Antifungal susceptibility testing practices in mycology laboratories in France, 2018.

A survey of mycology laboratories for antifungal susceptibility testing (AFST) was undertaken in France in 2018, to better understand the difference in practices between the participating centers and to identify the difficulties they may encounter as well as eventual gaps with published standards and guidelines. The survey captured information from 45 mycology laboratories in France on how they perform AFST (number of strains tested, preferred method, technical and quality aspects, interpretation of the MIC values, reading and interpretation difficulties). Results indicated that 86% of respondents used Etest as AFST method, with a combination of one to seven antifungal agents tested. Most of the participating laboratories used similar technical parameters to perform their AFST method and a large majority used, as recommended, internal and external quality assessments. Almost all the participating mycology laboratories (98%) reported difficulties to interpret the MIC values, especially when no clinical breakpoints are available. The survey highlighted that the current AFST practices in France need homogenization, particularly for MIC reading and interpretation.

Comparison of the MICs Obtained by Gradient Concentration Strip and EUCAST Methods for Four Azole Drugs and Amphotericin B against Azole-Susceptible and -Resistant Aspergillus Section Fumigati Clinical Isolates.

Reference methods used to assess the drug susceptibilities of Aspergillus fumigatus isolates consisted of EUCAST and CLSI standardized broth microdilution techniques. Considering the increasing rate and the potential impact on the clinical outcome of azole resistance in A. fumigatus, more suitable techniques for routine testing are needed. The gradient concentration strip (GCS) method has been favorably evaluated for yeast testing. The aim of this study was to compare the CGS test with EUCAST broth microdilution for amphotericin B (AMB), posaconazole (PCZ), itraconazole (ITZ), voriconazole (VRZ), and isavuconazole (ISA). A total of 121 Aspergillus section Fumigati strains were collected, including 24 A. fumigatus sensu stricto strains that were resistant to at least one azole drug. MICs were determined using GCS and EUCAST methods. Essential agreement between the 2 methods was considered when MICs fell within ±1 dilution or ±2 dilutions of the 2-fold dilution scale. Categorical agreement was defined as the percentage of strains classified in the same category (susceptible, intermediate, or resistant) with both methods. Essential agreements with ±1 dilution and ±2 dilutions were 96.7, 93.4, 90.0, 89.3, and 95% and 100, 99.2, 100, 97.5, and 100% for AMB, PCZ, ITZ, VRZ, and ISA, respectively. Categorical agreements were 94.3, 86.1, 89.3, and 88.5% for AMB, PCZ, ITZ, and VRZ, respectively. Detection of resistance was missed with the GCS for one strain (4.1%) for PCZ and for 2 strains (8.3%) for ISA. Determination of ITZ MICs using the GCS allowed the detection of 91.7% of azole-resistant strains. The GCS test appears to be a valuable method for screening azole-resistant A. fumigatus clinical isolates.

In Vitro Susceptibility of Fusarium to Isavuconazole.

To evaluate the in vitro susceptibility of Fusarium to isavuconazole, 75 clinical isolates were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry and then tested with a broth microdilution method (EUCAST) and the gradient concentration strip (GCS) technique. The activity of isavuconazole overall was shown to be limited, with an MIC50 of >16 µg/ml, without significant differences between the species complexes. The categorical agreement between GCS and EUCAST was 97.4% to 100%, making the GCS as a valuable alternative.

Usefulness of ß-D-glucan for diagnosis and follow-up of invasive candidiasis in onco-haematological patients.

OBJECTIVES: Definitive diagnosis of invasive candidiasis (IC) may be difficult to achieve in patients with haematological malignancy (PHM). We aimed to evaluate the performance of BDG for the diagnosis and the follow-up of IC in PHM. PATIENTS AND METHODS: We retrospectively reviewed the serological data of BDG assay in adult and paediatric PHM, who developed candidemia or chronic disseminated candidiasis (CDC) through a 4-year period. Sensitivity and kinetics of BDG were determined for both clinical forms. RESULTS: In a panel of 3027 PHM, incidence rates of candidemia and CDC ranged between 0.74 and 0.77 and 0.30 and 0.44 according to the group of patients. At the time of diagnosis, 43.5% and 73% of cases of candidemia and CDC had a positive BDG assay, respectively. We found a significant correlation between the level of BDG at diagnosis and the outcome of candidemia (p = 0.022). In all cases of CDC, BDG negative results were obtained 2 to 6 months before recovery of the CT-scan lesions. CONCLUSIONS: BDG exhibits a low sensitivity to detect IC in PHM, but its kinetics correlates the clinical outcome. Additional studies are warranted in patients with CDC to evaluate the interest of monitoring BDG levels to anticipate the discontinuation of antifungal maintenance therapy.

Cryptococcal antigen detection in broncho-alveolar lavage fluid.

Cryptococcal antigen (CryAg) testing in serum and CSF is a clue diagnostic tool for cryptococcosis. In this study, we reviewed the performances of the CryAg detection (Premier EIA, Meridian) routinely performed in broncho-alveolar lavage fluid (BALF) during a 7-year period (2007-2013). CryAg was detected in 12 cases among 4650 BALF analyzed, while positive culture from BALF was detected in nine cases. We found sensitivity, specificity, positive and negative predictive values at 0.44-0.80 (according to the radio-clinical form), 0.99, 0.36, and 0.99, respectively. These results do not support the routine use of the test in BALF.

Evaluation of a rapid enzyme-linked immunosorbent assay for diagnosis of strongyloidiasis.

Diagnosis of strongyloidiasis using stool examination remains unsatisfactory due to the lack of sensitivity and fastidious techniques. In this work, we investigated the value of an anti-Strongyloides IgG enzyme immunoassay (EIA), using a panel of 207 sera retrospectively collected from patients with definitive diagnoses of strongyloidiasis (n=57), other helminthic infections (n=46), eosinophilia without parasitic infection diagnosis (n=54), and digestive disturbances following a tropical journey (n=30) and from 20 negative controls. By following a receiver operating characteristic (ROC) curve analysis, it was possible to optimize the test to reach a sensitivity of 91.2% and a specificity of 93.3%, with 92.8% of patients correctly classified. Considering the incidence of strongyloidiasis diagnosed in our own laboratory, the negative predictive value was calculated at 99.9%. In conclusion, this test is very rapid and easy to perform and may be valuable for diagnosis of strongyloidiasis both in cases where the infection is unrevealed by a parasitological stool examination and in patients at risk for severe clinical forms, such as patients receiving immunosuppressive therapy.