Rapid and reliable identification of microorganisms in the clinical laboratory is essential for an early and accurate diagnosis guiding timely therapy. However, conventional methods are sometimes ...unreliable and show controversial outcomes. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a rapid and reliable method for identification of bacteria and fungi isolated from clinical samples. Members of the genus
Raoultella
are increasingly recognized as clinically relevant. There are difficulties in their identification at the species level since sequencing the 16S rRNA or the
rpo
B genes does not show conclusive results. The aim of this study has been to compare two MALDI-TOF MS systems (Vitek MS and Bruker Biotyper) with Vitek2 and API20E systems for differentiation of
Raoultella
species. A collection of 97 clinical isolates of
Raoultella
species was identified with Vitek MS, in parallel with Vitek2 and API, and finally with Bruker Biotyper. Among the two most widely used MALDI-TOF MS platforms, results obtained with Vitek MS were slightly superior to those obtained with the Bruker Biotyper system, with sensitivities and specificities of 98.9/57.9% and 98.8/37.0%, respectively. The current commercial phenotypic identification systems are not optimized for the identification of
Raoultella
species. Our results indicate that MALDI-TOF-based identification is more accurate and sensitive than that provided by phenotypic methods.
The EUCAST EDef 9.3.2 procedure recommends visual readings of azole and amphotericin B MICs against
spp. Visual determination of MICs may be challenging. In this work, we aim to obtain and compare ...visual and spectrophotometric MIC readings of azoles and amphotericin B against
isolates. A total of 847
isolates (
= 828 and cryptic species
= 19) were tested against amphotericin B, itraconazole, voriconazole, posaconazole, and isavuconazole using the EUCAST EDef 9.3.2 procedure. Isolates were classified as susceptible or resistant/non-wild type according to the 2020 updated breakpoints. The area of technical uncertainty for the azoles was defined in the updated breakpoints. Visual and spectrophotometric (fungal growth reduction of >95% compared to the control, read at 540 nm) MICs were compared. Essential (±1 2-fold dilution) and categorical agreements were calculated. Overall, high essential (97.1%) and categorical (99.6%) agreements were found. We obtained 100% categorical agreements for amphotericin B, itraconazole, and posaconazole, and consequently, no errors were found. Categorical agreements were 98.7 and 99.3% for voriconazole and isavuconazole, respectively. Most of the misclassifications for voriconazole and isavuconazole were found to be associated with MIC results falling either in the area of technical uncertainty or within one 2-fold dilution above the breakpoint. The resistance rate was slightly lower when the MICs were obtained by spectrophotometric readings. However, all relevant
mutants were correctly classified as resistant. Spectrophotometric determination of azole and amphotericin B MICs against
isolates may be a convenient alternative to visual endpoint readings.
Background
Azole resistance screening in Aspergillus fumigatus isolates can be routinely carried out by using azole‐containing plates (E.Def 10.2 method), that requires filtering conidial suspensions ...prior inoculum adjustment.
Objectives
We evaluated whether skipping the filtration step of conidial suspensions negatively influences the performance of the E.Def 10.2.
Patients/Methods
A. fumigatus sensu stricto isolates (n = 92), classified as azole‐susceptible or azole‐resistant according to the EUCAST microdilution E.Def 9.4 method, were studied. Azole‐resistant isolates had either wild type cyp51A gene sequence (n = 3) or the TR34‐L98H (n = 26), G54R (n = 5), TR46‐Y121F‐T289A (n = 1), F46Y‐M172V‐N248T‐D255E‐E427K (n = 1), F165L (n = 1) or G448S (n = 1) cyp51A gene substitutions. In‐house azole‐containing agar plates were prepared according to the EUCAST E.Def 10.2 procedure. Conidial suspensions were obtained by adding distilled water (Tween 20 0.1%). Subsequently, the suspensions were either filtered or left unfiltered prior to inoculum adjustment to 0.5 McFarland. Using microdilution as the gold standard, agreement, sensitivity and specificity of the agar plates inoculated with two inoculums were assessed.
Results
Agreements for the agar screening method with either unfiltered or filtered conidial suspensions were high for itraconazole (100%), voriconazole (100%) and posaconazole (97.8%). Sensitivity (100%) and specificity (98.2%) of the procedure to rule in or out resistance when unfiltered suspensions were used were also high. Isolates harbouring the TR34‐L98H, G54R and TR46‐Y121F‐T289A substitutions were detected with the modified method.
Conclusions
Unfiltered conidial suspensions does not negatively influence the performance of the E.Def 10.2 method when screening for A. fumigatus sensu stricto.
Background
Studies comparing gradient diffusion strips (GDSs) and the EUCAST E.Def 9.4 microdilution method are scarce, thwarted by a low number of isolates, and restricted to selected antifungal ...agents.
Objectives
We evaluated the performance of GDSs to detect azole resistance in A. fumigatus, including cryptic species.
Patients/Methods
A. fumigatus sensu stricto (n = 89) and cryptic species (n = 52) were classified as susceptible or resistant to itraconazole, voriconazole, posaconazole and isavuconazole (EUCAST E.Def 9.4; clinical breakpoints v10). A. fumigatus sensu stricto azole‐resistant isolates had the following cyp51A gene mutations: TR34‐L98H (n = 24), G54R (n = 5), TR46‐Y121F‐T289A (n = 1), F46Y‐M172V‐N248T‐D255E‐E427K (n = 1), F165L (n = 1) and cyp51A gene wild type (n = 3). GDSs (ETEST®, bioMèrieux, Marcy‐l'Etoile, France and Liofilchem®, Roseto degli Abruzzi, Italy) MICs were obtained by following the manufacturer's guidelines.
Results
For A. fumigatus sensu stricto, itraconazole MICs >1.5 mg/L, voriconazole >0.38 mg/L, posaconazole >0.75 mg/L, and isavuconazole >0.5 mg/L correctly separated resistant from susceptible isolates with two exceptions. Considering the aforementioned cut‐off MICs, sensitivity/specificity values of GDSs to detect azole resistance were: itraconazole (97%/100%), voriconazole (97%/100%), posaconazole (97%/100%) and isavuconazole (93.3%/100%). For cryptic species isolates, voriconazole MICs >1 mg/L and isavuconazole >0.75 mg/L separated resistant isolates from susceptible isolates with 15 and 27 exceptions, respectively. Considering the aforementioned cut‐off MICs, sensitivity/specificity values were as follows: voriconazole (68.1%/100%) and isavuconazole (25%/100%). For itraconazole and posaconazole, it was not possible to establish cut‐off values.
Conclusions
We set tentative cut‐off MIC values to correctly spot resistant Aspergillus fumigatus sensu stricto isolates using GDSs. The performance against cryptic species was poor.
Non-alcoholic fatty liver disease (NAFLD) is a global health problem associated with liver morbimortality, obesity, and type 2 diabetes mellitus. This study aimed to analyze the prevalence of NAFLD ...(defined as a fatty liver index FLI ≥ 60) and its association with other cardiovascular risk (CVR) factors in patients with prediabetes and overweight/obesity. The present cross-sectional analysis uses baseline data from an ongoing randomized clinical trial. Sociodemographic and anthropometric characteristics, CVR (assessed by the REGICOR-Framingham risk equation), metabolic syndrome (MetS), and FLI-defined NAFLD (cut-off value of ≥60) were assessed. The prevalence of FLI-defined NAFLD was 78% overall. Men exhibited a worse cardiometabolic profile as compared to women, specifically, with higher values of systolic blood pressure (137.02 ± 13.48 vs. 131.22 ± 14.77 mmHg), diastolic blood pressure (85.33 ± 9.27 vs. 82.3 ± 9.12 mmHg), aspartate aminotransferase (AST) (27.23 ± 12.15 vs. 21.23 ± 10.05 IU/L), alanine aminotransferase (ALT) (34.03 ± 23.31 vs. 21.73 ± 10.80 IU/L), and higher CVR (5.58 ± 3.16 vs. 3.60 ± 1.68). FLI-defined NAFLD was associated with elevated AST, ALT, and the presence of MetS (73.7%) and CVR for the whole sample. People with prediabetes present a high burden of comorbidities related to CVR, despite clinical follow-up, and it is recommended to actively begin working with them to reduce their risks.
We aimed to assess the percentage of azole resistance in Aspergillus fumigatus in Spain.
Thirty participating Spanish hospitals stored all morphologically identified A. fumigatus sensu lato clinical ...isolates—regardless their clinical significance—from 15 February to 14 May 2019. Isolates showing azole resistance according to the EUCAST 9.3.2 methodology were molecularly identified and the cyp51A gene was studied in A. fumigatus sensu stricto isolates.
Eight hundred and forty-seven isolates from 725 patients were collected in 29 hospitals (A. fumigatus sensu stricto (n = 828) and cryptic species (n = 19)). Isolates were mostly from the lower respiratory tract (94.0%; 797/847). Only cryptic species were amphotericin B resistant. Sixty-three (7.4%) out of the 847 isolates were resistant to ≥1 azole(s). Azole resistance was higher in cryptic species than in A. fumigatus sensu stricto (95%, 18/19 vs. 5.5%, 45/828); isavuconazole was associated to the lowest number of non-wild type isolates. The dominant mechanism of resistance was the presence of TR34-L98H substitutions (n = 24 out of 63). Out of the 725 patients, 48 (6.6%) carried either cryptic species (n = 14) or A. fumigatus sensu stricto (n = 34; 4.7%) resistant isolates. Aspergillus fumigatus sensu stricto harbouring either the TR34-L98H (n = 19) or TR46/Y121F/T289A (n = 1) mutations were detected in patients in hospitals located at 7/24 studied cities.
Of the patients, 6.6% carry azole-resistant A. fumigatus sensu lato isolates in Spain. TR34-L98H is the dominant cyp51A gene substitutions, although its presence is not widespread.
The main goal of this study was to accurately detect azole resistance in species of the Aspergillus fumigatus complex by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry ...(MALDI-TOF MS).
Identification of isolates (n = 868) was done with MALDI-TOF MS using both commercial and in-house libraries. To determine azole susceptibility, the EUCAST E.Def. 9.3.2 method was applied as the reference standard. Identification of resistant isolates was confirmed by DNA sequence analysis. Protein spectra obtained by MALDI-TOF MS were analysed to differentiate species within the A. fumigatus complex and to detect azole-resistant A. fumigatus sensu stricto isolates.
Correct discrimination of A. fumigatus sensu stricto from cryptic species was accomplished in 100% of the cases applying principal component analysis (PCA) to protein spectra generated by MALDI-TOF MS. Furthermore, a specific peak (4586 m/z) was found to be present only in cryptic species. The application of partial least squares (PLS) discriminant analysis allowed 98.43% (±0.038) discrimination between susceptible and azole-resistant A. fumigatus sensu stricto isolates. Finally, based on PLS and SVM, A. fumigatus sensu stricto isolates with different cyp51A gene mutations were correctly clustered in 91.5% of the cases.
MALDI-TOF MS combined with peak analysis is a novel tool that allows the differentiation of A. fumigatus sensu stricto from other species within the A. fumigatus complex, as well as the detection of azole-resistant A. fumigatus sensu stricto. Although further studies are still needed, the results reported here show the great potential of MALDI-TOF and machine learning for the rapid detection of azole-resistant Aspergillus fumigatus isolates from clinical origins.
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