title: Failure of treatment with cephalexin for Lyme disease.
abstract: BACKGROUND
  Lyme disease typically presents with a skin lesion called erythema migrans (EM), which though often distinctive in appearance may be confused with cellulitis. The first-generation cephalosporin, cephalexin monohydrate, is effective for treating bacterial cellulitis but has not been recommended or studied for treating Lyme disease because of poor in vitro activity.
  
  
  OBJECTIVE
  To describe the outcome of patients with EM who were treated with cephalexin.
  
  
  METHODS
  Patients presenting with EM to the Lyme Disease Diagnostic Center in Westchester, NY (May 1992-September 1997). A 2-mm punch biopsy specimen of the leading edge of the EM lesion and/or blood was cultured for Borrelia burgdorferi.
  
  
  RESULTS
  Eleven (2.8%) of 393 study patients had been initially treated with cephalexin prior to our evaluation; 9 (82%) were originally diagnosed with cellulitis. Cephalexin was administered for 8.6 days (range, 2-21 days) prior to presentation. All 11 patients had clinical evidence of disease progression, including 8 whose rash enlarged, 2 who developed seventh-nerve palsy (1 with new EM lesions), and 1 who developed new EM lesions. Borrelia burgdorferi grew in cultures from 5 patients despite a mean of 9.8 days of treatment with cephalexin (range, 5-21 days).
  
  
  CONCLUSIONS
  Cephalexin should not be used to treat early Lyme disease and should be prescribed with caution during the summer months for patients believed to have cellulitis in locations where Lyme disease is endemic.
authors.affiliation: Division of Infectious Diseases, Westchester Medical Center, New York Medical College, Valhalla, USA. John-Nowakowski@nymc.edu
authors.forename: J
authors.initials: J
authors.lastname: Nowakowski
authors.forename: D
authors.initials: D
authors.lastname: McKenna
authors.forename: R B
authors.initials: RB
authors.lastname: Nadelman
authors.forename: D
authors.initials: D
authors.lastname: Cooper
authors.forename: S
authors.initials: S
authors.lastname: Bittker
authors.forename: D
authors.initials: D
authors.lastname: Holmgren
authors.forename: C
authors.initials: C
authors.lastname: Pavia
authors.forename: R C
authors.initials: RC
authors.lastname: Johnson
authors.forename: G P
authors.initials: GP
authors.lastname: Wormser
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D015748:Borrelia burgdorferi Group / Q000187:drug effects*; D002506:Cephalexin / Q000627:therapeutic use*; D002511:Cephalosporins / Q000627:therapeutic use*; D004318:Doxycycline / Q000031:analogs & derivatives / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008193:Lyme Disease / Q000188:drug therapy* / Q000382:microbiology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004318:Doxycycline; D002506:Cephalexin