title: Acanthamoeba, fungal, and bacterial keratitis: a comparison of risk factors and clinical features.
abstract: OBJECTIVE
  To determine risk factors and clinical signs that may differentiate between bacterial, fungal, and acanthamoeba keratitis among patients presenting with presumed infectious keratitis.
  
  
  METHODS
  Hospital-based cross-sectional study.
  
  
  METHODS
  We examined the medical records of 115 patients with laboratory-proven bacterial keratitis, 115 patients with laboratory-proven fungal keratitis, and 115 patients with laboratory-proven acanthamoeba keratitis seen at Aravind Eye Hospital, Madurai, India, from 2006-2011. Risk factors and clinical features of the 3 organisms were compared using multinomial logistic regression.
  
  
  RESULTS
  Of 95 patients with bacterial keratitis, 103 patients with fungal keratitis, and 93 patients with acanthamoeba keratitis who had medical records available for review, 287 (99%) did not wear contact lenses. Differentiating features were more common for acanthamoeba keratitis than for bacterial or fungal keratitis. Compared to patients with bacterial or fungal keratitis, patients with acanthamoeba keratitis were more likely to be younger and to have a longer duration of symptoms, and to have a ring infiltrate or disease confined to the epithelium.
  
  
  CONCLUSIONS
  Risk factors and clinical examination findings can be useful for differentiating acanthamoeba keratitis from bacterial and fungal keratitis.
authors.affiliation: Department of Cornea and External Diseases, Aravind Eye Care System, Madurai, India.
authors.forename: Jeena
authors.initials: J
authors.lastname: Mascarenhas
authors.affiliation: Department of Ocular Microbiology, Aravind Eye Care System, Madurai, India.
authors.forename: Prajna
authors.initials: P
authors.lastname: Lalitha
authors.affiliation: Department of Cornea and External Diseases, Aravind Eye Care System, Madurai, India.
authors.forename: N Venkatesh
authors.initials: NV
authors.lastname: Prajna
authors.affiliation: Department of Cornea and External Diseases, Aravind Eye Care System, Madurai, India.
authors.forename: Muthiah
authors.initials: M
authors.lastname: Srinivasan
authors.affiliation: Department of Cornea and External Diseases, Aravind Eye Care System, Madurai, India.
authors.forename: Manoranjan
authors.initials: M
authors.lastname: Das
authors.affiliation: Department of Cornea and External Diseases, Aravind Eye Care System, Madurai, India.
authors.forename: Sean S
authors.initials: SS
authors.lastname: D'Silva
authors.affiliation: Francis I. Proctor Foundation, University of California, San Francisco, California.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Oldenburg
authors.affiliation: Francis I. Proctor Foundation, University of California, San Francisco, California.
authors.forename: Durga S
authors.initials: DS
authors.lastname: Borkar
authors.affiliation: Francis I. Proctor Foundation, University of California, San Francisco, California.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Esterberg
authors.affiliation: Francis I. Proctor Foundation, University of California, San Francisco, California; Department of Ophthalmology, University of California, San Francisco, California; Department of Epidemiology & Biostatistics, University of California, San Francisco, California.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Lietman
authors.affiliation: Francis I. Proctor Foundation, University of California, San Francisco, California; Department of Ophthalmology, University of California, San Francisco, California. Electronic address: jeremy.keenan@ucsf.edu.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Keenan
mesh_terms: D015823:Acanthamoeba Keratitis / Q000175:diagnosis* / Q000209:etiology; D000328:Adult; D001419:Bacteria / Q000302:isolation & purification; D003320:Corneal Ulcer / Q000175:diagnosis* / Q000382:microbiology / Q000469:parasitology; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D015818:Eye Infections, Bacterial / Q000175:diagnosis* / Q000209:etiology; D015821:Eye Infections, Fungal / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D005658:Fungi / Q000302:isolation & purification; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors