Reactivity of the 1,3-ß-D-glucan assay during bacteraemia: limited evidence from a prospective study.

There are discrepancies in the retrospective studies published in literature of whether or not bacteraemia could lead to false positivity of 1,3-ß-D (BG) glucan assay. We performed, for the first time, a prospective study evaluating the role of bacterial bloodstream infection to the reactivity of BG assay. Twenty-six episodes of bacteraemia that occurred in high-risk haematological patients were included in our study. Consecutive BG levels >80 pg ml(-1) were required for test positivity. Only 2 of 26 patients were BG positive - both with IFDs. Thus, we prospectively did not prove bacteraemia as the source of cross reactivity of BG assay in haematological patients.

Monitoring trough voriconazole plasma concentrations in haematological patients: real life multicentre experience.

The objective of this retrospective study was to evaluate results from voriconazole therapeutic drug monitoring (TDM) in haematological patients in routine clinical practice. Between 2005 and 2010, 1228 blood samples were obtained from 264 haematological patients (median 3 samples/patient; range 1-27) receiving voriconazole for targeted/preemptive treatment of invasive aspergillosis (IA) (46.3% of samples), empirical therapy (12.9%) or prophylaxis (40.8%). A high-pressure liquid chromatography assay was used to analyse voriconazole concentrations. Clinical and laboratory data were analysed retrospectively. The median of the detected voriconazole plasma concentration was 1.00 µg ml(-1) (range <0.20-13.47 µg ml(-1)). Significant inter- and intra-patients variability of measured concentrations (81.9% and 50.5%) were identified. With the exception of omeprazole administration, there was no relevant relationship between measured voriconazole concentrations and drug dose, route administration, age, gender, CYP2C19*2 genotype, gastrointestinal tract abnormality, administration via nasogastric tube, serum creatinine, and liver enzymes. However, per patient analysis identified significant role of individual voriconazole dose and drug form change on measured plasma concentration. Measured voriconazole concentrations did not correlate with the treatment outcome of patients with IA. We only identified a limited number of adverse events related to voriconazole therapy; however, the median plasma concentration was not different from concentrations measured in samples without reported toxicity. Our retrospective study has suggested that routine monitoring of voriconazole plasma concentrations has probably only a limited role in daily haematological practice.

Galactomannan detection in bronchoalveolar lavage fluid for the diagnosis of invasive aspergillosis in patients with hematological diseases-the role of factors affecting assay performance.

BACKGROUND: We evaluated the performance of a galactomannan (GM) assay in bronchoalveolar lavage (BAL) fluid compared to serum samples for the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with hematological diseases. METHODS: Two hundred and fifty-five bronchoscopies were performed on 230 patients. Bronchial and alveolar samples from BAL fluid as well as serum samples were analyzed in the GM assay. RESULTS: Twenty-eight cases of IPA (11%) were diagnosed. The sensitivity, specificity, positive predictive value, and negative predictive value of the GM assay using a cut-off of 0.5 were 57.1%, 99.3%, 94.1%, and 92.5%, respectively, for the alveolar sample; 44.0%, 99.3%, 91.7%, and 91.4%, respectively, for the bronchial sample; and 60.7%, 100%, 100%, and 92.9%, respectively, for serum. The highest sensitivity (78.6%) with good specificity (98.6%) was obtained with a 'triple detection' of GM in bronchial, alveolar, and serum samples. Neutropenia and antifungal therapy for only 24h increased the sensitivity, while antifungal treatment for ≥ 2 days decreased assay performance. Moreover, a trend towards a higher volume of aspirated fluid in GM-negative BAL (p=0.092) was observed. CONCLUSIONS: In contrast to recently published data, we found only moderate sensitivity, but high specificity and high positive predictive value of the detection of GM in BAL fluid. In addition, neutropenia, antifungal therapy, and BAL standardization affected GM assay performance.

Rapid detection and identification of mucormycetes from culture and tissue samples by use of high-resolution melt analysis.

We present a method for rapid and simple detection of clinically relevant mucormycetes of the Mucorales order in cultures and clinical samples. This seminested real-time PCR uses mucormycete-specific primers and is followed by species identification using high-resolution melt (HRM) analysis. The method is highly suitable for routine clinical diagnostics.

Difficulties in using 1,3-{beta}-D-glucan as the screening test for the early diagnosis of invasive fungal infections in patients with haematological malignancies--high frequency of false-positive results and their analysis.

We have evaluated the contribution of the 1,3-beta-d-glucan (BG) assay for the screening of invasive fungal infections (IFIs) in patients with haematological malignancies. Serum samples from patients at risk of IFI were collected twice a week and retrospectively tested using the BG assay. BG screening was performed on 1143 samples from 91 patients during 104 anticancer treatment cycles. Proven and probable cases of IFI occurred in 9 (8.7 %) treatment cycles. Depending on the criterion of positivity used (1x >60 pg ml(-1), 1x >80 pg ml(-1), 2x >60 pg ml(-1) or 2x >80 pg ml(-1)) the sensitivity and specificity were 89, 89, 67 and 44 %, and 20, 48, 33 and 56 %, respectively. Although the test was marked as positive in 82, 68, 54 and 45 % of all the treatment cycles, in the majority of cases, these positivities were probably false. The major limit of the BG test was an extremely low positive predictive value (10 to 12 %). We have analysed mucositis, candida colonization, bacteraemia, use of antimicrobials, erythrocyte and thrombocyte filtered blood products, collecting tubes or sampling via venous catheters. Even though no factor is a major source of BG, it could at least partially influence BG assay performance. Thus, BG detection has a limited usefulness as a screening method for IFIs in patients with haematological malignancies.

[Contribution of galactomannan antigen detection to early diagnosis of invasive aspergillosis]. / Vyuzití detekce galaktomannanu pro casnou diagnostiku invazivní aspergilózy.

Invasive aspergillosis is a serious and often lethal fungal infection in immunocompromised patients, with increasing incidence in recent years. The high mortality is related not only to severe immunosuppression but especially to difficulties in early diagnosis. The development of noninvasive nonculture diagnostic methods in recent years is a major advance in the early diagnosis of invasive aspergillosis, but the only method with a clear position is currently galactomannan detection by sandwich ELISA. The test has an excellent negative predictive value and is able to exclude invasive aspergillosis with high probability. In addition, its good sensitivity often allows diagnosis of the condition before it is clinically manifested. However, variations in sensitivity due to numerous factors and potential false-positive results in certain populations are the main limitations to its use. The purpose of this review is to summarize the current knowledge of the use of galactomannan in the early diagnosis of invasive aspergillosis.