Accuracy of a routine real-time PCR assay for the diagnosis of Pneumocystis jirovecii pneumonia.
Pneumocystis jirovecii is a common cause of life-threatening pneumonia among immunocompromised patients. Using 400 fresh bronchoalveolar lavage samples, we compared prospectively routine direct immunofluorescence assay (DFA) and a real-time PCR assay, performed on a LightCycler system, for the detection of P. jirovecii. Among the 66 PCR positive samples, 31 were positive by DFA. No patient was found as having the pattern "PCR--ve/DFA+ve". The semi-quantification of the P. jirovecii DNA was represented by the cycle threshold (Ct). Using DFA as the gold standard, the sensitivity of the PCR was 100% for Ct > or = 28 and the specificity was 100% for Ct < 22. Between these two points, the results could be discrepant. The patients of the "22 < or = Ct < 28" group presented more frequently with a radiological interstitial syndrome than the "Ct > or = 28" group, and presented less frequently with HIV-infection and elevated lactate dehydrogenase (LDH) assay than in the "Ct < 22" group. A negative PCR allowed us to exclude the P. jirovecii pneumonia. The real-time PCR assay seems to be an accurate diagnosis method and could replace the DFA. The semi-quantitative results should be helpful to distinguish colonized, subclinically infected and P. jirovecii pneumonia patients.
Fillaux
Judith
J
Department of Parasitology and Mycology, Toulouse University Hospitals, France. fillaux@cict.fr
Malvy
Sonia
S
Alvarez
Muriel
M
Fabre
Richard
R
Cassaing
Sophie
S
Marchou
Bruno
B
Linas
Marie-Denise
MD
Berry
Antoine
A
D000368:Aged; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D008297:Male; D008875:Middle Aged; D045363:Pneumocystis carinii / Q000235:genetics / Q000302:isolation & purification*; D011020:Pneumonia, Pneumocystis / Q000175:diagnosis* / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
D017931:DNA Primers; D004269:DNA, Bacterial