title: Comparison of the FXG™: RESP (Asp+) real-time PCR assay with direct immunofluorescence and calcofluor white staining for the detection of Pneumocystis jirovecii in respiratory specimens.
abstract: We compared the FXG™: RESP (Asp +) real-time PCR assay (Myconostica Ltd) with two microscopic staining methods (direct immunofluorescence [IFA] and calcofluor white) for the detection of Pneumocystis jirovecii in 411 respiratory specimens submitted for P. jirovecii examination. We considered the specimen to be microscopically positive if the organism could be visualized through the use of either IFA or calcofluor white. A second, published real-time PCR assay targeting the cdc2 gene of P. jirovecii was used to adjudicate those specimens that were microscopically negative but Myconostica PCR positive. The Myconostica PCR positive samples were deemed to be true positives if they were concordant with microscopically positive results or if they were positive by the second PCR assay. As a result, the Myconostica PCR assay was found to be more sensitive than the two microscopy methods in detecting P. jirovecii (10.5% true positivity rate by PCR, 8.0% by immunofluorescence, and 7.1% by calcofluor white). The Myconostica PCR assay showed 93.5% sensitivity, 95.1% specificity, 70.5% positive predictive value, and 99.1% negative predictive value. Its high negative predictive value suggests a role of the Myconostica PCR assay in ruling out Pneumocystis pneumonia.
authors.affiliation: Ontario Agency for Health Protection and Promotion, Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Seah
authors.forename: Susan E
authors.initials: SE
authors.lastname: Richardson
authors.forename: George
authors.initials: G
authors.lastname: Tsui
authors.forename: Billy
authors.initials: B
authors.lastname: Yu
authors.forename: John
authors.initials: J
authors.lastname: Thornback
authors.forename: Lisa
authors.initials: L
authors.lastname: McTaggart
authors.forename: Andrea
authors.initials: A
authors.lastname: Boggild
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Wengenack
authors.forename: Sean X
authors.initials: SX
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001557:Benzenesulfonates / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D019085:Fluorescent Antibody Technique, Direct / Q000379:methods*; D006801:Humans; D007223:Infant; D008297:Male; D008828:Microbiological Techniques / Q000379:methods*; D008853:Microscopy / Q000379:methods; D008875:Middle Aged; D009172:Mycology / Q000379:methods; D045363:Pneumocystis carinii / Q000302:isolation & purification*; D011020:Pneumonia, Pneumocystis / Q000175:diagnosis* / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods*; D055815:Young Adult
chemical_list: D001557:Benzenesulfonates; C007061:C.I. Fluorescent Brightening Agent 28