Performance of an antigen-antibody combined assay for hepatitis C virus testing without venipuncture.

BACKGROUND: Hepatitis C virus (HCV) is underdiagnosed and therefore increasing the opportunities for HCV testing without venipuncture may be useful. OBJECTIVES: We evaluated the analytical performance of a modified, commercially available, combined HCV antigen-antibody assay (cEIA) (Monolisa(®) HCV-Ag-Ab-ULTRA) and a commercially available point-of-care (POC) device (OraQuick(®) HCV) on fingerstick blood (FSB) and oral mucosal transudate (OMT). STUDY DESIGN: FSB, OMT and serum samples were collected from 113 cases of HCV-antibody-positive patients and 88 HCV-antibody-negative controls. The HCV-antibody-positive group included 63 patients with quantifiable HCV-RNA (56%) and 17 HIV/HCV co-infected patients (15%). FSB and OMT specimens were collected as dried blood spots (DBSs) or with the OraSure collection system, before testing with cEIA. RESULTS: With FSB specimens, the cEIA and the POC device exhibited 100% specificity and 98.2% and 97.4% sensitivity, respectively. The specificity of the cEIA in FSB sharply decreased if stored 3days at room temperature. With OMT specimens, the cEIA sensitivity (71.7%) and specificity (94.3%) were significantly lower than the performance of OraQuick(®) HCV (sensitivity, 94.6%; specificity, 100%). The optical densities obtained with the cEIA in FSB and OMT were lower in HIV/HCV co-infected patients compared with HCV monoinfected patients. CONCLUSION: The cEIA using FSB specimens collected on DBSs preserved in appropriate storage conditions was a reliable alternative, equivalent to the POC assay, for HCV testing without venipuncture. The cEIA was not adapted for HCV testing on OMT.

Susceptibility of 100 filamentous fungi: comparison of two diffusion methods, Neo-Sensitabs and E-test, for amphotericin B, caspofungin, itraconazole, voriconazole and posaconazole.

We compared the E-test method to that of the Neo-Sensitabs tablet diffusion assay for evaluating the in vitro susceptibility of 100 clinical isolates of filamentous fungi (Aspergillus spp., Fusarium spp., Scedosporium spp., zygomycetes and other molds) to amphotericin B, itraconazole, voriconazole, caspofungin, and posaconazole. We determined the categorical agreement level between E-test minimum inhibitory concentrations (MIC) and tablet end-points, as opposed to the following disagreement parameters: very major error - resistant parameter (R) in E-test and susceptible (S) in tablet; major error - S by E-test and R by tablet; minor error - shifts between S and susceptible dose-dependent (S-DD) or S-DD and R. We also performed linear regression analyses and computed Pearson's correlation coefficients (R values) between the log transforms of MICs and the inhibition zone diameters of the five studied antifungal agents. For itraconazole we obtained 97% categorical agreement and R = -0.727. Categorical agreement for caspofungin and voriconazole was 96% and R =-0.821 and R = -0.789, respectively. For posaconazole the categorical agreement was 94% and R =-0.743. Amphotericin B exhibited a lower degree of agreement (76%, R = -0.672), especially in studies of Aspergillus spp. Our results suggest a potential value of the Neo-Sensitabs assay for in vitro susceptibility testing of molds to itraconazole, voriconazole, caspofungin and posaconazole, while amphotericin B exhibited an overall lower degree of agreement.