title: Quantitation of Chlamydia trachomatis by culture, direct immunofluorescence and competitive polymerase chain reaction.
abstract: OBJECTIVE
  Methods to quantitate Chlamydia trachomatis have never been compared although it would be relevant to periodically evaluate the sensitivity of a detection system. We compared the sensitivity and reproducibility of culture, direct immunofluorescence and the polymerase chain reaction (PCR) to quantitate C trachomatis.
  
  
  METHODS
  A competitive semiquantitative PCR procedure was developed. The number of inclusions in culture, particles by direct immunofluorescence and DNA copies by PCR were measured for 12 patient specimens. Variation was determined by measuring a sample 10 times for each method.
  
  
  RESULTS
  Patient C trachomatis major outer membrane protein gene DNA was measured semiquantitatively by amplifying together with reference DNA. DNA molecules, particles and infectious units were quantitated in clinical samples with, on average, 595 DNA molecules and 87 immunofluorescent particles observed per inclusion-forming-unit. Similar coefficients of variation (47-52%) were observed for the 3 procedures.
  
  
  CONCLUSIONS
  Competitive PCR and counting immunofluorescent particles provide reproducible and sensitive methods of quantitating C trachomatis.
authors.affiliation: Département de microbiologie, Centre hospitalier universitaire de Sherbrooke, Quebec, Canada.
authors.forename: E H
authors.initials: EH
authors.lastname: Frost
authors.forename: S
authors.initials: S
authors.lastname: Deslandes
authors.forename: D
authors.initials: D
authors.lastname: Bourgaux-Ramoisy
authors.forename: P
authors.initials: P
authors.lastname: Bourgaux
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000302:isolation & purification; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D004269:DNA, Bacterial / Q000302:isolation & purification*; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D016133:Polymerase Chain Reaction; D018272:Porins; D012680:Sensitivity and Specificity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D018272:Porins; C071677:omp1 protein, Chlamydia trachomatis