TABLE 5.
Clinical studies evaluating Candida PCRa
| Study (reference no.) | Study design | Patient population | Type of PCR | Type of specimen tested | Primer target | Method utilized to determine accuracy | Sensitivity (%) | Specificity (%) | Comments |
|---|---|---|---|---|---|---|---|---|---|
| Ahmad et al., 2002 (185) | Retrospective | 28 culture-proven or suspected Candida-positive patients, 10 superficially colonized patients, 12 healthy controls | Seminested PCR | Serum | ITS2 | Comparison to blood culture results | 100 | 100 | The approach was able to identify Candida species in 9 culture-negative patients with suspected IC. All Candida-colonized patients had negative PCR results. |
| White et al., 2003 (186) | Prospective | 113 patients at risk for IC | Real-time PCR and nested PCR | Whole blood | 18S rDNA | NA | NA | NA | Only 3 of the 113 patients had blood culture-positive results, 2 of whom also had positive PCR results. PCR was positive in another 25 patients suspected to have IC. |
| Tirodker et al., 2003 (187) | Prospective | 70 pediatric and neonatal ICU patients with sepsis | Traditional PCR with gel electrophoresis | Whole blood | 18S rDNA | Comparison to blood culture results | 100 | 77.2 | Seven of 13 culture-negative and PCR-positive patients had other evidence of IFI. |
| Maaroufi et al., 2003 (118) | Retrospective | 61 hemato-oncology patients with proven or suspected IC | Real-time PCR with hydrolysis probes | Whole blood | 5.8S and 28S rDNA | Comparison to blood culture results | 100 | 97 | |
| Maaroufi et al., 2004 (188) | Retrospective | 39 patients with clinically proven or suspected Candida infection and 15 controls | Real-time PCR with fluorescent probes | Serum | 5.8S and 28S rDNA | Comparison to blood culture results | 100 | 97 | |
| Ahmad et al., 2004 (189) | Retrospective | 26 patients (6 proven cases, 10 suspected cases, 10 healthy controls) | Seminested PCR-ELISA | Serum | 5.8S and 28S rDNA and ITS2 | Comparison to blood culture results | 100 | 80 | PCR was positive in 4 of 10 patients with suspected IC and in none of the healthy controls. |
| White et al., 2005 (190) | Retrospective | 105 patients at high risk for IFI | Real-time PCR with fluorescent probe | Whole blood and serum | 18S rDNA | Comparison to EORTC/MSG criteria | 95 for proven and probable cases | 97 | Possible IC cases were not included in the sensitivity and specificity determinations. |
| Moreira-Oliveira et al., 2005 (191) | Prospective | 225 patients with hematologic malignancies and at risk for IC | Traditional PCR followed by sequencing | Whole blood | 5.8S rDNA | Comparison to blood culture results | 72.1 | 91.2 | |
| Alam et al., 2007 (192) | Retrospective | 27 patients with culture-proven Candida infection, 39 patients with suspected candidemia, 10 colonized patients, 16 controls | Seminested PCR | Serum | ITS2 | Comparison to EORTC/MSG criteria | 92.5 | 100 | Probable IC cases were excluded from analysis (53% of them were PCR positive). |
| McMullan et al., 2008 (193) | Prospective | 157 nonneutropenic patients in the ICU | Real-time PCR with hydrolysis probes | Serum | 18S and 5.8S rDNA, ITS1, ITS2 | Comparison to EORTC/MSG criteria, modified for nonneutropenic patients | 82 | 100 | Probable IC patients were excluded from the analysis. One of the 11 patients with proven IC was diagnosed with Candida famata infection, which was not possible to detect with the primers used. |
| Dunyach et al., 2008 (194) | Prospective | 23 ICU patients with cancer and 10 healthy controls | Real-time PCR with SYBR green fluorescence | Serum | ITS1 to ITS4, L18 | Comparison to blood culture results | 92 for L18 PCR, 76.9 for ITS PCR | 66 for L18 PCR, 100 for ITS PCR | Patients with probable IC were excluded from the analysis. Among the 10 patients with probable IC, 3 were positive with L18 PCR and 5 with ITS PCR. |
| Metwally et al., 2008 (195) | Retrospective | 104 patients included in a previous prospective study, from whom whole-blood specimens were obtained | Real-time PCR with hydrolysis probes | Whole blood and serum | 18S and 5.8S rDNA, ITS1, ITS2 | Comparison to EORTC/MSG criteria, modified for nonneutropenic patients | 100 for serum, 70 for whole blood | 100 | |
| Badiee et al., 2009 (196) | Prospective | 194 patients with hematologic malignancies | PCR-ELISA | Whole blood | 18S rDNA | Comparison to EORTC/MSG criteria | 100 (2 of 2 proven IC cases) | 95 | Patients with probable IC and patients with fever of unknown origin were excluded from the analysis. PCR remained positive until death when treatment failed. |
| Khlif et al., 2009 (197) | Prospective | 110 patients at risk for IC | Real-time and nested PCR assays | Blood cultures | 18S and 5.8S rDNA, ITS1, ITS2 | Comparison to blood cultures | 81 for real-time PCR, 86 for nested PCR | 96 for real-time PCR, 54 for nested PCR | |
| Wellinghausen et al., 2009 (198) | Prospective | 284 patients at risk for IC | Real-time PCR | Whole blood | 18S rDNA | Comparison to blood cultures | 87.5 | 93 | PCR also detected Candida DNA in 8 blood culture-negative patients with Candida isolated from culture-sterile sites. |
| Badiee et al., 2010 (199) | Prospective | 35 patients with bone marrow transplant | Real-time PCR with hydrolysis probes | Whole blood | 18S rDNA | Comparison to EORTC/MSG criteria | 100 (probable IC cases were considered truly positive) | 88.9 (increased to 100 when only patients with at least two positive PCR results were considered PCR positive) | |
| Lau et al., 2010 (200) | Retrospective | 109 patients with or at risk for candidemia | Multiplex tandem PCR | Whole blood | ITS1, ITS2, elongation factor 1a, β-tubulin | Comparison to blood cultures | 75 | 97 | Results were accelerated by an average of 2.2 days compared to culture. Serum and plasma PCRs were more sensitive with the few serum samples that were tested. |
| Schell et al., 2012 (201) | Retrospective | 16 patients with culture-proven Candida infection | Real-time and microfluidic PCR | Whole blood | ITS1, ITS2 | Comparison to blood cultures | 68.7 for real-time PCR, 56.2 for microfluidic PCR | NA due to study design | |
| Trovato et al., 2012 (202) | Retrospective | 86 neonatal ICU patients with suspected bloodstream infections | PCR followed by ethidium bromide staining | Blood cultures | 18S rDNA, ITS1, 28S rDNA | Comparison to EORTC/MSG criteria | 87.5 for proven and probable IC | 98.6 for no IC | For comparison, the sensitivity and specificity of the blood culture results were 50% and 100%, respectively. |
| Nguyen et al., 2012 (4) | Retrospective | 55 patients with IC and 73 hospitalized controls | Real-time PCR with fluorescently labeled probes | Whole blood, plasma, serum | ITS1, ITS2 | IC was defined as recovery of Candida from blood or a sterile site; controls were defined as those having no clinical or microbiological evidence of IC | 80 | 70 | “Positive PCR” was defined as one positive plasma or serum PCR result. In a preliminary run, whole-blood PCR was found to have a significantly lower sensitivity than that of plasma or serum PCR. The β-d-glucan sensitivity and specificity were 56% and 73%, respectively. |
a
EORTC/MSG, European Organization for Research and Treatment of Cancer/Mycoses Study Group; IC, invasive candidiasis; ICU, intensive care unit; IFI, invasive fungal infection; ITS, internal transcriber spacer; NA, not applicable.