Wiebke Duettmann

Performance of Galactomannan, Beta-d-Glucan, Aspergillus Lateral-Flow Device, Conventional Culture, and PCR Tests with Bronchoalveolar Lavage Fluid for Diagnosis of Invasive Pulmonary Aspergillosis

ABSTRACT Galactomannan detection in bronchoalveolar lavage (BAL) fluid samples (GM test) is currently considered the gold standard test for diagnosing invasive pulmonary aspergillosis (IPA). The limitations, however, are the various turnaround times and availability of testing. We compared the performance of GM testing with that of conventional culture, an Aspergillus lateral-flow-device (LFD) test, a beta-d-glucan (BDG) test, and an Aspergillus PCR assay by using BAL fluid samples from immunocompromised patients. A total of 78 BAL fluid samples from 78 patients at risk for IPA (74 samples from Graz and 4 from Mannheim) collected between December 2012 and May 2013 at two university hospitals in Austria and Germany were included. Three patients had proven IPA, 14 probable IPA, and 17 possible IPA, and 44 patients had no IPA. The diagnostic accuracies of the different methods for probable/proven IPA were evaluated. The diagnostic odds ratios were the highest for the GM, PCR, and LFD tests. The sensitivities for the four methods (except culture) were between 70 and 88%. The combination of the GM (cutoff optical density index [ODI], >1.0) and LFD tests increased the sensitivity to 94%, while the combination of the GM test (>1.0) and PCR resulted in 100% sensitivity (specificity for probable/proven IPA, 95 to 98%). The performance of conventional culture was limited by low sensitivity, while that of the BDG test was limited by low specificity. We evaluated established and novel diagnostic methods for IPA and found that the Aspergillus PCR, LFD, and GM tests were the most useful methods for diagnosing the disease by using BAL fluid samples. In particular, the combination of the GM test and PCR or, if PCR is not available, the LFD test, allows for sensitive and specific diagnosis of IPA.

Potential Factors for Inadequate Voriconazole Plasma Concentrations in Intensive Care Unit Patients and Patients with Hematological Malignancies

ABSTRACT Voriconazole plasma concentrations (VPCs) vary widely, and concentrations outside the therapeutic range are associated with either worse outcome in invasive aspergillosis (IA) or increased toxicity. The primary goal of this cohort study conducted in a real-life setting was to identify potential factors associated with inadequate VPCs in ICU patients and patients with hematological malignancies. Within a period of 12 months, trough VPCs were obtained and analyzed with high-performance liquid chromatography, and the adequate range was defined as 1.5 to 5.5 mg/liter. VPCs of <1.5 mg/liter were defined as low, whereas VPCs of >5.5 mg/liter were defined as potentially toxic. A total of 221 trough VPCs were obtained in 61 patients receiving voriconazole, and 124/221 VPCs (56%) were found to be low. Multivariate analysis revealed that low VPCs were significantly associated with clinical failure of voriconazole, prophylactic use, younger age, underlying hematological malignancy, concomitant proton pump inhibitor (PPI) (pantoprazole was used in 88% of the patients), and absence of side effects. Low VPCs remained an independent predictor of clinical failure of voriconazole. The defined adequate range was reached in 79/221 (36%) VPCs. In 18 samples (8%), potentially toxic levels were measured. Multivariate analysis revealed higher body mass index (BMI), absence of hematological malignancy, therapeutic application, and diarrhea as factors associated with potentially toxic VPCs. Neurotoxic adverse events occurred in six patients and were mostly associated with VPCs in the upper quartile of our defined adequate range. In conclusion, potential factors like younger age, prophylaxis, underlying hematological malignancy, BMI, and concomitant PPI should be considered within the algorithm of voriconazole treatment.

Sensitivity of galactomannan enzyme immunoassay for diagnosing breakthrough invasive aspergillosis under antifungal prophylaxis and empirical therapy

Data on diagnostic performance of Galactomannan (GM) testing in patients under mould‐active regimens are limited. Whether sensitivity of GM testing for diagnosing breakthrough invasive aspergillosis (IA) is decreased under antifungal prophylaxis/therapy remains therefore a point of discussion. We retrospectively analysed GM test results in patients who were admitted with underlying haematological malignancies to two Divisions of the Medical University Hospital of Graz, Austria, between 2009 and 2012. Only cases of probable and proven IA that were diagnosed by other methods than GM testing were included (time of diagnosis = day 0). We compared GM results of patients with/without therapy/prophylaxis for the period of 2 weeks prior (week −2) until 3 weeks postdiagnosis. A total of 76 GM test results in nine patients were identified. Six patients had received antifungal therapy/prophylaxis from week −2, whereas three patients were treated with therapy from the time of diagnosis at week 0. GM testing was positive in 45/76 (59%) of samples. Sensitivity of GM testing for detection of proven or probable IA at week −1 and 0 was 77% and 79% in patients with mould‐active regimens. We conclude that GM testing might be a useful diagnostic method for breakthrough IA in patients receiving mould‐active prophylaxis/therapy.

Impact of structured personal on-site patient education on low posaconazole plasma concentrations in patients with haematological malignancies

Low posaconazole plasma concentrations (PPCs) are associated with breakthrough invasive mould infections among patients with haematological malignancies. This study evaluated the influence of structured personal on-site patient education on low PPCs. The study was conducted from July 2012 to May 2013 at the Division of Hematology, Medical University Hospital of Graz (Graz, Austria). PPCs were measured in all patients with haematological malignancies receiving the drug prophylactically. Concentrations above the target of 0.5 mg/L were defined as satisfactory and those below this concentration as low. In patients with low PPCs, structured personal on-site education regarding the intake of posaconazole (e.g. intake with fatty/acid food, prevention of nausea and vomiting) was performed. In total, 258 steady-state PPCs were measured in 65 patients [median PPC 0.59 mg/L, interquartile range 0.25-0.92 mg/L; 141/258 (54.7%) satisfactory]. Diarrhoea was the strongest predictor of low PPCs in the multivariate analysis. Initial steady-state PPCs were sufficient in 29 patients and low in 36 patients. Of the 36 patients with low initial steady-state PPCs, 8 were either discharged or antifungal therapy was modified before a follow-up PPC was obtained; in the remaining 28 patients, personal on-site education was performed. In 12/28 patients (43%) the personal on-site education led to sufficient levels, whilst in 16 (57%) PPCs stayed below the target, although increasing from <0.2 mg/L to >0.3 mg/L in 6 of these patients. In conclusion, personal education appears to be a promising tool to increase low PPCs.

Clinical evaluation of the newly formatted lateral-flow device for invasive pulmonary aspergillosis

The study evaluated the newly formatted Aspergillus‐specific lateral‐flow‐device (LFD), and compared its performance to the original prototype “old” LFD test using BALF samples from 28 patients (14 patients with probable/proven invasive pulmonary aspergillosis [IPA] and 14 patients with no evidence for IPA). A total of 10/14 (71%) of BALF samples from patients with probable/proven IPA resulted positive with the new LFD, including 8/9 with true‐positive and 2/5 with false‐negative results with the old LFD. All 14 samples from patients without IPA resulted negative with the new LFD; specificity of the new LFD was significantly improved compared to the old LFD.

Posaconazole Plasma Concentrations on Days Three to Five Predict Steady-State Levels.

ABSTRACT Low posaconazole plasma concentrations (PPCs) have been associated with breakthrough invasive fungal infections. We assessed the correlation between pre-steady-state PPCs (obtained between days 3 and 5) and PPCs obtained during steady state in 48 patients with underlying hematological malignancies receiving posaconazole oral-solution prophylaxis. Pre-steady-state PPCs correlated significantly with PPCs obtained at steady state (Spearman r = 0.754; P < 0.001). Receiver operating characteristic (ROC) curve analysis of pre-steady-state PPCs revealed an area under the curve (AUC) of 0.884 (95% confidence interval [CI], 0.790 to 0.977) for predicting satisfactory PPCs at steady state.

Detection of (1→3)‐β‐D‐glucan in same‐day urine and serum samples obtained from patients with haematological malignancies

Serum 1,3‐beta‐d‐glucan (BDG) testing is an established diagnostic marker for invasive fungal infections (IFI) among patients with haematological malignancies. In contrast limited data exist regarding the application of urine BDG testing. Same‐day midstream urine and serum screening samples were collected in adult patients with underlying haematological malignancies. A total of 80 urine samples from 46 patients were investigated: Twenty‐six had positive corresponding serum BDG >120 pg ml−1, 27 intermediate (60–80 pg ml−1), and 27 negative serum BDG (<25 pg ml−1). A significant positive correlation between BDG in serum and urine samples was observed (P = 0.025; r = 0.252). Sensitivity, specificity, positive predictive value and negative predictive value (compared with same‐day serum results) were: 42%, 76%, 46%, 73% when using an 80 pg ml−1 urine cut‐off, and 35%, 96%, 82%, 75% for a 250 pg ml−1 cut‐off. Urine BDG seemed to be higher in samples obtained from patients with probable IFI (n = 13, median 145, IQR 22–253) compared to those from patients without IFI (n = 56, median 24, IQR 15–88) but the difference was not significant (P = 0.069). Overall correlation of same‐day urine BDG and serum BDG was moderate. However, urine BDG testing may warrant further investigation in larger studies, as high‐positive urine results correlated with high‐positive corresponding serum levels and clinical performance was comparable to serum BDG.

Specificity of mannan antigen and anti-mannan antibody screening in patients with haematological malignancies at risk for fungal infection

Combination of mannan antigen and anti‐mannan antibody (Mn/A‐Mn) testing has been reported a useful and specific strategy for diagnosis of invasive Candida infections (ICIs). We evaluated Mn/A‐Mn as a screening tool in patients with haematological malignancies. This clinical prospective study was performed at the Division of Hematology, Medical University Graz, Austria between July and December 2012. Patients at risk for fungal infection were included into the study and twice weekly screened by Mn/A‐Mn testing, yielding 650 samples. Of overall 67 patients 66 had no evidence for ICI. From those, 153/640 serum samples (23.9%) were positive for mannan Ab, and nine (1.4%) for Ag. Most false positive Ab results were observed among 375 samples from patients without haematopoietic stem cell transplantation (34.9% resulted positive). Combined specificity of Mn/A‐Mn was 74.8%. Of 10 samples obtained in the single patient with candidemia, five were positive for mannan Ag (from the day of diagnosis up to 40 days after detection of candidemia) and none for Ab. In conclusion, mannan Ab screening yielded a high number of false positive results. While mannan Ag was found to be highly specific and may have potential for diagnostic driven testing, mannan Ab testing cannot be recommended based on our study results.

Detection of central venous catheter-related bloodstream infections in haematooncological patients

Catheter‐related bloodstream infections (CRBSIs) are currently detected in patients with clinically suspicion. The aim of our study was to evaluate whether CRBSIs could be anticipated and detected in a subclinical stage by peptide nucleic acid fluorescence in situ hybridization (PNA FISH) using universal hybridization probes or acridine orange leucocyte cytospin (AOLC) tests in haematooncological patients with central venous catheters (CVCs) in situ.