Development and Validation of a Pneumocystis jirovecii Real-time Polymerase Chain Reaction Assay for Diagnosis of Pneumocystis Pneumonia. Issue 5 (2015)

• Record Type: Journal Article
• Authors: Church, Deirdre L; Ambasta, Anshula; Wilmer, Amanda; Williscroft, Holly; Ritchie, Gordon; Pillai, Dylan R; Champagne, Sylvie; Gregson, Daniel G
• Is Part Of: Canadian journal of infectious diseases & medical microbiology =. Volume 26:Issue 5(2015)
• Page Start: 263
• Page End: 267
• Publication Date: 2015
• Subjects: Diagnosis -- Immunocompromised -- P jirovecii -- Pneumocystis pneumonia -- Real-time PCR; Communicable diseases -- Periodicals; Infection -- Periodicals; Communicable diseases; Infection; Communicable Diseases; Communicable Disease Control; Electronic journals; Periodicals; Fulltext; Internet Resources; Periodicals; 616.9
• DOI: 10.1155/2015/138787
• Languages: English
• ISSNs: 1712-9532

Abstract

Abstract : BACKGROUND: Pneumocystis jirovecii (PJ), a pathogenic fungus, causes severe interstitial Pneumocystis pneumonia (PCP) among immunocompromised patients. A laboratory-developed real-time polyermase chain reaction (PCR) assay was validated for PJ detection to improve diagnosis of PCP. METHODS: Forty stored bronchoalveolar lavage (BAL) samples (20 known PJ positive [PJ+] and 20 known PJ negative [PJ−]) were initially tested using the molecular assay. Ninety-two sequentially collected BAL samples were then analyzed using an immunofluorescence assay (IFA) and secondarily tested using the PJ real-time PCR assay. Discrepant results were resolved by retesting BAL samples using another real-time PCR assay with a different target. PJ real-time PCR assay performance was compared with the existing gold standard (ie, IFA) and a modified gold standard, in which a true positive was defined as a sample that tested positive in two of three methods in a patient suspected to have PCP. RESULTS: Ninety of 132 (68%) BAL fluid samples were collected from immunocompromised patients. Thirteen of 92 (14%) BALs collected were PJ+ when tested using IFA. A total of 40 BAL samples were PJ+ in the present study including: all IFA positive samples (n=13); all referred PJ+ BAL samples (n=20); and seven additional BAL samples that were IFA negative, but positive using the modified gold standard. Compared with IFA, the PJ real-time PCR had sensitivity, specificity, and positive and negative predictive values of 100%, 91%, 65% and 100%, respectively. Compared with the modified gold standard, PJ real-time PCR had a sensitivity, specificity, and positive and negative predictive values of 100%. CONCLUSION: PJ real-time PCR improved detection of PJ in immunocompromised patients.