title: Multiplex PCR performed of bronchoalveolar lavage fluid increases pathogen identification rate in critically ill patients with pneumonia: a pilot study.
abstract: BACKGROUND
  In critically ill patients with pneumonia, accurate microorganism identification allows appropriate antibiotic treatment. In patients undergoing bronchoalveolar lavage (BAL), direct examination of the fluid using Gram staining provides prompt information but pathogen identification accuracy is low. Culture of BAL fluid is actually the reference, but it is not available before 24 to 48 h. In addition, pathogen identification rate observed with direct examination and culture is decreased when antibiotic therapy has been given prior to sampling. We therefore assessed, in critically ill patients with suspected pneumonia, the performance of a multiplex PCR (MPCR) to identify pathogens in BAL fluid. This study is a prospective pilot observation.
  
  
  METHODS
  We used a MPCR detecting 20 types of microorganisms. Direct examination, culture, and MPCR were performed on BAL fluid of critically ill patients with pneumonia suspicion. The final diagnosis of infective pneumonia was retained after the medical chart was reviewed by two experts. Pathogen identification rate of direct examination, culture, and MPCR in patients with confirmed pneumonia was compared.
  
  
  RESULTS
  Among the 65 patients with pneumonia suspicion, the diagnosis of pneumonia was finally retained in 53 cases. Twenty nine (55%) were community-acquired pneumonia and 24 (45%) were hospital acquired. Pathogen identification rate with MPCR (66%) was greater than with culture (40%) and direct examination (23%) (p =0.01 and p <0.001, respectively). When considering only the microorganisms included in the MPCR panel, the pathogen identification rate provided by MPCR reached 82% and was still higher than with culture (35%, p <0.001) and direct examination (21%, p <0.001). Pathogen identification rate provided by MPCR was not modified in the case of previous antibiotic treatment (66% vs. 64%, NS) and was still better than with culture (23%, p <0.001).
  
  
  CONCLUSIONS
  The results of this pilot study suggest that in critically ill patients, MPCR performed on BAL fluid could provide higher identification rate of pathogens involved in pneumonia than direct examination and culture, especially in patients having received antimicrobial treatment.
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Baudel
authors.affiliation: AP-HP, Hôpital Saint-Antoine, Service de Microbiologie, Paris 75012, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Tankovic
authors.affiliation: AP-HP, Hôpital Saint-Antoine, Service de Microbiologie, Paris 75012, France.
authors.forename: Redouane
authors.initials: R
authors.lastname: Dahoumane
authors.affiliation: Inserm, UMR 707, Paris 75012, France ; UPMC - Université Paris 06, Paris 75012, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Carrat
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Galbois
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France ; UPMC - Université Paris 06, Paris 75012, France.
authors.forename: Hafid
authors.initials: H
authors.lastname: Ait-Oufella
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France ; Inserm, UMR 707, Paris 75012, France ; UPMC - Université Paris 06, Paris 75012, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Offenstadt
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France ; Inserm, UMR 707, Paris 75012, France ; UPMC - Université Paris 06, Paris 75012, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Guidet
authors.affiliation: Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital Saint-Antoine, Service de Réanimation Médicale, Paris 75012, France ; Inserm, UMR 707, Paris 75012, France ; UPMC - Université Paris 06, Paris 75012, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Maury
keywords: Antibiotic therapy; Bronchoalveolar lavage; Community-acquired pneumonia; Hospital-acquired pneumonia; Multiplex PCR; Prior antibiotic treatment; SeptiFast®; Ventilator-acquired pneumonia