title: Microbiological cure times in acanthamoeba keratitis.
abstract: OBJECTIVE
  The purpose of this study was to estimate the duration of treatment necessary for sequential acanthamoeba laboratory tests from corneal scrapings to become negative, and to assess predictors that affect this duration period.
  
  
  METHODS
  We included all patients with at least one positive acanthamoeba culture or Giemsa stain at the F.I. Proctor Foundation Microbiology Laboratory from 1996 to 2009. A parametric survival analysis was performed among patients with repeat cultures to assess significant predictors for extended clearance time. Simulations were performed to estimate clearance time in the entire patient population, assuming imperfect sensitivity.
  
  
  RESULTS
  Thirty-seven patients with laboratory evidence of acanthamoeba had testing at 69 time points. The median clearance time among eyes with repeat cultures was 42.5 days (interquartile range (IQR) 22.0-82.0 days; unadjusted parametric model). Initial visual acuity was the only predictor significantly associated with clearance time in univariate analyses (P<0.0001). Using initial visual acuity as a predictor for clearance time among the entire patient population, the estimated clearance time decreased to 38.7 days (95% confidence interval (CI) 27.9-53.5 days). When the imperfect sensitivity of the culture technique was also taken into account, the estimated clearance time was 44.1 days (95% CI 31.9-61.0 days).
  
  
  CONCLUSIONS
  The duration of infection with acanthamoeba keratitis undergoing treatment has not been well characterized. In this report we estimate a median clearance time of approximately 6 weeks, with an IQR of 22-82 days.
authors.affiliation: Francis I. Proctor Foundation, University of California San Francisco, San Francisco, CA, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Oldenburg
authors.forename: J D
authors.initials: JD
authors.lastname: Keenan
authors.forename: V
authors.initials: V
authors.lastname: Cevallos
authors.forename: M F
authors.initials: MF
authors.lastname: Chan
authors.forename: N R
authors.initials: NR
authors.lastname: Acharya
authors.forename: B D
authors.initials: BD
authors.lastname: Gaynor
authors.forename: S D
authors.initials: SD
authors.lastname: McLeod
authors.forename: E J
authors.initials: EJ
authors.lastname: Esterberg
authors.forename: T C
authors.initials: TC
authors.lastname: Porco
authors.forename: T M
authors.initials: TM
authors.lastname: Lietman
mesh_terms: D000048:Acanthamoeba / Q000302:isolation & purification*; D015823:Acanthamoeba Keratitis / Q000188:drug therapy / Q000382:microbiology* / Q000503:physiopathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000977:Antiparasitic Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D000977:Antiparasitic Agents