mouse model.

Findings:

  • * Levofloxacin therapy resulted in a temporary improvement but not a cure for HGA.
  • * Relapse of *Anaplasma phagocytophilum* infection occurred despite initial response to levofloxacin.
  • * The SCID mouse model confirmed the ineffectiveness of levofloxacin in eradicating HGA.

Implications:

  • * Fluoroquinolones, including levofloxacin, should not be considered a definitive cure for HGA.
  • * Further research is needed to identify effective and curative treatment regimens for HGA.
  • * This study highlights the potential for relapse and the limitations of current alternative therapies for HGA.

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