title: Direct fluorescent antibody assay and polymerase chain reaction for the detection of Chlamydia trachomatis in patients with vernal keratoconjunctivitis.
abstract: OBJECTIVE
  To identify Chlamydia trachomatis via polymerase chain reaction and a direct fluorescent antibody assay in patients with vernal keratoconjunctivitis while comparing the efficacies of both tests for detecting Chlamydia trachomatis in these conditions.
  
  
  METHODS
  Conjunctival scraping samples were obtained from 177 patients who were divided into two groups: a vernal keratoconjunctivitis group (group A) and a control group (group B). The polymerase chain reaction and a direct fluorescent antibody assay were performed. Sensitivity, specificity, receiver operating characteristic curves, and areas under the curve were calculated for both tests in groups A and B. Receiver operating characteristic curves were plotted using a categorical variable with only two possible outcomes (positive and negative).
  
  
  RESULTS
  Statistical analysis revealed a significant association between vernal keratoconjunctivitis and Chlamydia trachomatis infection detected by a direct fluorescent antibody assay with high sensitivity and specificity. All patients in group A with positive polymerase chain reactions also presented with positive direct fluorescent antibody assays.
  
  
  CONCLUSIONS
  The association between vernal keratoconjunctivitis and Chlamydia trachomatis infection was confirmed by positive direct fluorescent antibody assays in 49.4% of vernal keratoconjunctivitis patients and by positive polymerase chain reactions in 20% of these patients. The direct fluorescent antibody assay detected Chlamydia trachomatis in a higher number of patients than did the polymerase chain reaction. Although the diagnosis of trachoma is essentially clinical, the disease may not be detected in vernal keratoconjunctivitis patients. Due to the high frequency of chlamydial infection detected in patients with vernal keratoconjunctivitis, we suggest considering routine laboratory tests to detect Chlamydia trachomatis in patients with severe and refractory allergic disease.
authors.affiliation: Department of Ophthalmology, Corneal and External Disease Service, Santa Casa of São Paulo, Brazil.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Nishiwaki-Dantas
authors.forename: Mariza Toledo
authors.initials: MT
authors.lastname: de Abreu
authors.forename: Cynthia Mendonça
authors.initials: CM
authors.lastname: de Melo
authors.forename: Ivana Lopes
authors.initials: IL
authors.lastname: Romero
authors.forename: Rubens Belfort Matos
authors.initials: RB
authors.lastname: Neto
authors.forename: Paulo Elias Correa
authors.initials: PE
authors.lastname: Dantas
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002690:Chlamydia Infections / Q000175:diagnosis*; D002692:Chlamydia trachomatis / Q000235:genetics / Q000276:immunology; D002908:Chronic Disease; D003233:Conjunctivitis, Allergic / Q000175:diagnosis* / Q000382:microbiology; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D012372:ROC Curve; D012680:Sensitivity and Specificity; D055815:Young Adult