Dataset Information

Spectrophotometric detection of azole-resistant Aspergillus fumigatus with the EUCAST broth microdilution method: is it time for automated MIC reading of EUCAST antifungal susceptibility testing of Aspergillus species?

ABSTRACT:

Objectives

Current reference susceptibility testing methods of Aspergillus require visual reading, which is subjective and necessitates experienced staff. We compared spectrophotometric and visual MIC reading of EUCAST E.Def 9.3.2 susceptibility testing of Aspergillus fumigatus for a large collection of isolates with different azole resistance mechanisms.

Methods

A. fumigatus (n = 200) were examined, including 62 WT and 138 non-WT with the following alterations: TR34/L98H (n = 57), TR46/Y121F/T289A (n = 54) or single point mutations (n = 27). EUCAST E.Def 9.3.2 susceptibility testing was performed for amphotericin B, itraconazole, voriconazole, posaconazole and isavuconazole. MICs were determined after 48 h of incubation visually and spectrophotometrically, as the lowest concentration corresponding to a 1%, 3%, 5%, 10% or 15% OD increase above the background OD. The best spectrophotometric endpoint (SPE) was identified based on the highest essential agreement (EA; ±1 two-fold dilution) and categorical agreement (CA) and fewer very major errors (VMEs) and major errors (MEs).

Results

Τhe best SPEs were 5% and 10% for all drugs. The best agreement between visual and spectrophotometric MICs was found with the 10% growth endpoint, which resulted in identical median MICs with 90% of differences being ≤1 two-fold and higher EA (91%-100%) and CA (100%) and no VMEs and MEs compared with the 5% endpoint (77%-100%, 96%-98%, 0% and 0%-4%, respectively).

Conclusions

Spectrophotometric MIC reading can be used for A. fumigatus susceptibility testing and for detecting azole resistance. A visual inspection of the plate should be performed to confirm equal inoculation, absence of well contamination and proper growth, and to identify potential uncommon phenotypes or subpopulations.

SUBMITTER: Meletiadis J

PROVIDER: S-EPMC9840474 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Spectrophotometric detection of azole-resistant Aspergillus fumigatus with the EUCAST broth microdilution method: is it time for automated MIC reading of EUCAST antifungal susceptibility testing of Aspergillus species?

Meletiadis Joseph J Efstathiou Ioanna I van der Lee Hein A L HAL Astvad Karen M T KMT Verweij Paul E PE Arendrup Maiken Cavling MC

The Journal of antimicrobial chemotherapy 20220401 5

<h4>Objectives</h4>Current reference susceptibility testing methods of Aspergillus require visual reading, which is subjective and necessitates experienced staff. We compared spectrophotometric and visual MIC reading of EUCAST E.Def 9.3.2 susceptibility testing of Aspergillus fumigatus for a large collection of isolates with different azole resistance mechanisms.<h4>Methods</h4>A. fumigatus (n = 200) were examined, including 62 WT and 138 non-WT with the following alterations: TR34/L98H (n = 57) ...[more]

PMID: 35194639

Similar Datasets

Project description:The performance of the Liofilchem Compact Antimicrobial Susceptibility Panel (ComASP) Cefiderocol was evaluated in a multicenter study. Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa clinical isolates and challenge isolates were tested by three and one sites, respectively. Minimum inhibitory concentration (MIC) testing was performed by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution and ComASP, which included two reading endpoints (CLSI read; MIC is the first well in which reduction of growth is <1 mm or light haze/faint turbidity] and ComASP [ComASP read; MIC is the first well at which 100% inhibition of growth occurs]). Each site performed reproducibility and quality control (QC) by ComASP and broth microdilution (BMD). Reproducibility was excellent (97.4% within ±1 dilution of modal MIC). All QC results were within CLSI QC ranges by BMD and ComASP, except for two E. coli ATCC 25922 results from one site. Essential agreement for combined clinical and challenge Enterobacterales was 84.3% (CLSI read) and 95.7% (ComASP read), P. aeruginosa was 83.3% (CLSI read) and 93.7% (ComASP read), and A. baumannii was 78.3% (CLSI read) and 96.7% (ComASP read). Categorical agreement for Enterobacterales was 92.4% for both CLSI read and ComASP read, for P. aeruginosa was 89.7% (CLSI read) and 92.1% (ComASP read), and for A. baumannii was 72.8% (CLSI read) and 91.3% (ComASP read). There were no very major errors using the ComASP read. One very major error for P. aeruginosa occurred using the CLSI read method. Three very major errors for A. baumannii occurred using the CLSI read method. ComASP Cefiderocol was shown to be a reliable method for testing cefiderocol MIC against relevant clinical isolates when ComASP read is used.ImportanceThere are very limited commercial methods available to clinical laboratories for cefiderocol minimum inhibitory concentration (MIC) testing. The Compact Antimicrobial Susceptibility Panel (ComASP) Cefiderocol method includes iron-depleted cation-adjusted Mueller-Hinton broth, which eliminates variability in cefiderocol MIC results based on iron levels. The lyophilized multi-well format of ComASP also provides for room temperature storage. In comparison to what an individual lab may do for method verification, this multi-site, multi-isolate study provides a robust evaluation and greater assurance to clinical microbiologists of the method's accurate and reproducible performance.

Project description:Aspergillus fumigatus is an opportunistic human pathogen that causes aspergillosis, a spectrum of environmentally acquired respiratory illnesses. It has a cosmopolitan distribution and exists in the environment as a saprotroph on decaying plant matter. Azoles, which target Cyp51A in the ergosterol synthesis pathway, are the primary class of drugs used to treat aspergillosis. Azoles are also used to combat plant pathogenic fungi. Recently, an increasing number of azole-naive patients have presented with pan-azole-resistant strains of A. fumigatus. The TR34/L98H and TR46/Y121F/T289A alleles in the cyp51A gene are the most common ones conferring pan-azole resistance. There is evidence that these mutations arose in agricultural settings; therefore, numerous studies have been conducted to identify azole resistance in environmental A. fumigatus and to determine where resistance is developing in the environment. Here, we summarize the global occurrence of azole-resistant A. fumigatus in the environment based on available literature. Additionally, we have created an interactive world map showing where resistant isolates have been detected and include information on the specific alleles identified, environmental settings, and azole fungicide use. Azole-resistant A. fumigatus has been found on every continent, except for Antarctica, with the highest number of reports from Europe. Developed environments, specifically hospitals and gardens, were the most common settings where azole-resistant A. fumigatus was detected, followed by soils sampled from agricultural settings. The TR34/L98H resistance allele was the most common in all regions except South America where the TR46/Y121F/T289A allele was the most common. A major consideration in interpreting this survey of the literature is sampling bias; regions and environments that have been extensively sampled are more likely to show greater azole resistance even though resistance could be more prevalent in areas that are under-sampled or not sampled at all. Increased surveillance to pinpoint reservoirs, as well as antifungal stewardship, is needed to preserve this class of antifungals for crop protection and human health.

Dataset Information

Spectrophotometric detection of azole-resistant Aspergillus fumigatus with the EUCAST broth microdilution method: is it time for automated MIC reading of EUCAST antifungal susceptibility testing of Aspergillus species?

Objectives

Methods

Results

Conclusions

Publications

Spectrophotometric detection of azole-resistant Aspergillus fumigatus with the EUCAST broth microdilution method: is it time for automated MIC reading of EUCAST antifungal susceptibility testing of Aspergillus species?

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets