Azole resistance screening in Aspergillus fumigatus sensu stricto using the azole-containing agar method (EUCAST E.Def 10.2): conidial suspension filtration and inoculum adjustment before inoculum preparation may not be needed.

Azole resistance screening in Aspergillus fumigatus sensu stricto can be routinely carried out by using azole-containing agar plates (E.Def 10.2 procedure); however, conidial suspension filtering and inoculum adjustment before inoculum preparation are time-consuming. We evaluated whether skipping the filtration and inoculum adjustment steps negatively influenced the performance of the E.Def 10.2 procedure. A. fumigatus sensu stricto isolates (n = 98), previously classified as azole susceptible or azole resistant (E.Def 9.4 method), were studied. Azole-resistant isolates had either the wild-type cyp51A gene sequence (n = 1) or the following cyp51A gene substitutions: TR34-L98H (n = 41), G54R (n = 5), TR46-Y121F-T289A (n = 1), or G448S (n = 1). In-house azole-containing agar plates were prepared according to the EUCAST E.Def 10.2 procedure. Conidial suspensions obtained by adding distilled water (Tween 20 0.1%) were either filtered and the inocula adjusted to 0.5 McFarland or left unfiltered and unadjusted. Agreements between the agar screening methods using inocula prepared by each procedure were high for itraconazole (99%), voriconazole (100%), and posaconazole (94.9%). Sensitivity and specificity (considering the susceptibility category as per the microdilution E.Def 9.4 method as the gold standard) of E.Def 10.2 were 100% to rule in or rule out resistance when unfiltered and unadjusted suspensions were used; the resistance phenotype of isolates harboring the TR34-L98H, G54R, or TR46-Y121F-T289A substitutions was correctly detected. Unfiltered and unadjusted conidial suspensions do not negatively influence the performance of the E.Def 10.2 method when screening for azole resistance in A. fumigatus sensu stricto. IMPORTANCE: Azole resistance screening in Aspergillus fumigatus sensu stricto can be routinely carried out by using azole-containing plates (E.Def 10.2 procedure); however, conidial suspension filtering and inoculum adjustment before inoculation of plates are time-consuming. We, here, showed that unfiltered and unadjusted conidial suspensions do not negatively influence the performance of the E.Def 10.2 method when screening for azole resistance in A. fumigatus sensu stricto.

Characterization of an outbreak caused by Elizabethkingia miricola using Fourier-transform infrared (FTIR) spectroscopy.

Fourier-transform infrared (FTIR) spectroscopy has the potential to be used for bacterial typing and outbreak characterization. We evaluated FTIR for the characterization of an outbreak caused by Elizabethkingia miricola. During the 2020-2021 period, 26 isolates (23 clinical and 3 environmental) were collected and analyzed by FTIR (IR Biotyper) and core-genome MLST (cgMLST), in addition to antimicrobial susceptibility testing. FTIR spectroscopy and cgMLST showed that 22 of the isolates were related to the outbreak, including the environmental samples, with only one discordance between both methods. Then, FTIR is useful for E. miricola typing and can be easily implemented in the laboratory.

Gradient diffusion strips for detecting azole resistance in Aspergillus fumigatus sensu lato.

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.

Screening of azole resistance in Aspergillus fumigatus using the EUCAST E.Def 10.2 azole-containing agar method: a single study suggests that filtration of conidial suspensions prior to inoculum preparation may not be needed.

BACKGROUND: Azole resistance screening in A. 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.

Azole-Resistant Aspergillus fumigatus Clinical Isolate Screening in Azole-Containing Agar Plates (EUCAST E.Def 10.1): Low Impact of Plastic Trays Used and Poor Performance in Cryptic Species.

Azole-containing agar is used in routine Aspergillus fumigatus azole resistance screening. We evaluated the impact of the type of plastic used to prepare in-house agar plates on the procedure's performance against A. fumigatus sensu stricto and cryptic species. A. fumigatus sensu stricto (n = 91) and cryptic species (n = 52) were classified as susceptible or resistant (EUCAST E.Def 9.3.2; clinical breakpoints v10). In-house azole-containing agar plates were prepared following EUCAST E.Def 10.1 on three types of multidish plates. We assessed the sensitivity, specificity, and agreement values of the agar plates to screen for azole resistance. Overall, sensitivity and specificity values of the agar screening method were 100% and 93.3%, respectively. The type of tray used did not affect these values. All isolates harboring TR34-L98H substitutions were classified as resistant to itraconazole and voriconazole by the agar method; however, false susceptibility (very major error) to posaconazole was not uncommon and happened in isolates with posaconazole MICs of 0.25 mg/liter. Isolates harboring G54R and TR46-Y121F-T289A substitutions were correctly classified by the agar method as itraconazole/posaconazole resistant and voriconazole resistant, respectively. False resistance (major error) occurred in isolates showing tiny fungal growth. Finally, agreements between both procedures against cryptic species were much lower. Azole-containing agar plates are a convenient and reliable tool to screen for resistance in A. fumigatus sensu stricto; the type of plastic tray used minimally affects the method. On the contrary, the performance against cryptic species is rather poor.

Spectrophotometric azole and amphotericin B MIC readings against Aspergillus fumigatus sensu lato using the EUCAST 9.3.2 methodology. Are ≥90 and ≥95% fungal growth inhibition endpoints equally suitable?

We recently reported high essential (97.1%) and categorical (99.6%) agreements between azole and amphotericin B MICs against Aspergillus fumigatus sensu lato obtained by visual and spectrophotometric readings using a ≥ 95% fungal growth endpoint and following the EUCAST methodology (doi: 10.1128/AAC.01693-20). Here, we compared the aforementioned MICs against spectrophotometric MIC readings obtained using a ≥ 90% inhibition endpoint. Spectrophotometric readings using either ≥ 90% or ≥ 95% fungal growth inhibition resulted in high categorical (>99.9%) agreements with visual MIC readings against A. fumigatus sensu stricto. In contrast, agreements with visual MICs against cryptic species were higher with the use of a ≥ 95% fungal growth inhibition endpoint. LAY SUMMARY: Spectrophotometrically obtained MIC readings using either ≥ 90% or ≥ 95% fungal growth inhibition endpoints and following the EUCAST methodology are suitable against A. fumigatus sensu stricto. However, the ≥ 95% fungal growth inhibition endpoint is preferred against cryptic species.

Azole and Amphotericin B MIC Values against Aspergillus fumigatus: High Agreement between Spectrophotometric and Visual Readings Using the EUCAST EDef 9.3.2 Procedure.

The EUCAST EDef 9.3.2 procedure recommends visual readings of azole and amphotericin B MICs against Aspergillus 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 Aspergillus fumigatussensu lato isolates. A total of 847 A. fumigatussensu lato isolates (A. fumigatus sensu stricto [n = 828] and cryptic species [n = 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 cyp51A mutants were correctly classified as resistant. Spectrophotometric determination of azole and amphotericin B MICs against A. fumigatussensu lato isolates may be a convenient alternative to visual endpoint readings.

Impact of the COVID-19 pandemic on the incidence and the epidemiology of catheter-related bloodstream infection two years later.

Introduction: The COVID-19 pandemic increased catheter-related bloodstream infections (C-RBSI), but its subsequent impact has not been adequately described. Our hospital has already depicted the effects of the COVID-19 pandemic in the first wave. However, we still do not know whether C-RBSI rates and aetiology are similar to those described before the COVID-19 pandemic. We aimed to evaluate the impact of the COVID-19 pandemic on the evolution of C-RBSI in a large tertiary teaching hospital two years later. Material and methods: We prospectively collected all confirmed C-RBSI episodes in a clinical microbiology laboratory database by matching blood cultures and catheter tip cultures with the isolation of the same microorganism (s). We compared our C-RBSI incidence rates and aetiology from 2018 to 2023. C-RBSI was defined as bacteremia or fungemia in a patient with clinical manifestations of infection and no other apparent source except the catheter. Results: During the study period, we collected 556 C-RBSI episodes. C-RBSI incidence rate per 1000 admissions each year was as follows: 2018: 2.2; 2019: 1.7; 2020: 3.29; 2021: 2.92; 2022: 2.69. and 2023: 2.01. Mainly, C-RBSI episodes occurring in critical care units each year were, respectively: 2018: 57 (54.8 %), 2019: 38 (45.2 %), 2020: 89 (63.6 %), 2021: 69 (60.5 %), 2022: 58 (50.9 %) and 2023 (61.4 %). The distribution of microorganisms showed an increase in Gram-negative episodes after the pandemic. Conclusion: Our study shows an increase in the incidence rate of C-RBSI during the COVID-19 pandemic, with a discrete decrease after that. C-RBSI episodes were mainly caused by coagulase-negative Staphylococci but with a rise in Gram-negative bacilli.

Bloodstream infections: trends and evolution of incidence and etiology in a 12-year period (2010-2021).

INTRODUCTION: The epidemiological evolution of bloodstream infections (BSIs) in the last decade is not clearly defined. Our aim was to analyze the changes in the workload in our institution and to describe the evolution of the incidence and etiology of BSIs in a 12-year period, including the COVID-19 pandemic. METHODS: All blood cultures received in the laboratory of a tertiary general hospital between 2010 and 2021 were analyzed. Bloodstream infection episodes refer to each episode of bacteremia or fungemia in each patient. Incidence rates per 1000 admissions and per 100,000 population were calculated. RESULTS: No significant changes in the incidence of BSI episodes/1000 admissions were observed (mean, 31.1), while estimated population-based incidences showed declining trends (mean, 182.8/100,000 inhabitants). There was a slight increase in BSI episodes per 1000 admissions caused by Gram-negatives (mean, 16.6/1000 admissions) and E. coli was the most frequent pathogen (mean, 8.5/1000 admissions). There was no significant rise in episodes caused by ESBL- and carbapenemase-producing E. coli or K. pneumoniae, with a decline in those caused by methicillin-resistant S. aureus. A spike in BSI episodes, fungal BSIs and catheter-related infections was detected in 2020, during the COVID-19 outbreak. CONCLUSIONS: No clear increase in the incidence of BSI episodes was detected in our center over this period. Gram-negatives are the most frequent etiology, with no clear rise in antimicrobial resistance phenotypes. The COVID-19 pandemic accounted for a small increase in BSI episodes in 2020, probably related to the increase of catheter-related infections.

The gut microbiota regulates hypothalamic inflammation and leptin sensitivity in Western diet-fed mice via a GLP-1R-dependent mechanism.

Mice lacking a microbiota are protected from diet-induced obesity. Previous studies have shown that feeding a Western diet causes hypothalamic inflammation, which in turn can lead to leptin resistance and weight gain. Here, we show that wild-type (WT) mice with depleted gut microbiota, i.e., germ-free (GF) and antibiotic-treated mice, have elevated levels of glucagon-like peptide-1 (GLP-1), are protected against diet-induced hypothalamic inflammation, and have enhanced leptin sensitivity when fed a Western diet. Using GLP-1 receptor (GLP-1R)-deficient mice and pharmacological inhibition of the GLP-1R in WT mice, we demonstrate that intact GLP-1R signaling is required for preventing hypothalamic inflammation and enhancing leptin sensitivity. Furthermore, we show that astrocytes express the GLP-1R, and deletion of the receptor in glial fibrillary acidic protein (GFAP)-expressing cells diminished the antibiotic-induced protection against diet-induced hypothalamic inflammation. Collectively, our results suggest that depletion of the gut microbiota attenuates diet-induced hypothalamic inflammation and enhances leptin sensitivity via GLP-1R-dependent mechanisms.