title: Evaluation of quantitative PCR for early diagnosis of Pseudomonas aeruginosa infection in cystic fibrosis: a prospective cohort study.
abstract: OBJECTIVE
  Early detection of Pseudomonas aeruginosa lung positivity is a key element in cystic fibrosis (CF) management. PCR has increased the accuracy of detection of many microorganisms. Clinical relevance of P. aeruginosa quantitative PCR (qPCR) in this context is unclear. Our aim was to determine P. aeruginosa qPCR sensitivity and specificity, and to assess the possible time saved by qPCR in comparison with standard practice (culture).
  
  
  METHODS
  A multicentre cohort study was conducted over a 3-year period in 96 patients with CF without chronic P. aeruginosa colonization. Sputum samples were collected at each visit. Conventional culture and two-step qPCR (oprL qPCR and gyrB/ecfX qPCR) were performed for 707 samples. The positivity criteria were based on the qPCR results, defined in a previous study as follow: oprL qPCR positivity alone if bacterial density was <730 CFU/mL or oprL qPCR combined with gyrB/ecfX qPCR if bacterial density was ≥730 CFU/mL.
  
  
  RESULTS
  During follow up, 36 of the 96 patients with CF were diagnosed on culture as colonized with P. aeruginosa. This two-step qPCR displayed a sensitivity of 94.3% (95% CI 79.7%-98.6%), and a specificity of 86.3% (95% CI 83.4%-88.7%). It enabled P. aeruginosa acquisition to be diagnosed earlier in 20 patients, providing a median detection time gain of 8 months (interquartile range 3.7-17.6) for them.
  
  
  CONCLUSIONS
  Implementing oprL and gyrB/ecfX qPCR in the management of patients with CF allowed earlier detection of first P. aeruginosa lung positivity than culture alone.
authors.affiliation: EA 3882-Laboratoire de Biodiversité et d'Ecologie Microbienne, Faculté de Médecine, Université de Brest, Brest, France; Département de Bactériologie-Virologie, Hygiène Hospitalière et Parasitologie-Mycologie, CHRU Brest, Brest, France. Electronic address: genevieve.hery-arnaud@chu-brest.fr.
authors.forename: G
authors.initials: G
authors.lastname: Héry-Arnaud
authors.affiliation: INSERM CIC 1412, CHRU Brest, Brest, France.
authors.forename: E
authors.initials: E
authors.lastname: Nowak
authors.affiliation: Laboratoire de Bactériologie-Virologie et Hygiène Hospitalière, CHU Nantes, Nantes, France.
authors.forename: J
authors.initials: J
authors.lastname: Caillon
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose Enfants, CHU Nantes, Nantes, France.
authors.forename: V
authors.initials: V
authors.lastname: David
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: A
authors.initials: A
authors.lastname: Dirou
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: K
authors.initials: K
authors.lastname: Revert
authors.affiliation: Département de Pédiatrie et de Génétique Médicale, CHRU Brest, Brest, France.
authors.forename: M-R
authors.initials: MR
authors.lastname: Munck
authors.affiliation: Département de Médecine Interne et de Pneumologie, CHRU Brest, Brest, France.
authors.forename: I
authors.initials: I
authors.lastname: Frachon
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose Adultes, CHU Nantes, Nantes, France.
authors.forename: A
authors.initials: A
authors.lastname: Haloun
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose Adultes, CHU Nantes, Nantes, France.
authors.forename: D
authors.initials: D
authors.lastname: Horeau-Langlard
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: J
authors.initials: J
authors.lastname: Le Bihan
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose Adultes, CHU Nantes, Nantes, France.
authors.forename: I
authors.initials: I
authors.lastname: Danner-Boucher
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: S
authors.initials: S
authors.lastname: Ramel
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: M-P
authors.initials: MP
authors.lastname: Pelletier
authors.affiliation: INSERM CIC 1412, CHRU Brest, Brest, France.
authors.forename: S
authors.initials: S
authors.lastname: Rosec
authors.affiliation: EA 3882-Laboratoire de Biodiversité et d'Ecologie Microbienne, Faculté de Médecine, Université de Brest, Brest, France.
authors.forename: S
authors.initials: S
authors.lastname: Gouriou
authors.affiliation: INSERM CIC 1412, CHRU Brest, Brest, France.
authors.forename: E
authors.initials: E
authors.lastname: Poulhazan
authors.affiliation: EA 3882-Laboratoire de Biodiversité et d'Ecologie Microbienne, Faculté de Médecine, Université de Brest, Brest, France; Département de Bactériologie-Virologie, Hygiène Hospitalière et Parasitologie-Mycologie, CHRU Brest, Brest, France.
authors.forename: C
authors.initials: C
authors.lastname: Payan
authors.affiliation: UMR1078, Institut National de la Santé et de la Recherche Médicale, Brest, France; Laboratoire de Génétique Moléculaire, CHRU Brest, France; Faculté de Médecine et des Sciences de la Santé, Université de Brest, France; Etablissement Français du Sang-Bretagne, Brest, France.
authors.forename: C
authors.initials: C
authors.lastname: Férec
authors.affiliation: Centre de Ressources et de Compétences Mucoviscidose, Centre de Perharidy, Roscoff, France.
authors.forename: G
authors.initials: G
authors.lastname: Rault
authors.affiliation: INSERM CIC 1412, CHRU Brest, Brest, France.
authors.forename: G
authors.initials: G
authors.lastname: Le Gal
authors.affiliation: EA 3882-Laboratoire de Biodiversité et d'Ecologie Microbienne, Faculté de Médecine, Université de Brest, Brest, France; Département de Médecine Interne et de Pneumologie, CHRU Brest, Brest, France. Electronic address: rozenn.leberre@chu-brest.fr.
authors.forename: R
authors.initials: R
authors.lastname: Le Berre
mesh_terms: D000293:Adolescent; D001431:Bacteriological Techniques / Q000379:methods; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000175:diagnosis*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D013997:Time Factors
keywords: Cystic fibrosis; Early diagnosis; Pseudomonas aeruginosa; Quantitative PCR; Sensitivity; Specificity