Aspergillus PCR in serum for the diagnosis, follow-up and prognosis of invasive aspergillosis in neutropenic and nonneutropenic patients

Abstract

We evaluated the usefulness of a serum Aspergillus PCR assay for the diagnosis and prognosis of invasive aspergillosis in a study involving 941 patients for a total of 5146 serum samples. Fifty-one patients had proven/probable aspergillosis. We compared galactomannan (GM), PCR and mycologic analysis of pulmonary samples in both neutropenic and nonneutropenic patients. PCR performed in serum yielded 66.7% sensitivity, 98.7% specificity, 75.6% positive predictive value and 98.0% negative predictive value, while the GM index yielded 78.4% sensitivity, 87.5% specificity, 27% positive predictive value and 98.6% negative predictive value. The inclusion of PCR in the European Organization for Research and Treatment of Cancer (EORTC) and the Mycosis Study Group (MSG) mycologic criteria permitted the reclassification of nine other cases from possible to probable aspergillosis and increased the sensitivity to 71.7%. Combining the GM index with serum PCR increased the detection rate of invasive aspergillosis with 88.2% sensitivity. PCR was systematically negative in 16 patients with noninvasive forms of aspergillosis (namely aspergilloma and chronic aspergillosis). Remaining PCR positive after a period of 14 to 20 days of treatment was related to poor outcome at 30 and 90 days. Our results also indicate that, unlike the determination of the GM index, the initial fungus load as determined by PCR was highly predictive of 90-day mortality, with the rate of the latter being 15.8% for patients with <150 copies/mL vs. 73.2% for patients at or above that cutoff (p <0.0001). Therefore, PCR appears to be a powerful and interesting tool for the identification of patients with invasive aspergillosis who might benefit from more intense care.

Prospective Biomarker Screening for Diagnosis of Invasive Aspergillosis in High-Risk Pediatric Patients

“…PCR conversion was negatively associated with the use of liposomal amphotericin B, which is in line with the lower rate of PCR positivity when antifungal prophylaxis or therapy is used ( Table 1). As reported before (20), both tests were unable to detect noninvasive forms of IA.…”

The changes of expressive levels of IL-17A, STAT3, and ROR&gamma;t in different invasive pulmonary aspergillosis mice

“…We used a real-time PCR that targets a previously described 67 bp segment of a 28S ribosomal RNA coding DNA to detect Aspergillus DNA 13. It can be seen that the A. fumigatus fungal burden in both IPA mice were significantly higher than in the immunocompetent infected mice ( P <0.01).…”

Non-culture based assays for the detection of fungal pathogens

“…In the study, which examined diagnostic performance of PCR analysis of sera obtained from neutropenic and non-neutropenic patients, it was shown that this testing modality has higher Sn in neutropenic patients (82.1%) than in nonneutropenic patients (62.5%), but without statistical significance. Likewise, the same study noted that the initial level of Aspergillus DNA is highly predictive of the 90-day mortality rate (below 150 copies/mL-low probability; above 150 copies/mL-high probability), which is of great significance for identification of patients who may benefit from more intensive care [96]. Finally, based on all of the above facts, it can be concluded that PCR analysis of serum or plasma seems to be diagnostic modality with acceptable Sn and Sp.…”

“…Molecular techniques represent a novel approach to the diagnosis of invasive aspergillosis. Currently, PCR is the most widely applied molecular diagnostic test, which enables amplification and detection of extremely low concentrations (from 1 to 10 pg) of Aspergillus DNA in various clinical specimens such as BAL fluid, serum, plasma, whole blood and biopsy material [94,96]. Also, PCR assays can quickly identify species within the genus Aspergillus from cultures and non-cultured samples which is of great significance for epidemiologic studies and clinical practice given the fact that newly described species such as Aspergillus lentulus and Aspergillus calidoustus have been shown to have elevated minimum inhibitory concentrations (MICs) to several antifungal drugs, including azoles [95].…”

“…Studies have shown that performance of molecular tests varies depending on the specimen type and patient population [95,96]. PCR analysis of blood fractions is the most desired testing modality given that it requires minimally invasive sampling procedure [95].…”