title: Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms.
abstract: OBJECTIVE
  To investigate the risk factors and control mechanisms used to control the outbreak of diffuse lamellar keratitis (DLK) associated with laser in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs.
  
  
  METHODS
  Clinic-based cohort and laboratory study.
  
  
  METHODS
  All patients undergoing LASIK at our clinic from October 7, 1998 through August 31, 1999. The case definition was a diffuse infiltrate in the interface developing within the first week after surgery.
  
  
  METHODS
  Biofilm control in the sterilizer, changes in sterilizer, distilled water, instruments, and irrigating fluids.
  
  
  METHODS
  The incidence of DLK after LASIK surgery.
  
  
  RESULTS
  There were 983 evaluable patients, with three whose DLK status was not recorded. There were 52 cases of DLK. Burkholderia pickettii was isolated from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, saline solutions used, time of day the surgery was performed, and microkeratome use. Sterilizers 1 and 2, before biofilm control, were compared with sterilizer 3, after control. The relative risk was 9.4 (confidence limits [CL], 7.5-11.8) for sterilizer 1 versus 3 and 18. 7 (CL, 11-32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic in nature and associated with epithelial defects.
  
  
  CONCLUSIONS
  Clusters of DLK may be related to endotoxins released from gram-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer reservoir. Epidemiologic investigation showed that biofilm control in the sterilizer reservoirs was associated with a significant reduction in the development of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectiveness of sterilizer biofilm control.
authors.affiliation: Department of Ophthalmology, University of British Columbia, Vancouver, British Columbia, Canada. Simon_Holland@telus.net
authors.forename: S P
authors.initials: SP
authors.lastname: Holland
authors.forename: R G
authors.initials: RG
authors.lastname: Mathias
authors.forename: D W
authors.initials: DW
authors.lastname: Morck
authors.forename: J
authors.initials: J
authors.lastname: Chiu
authors.forename: S G
authors.initials: SG
authors.lastname: Slade
mesh_terms: D000293:Adolescent; D000328:Adult; D018441:Biofilms; D001955:British Columbia / Q000453:epidemiology; D019117:Burkholderia / Q000302:isolation & purification; D002648:Child; D015331:Cohort Studies; D003315:Cornea / Q000601:surgery; D004196:Disease Outbreaks; D004731:Endotoxins / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D007634:Keratitis / Q000139:chemically induced / Q000453:epidemiology* / Q000517:prevention & control; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013242:Sterilization / Q000295:instrumentation*; D014871:Water Microbiology
chemical_list: D004731:Endotoxins