Epidemiological trends show a dramatic increase in the prevalence of fungal infections, and in the isolation of multidrug-resistant species, such as Candida auris. CHROMagarTM Candida (CC; CHROMagar, ...Paris, France) and other chromogenic media, which are widely used in the clinical laboratory because they allow a rapid identification of most Candida species. Recently, CHROMagarTM Candida Plus (CC-Plus; CHROMagar, Paris, France) was developed to detect and differentiate C. auris in addition to other major clinical Candida species, such as C. albicans, C. tropicalis, C. glabrata, or C. krusei. C. auris colonies display a differential light blue color with a blue halo. A multicentric study was designed to evaluate the performance of the CC-Plus medium in the detection of Candida species in patients’ surveillance and environmental samples from three Spanish hospitals with active C. auris outbreaks. A total of 364 patients’ surveillance samples and 212 environmental samples were tested. Samples were inoculated in CC and CC-Plus in parallel, and the plates were read at 24 and 48 h. All recovered colonies were presumptively identified according to colony color described by manufacturer, and the definitive identification was performed by mass spectrometry at 48 h. A total of 134 C. auris isolates were obtained (101 from patients’ surveillance samples, and 33 from environmental samples). Sensitivity, specificity, and predictive positive and negative values were 99.5%, 100%, 100%, and 99.1%, respectively, for the main clinical Candida species, showing that CC-Plus is comparable to CC, with the advantage of being able to differentiate C. auris from C. parapsilosis. Furthermore, CC-Plus was able to detect one C. albicans, one C. glabrata, and eight C. auris that did not grow in CC. Additionally, the yeast colonies were generally larger, suggesting that this novel medium could be a richer medium, and suitable for surveillance and environmental cultures of C. auris and other clinically relevant Candida species.
Epidemiological trends show a dramatic increase in the prevalence of fungal infections, and in the isolation of multidrug-resistant species, such as
CHROMagar
Candida (CC; CHROMagar, Paris, France) ...and other chromogenic media, which are widely used in the clinical laboratory because they allow a rapid identification of most
species. Recently, CHROMagar
Candida Plus (CC-Plus; CHROMagar, Paris, France) was developed to detect and differentiate
in addition to other major clinical
species, such as
,
.
,
, or
display a differential light blue color with a blue halo. A multicentric study was designed to evaluate the performance of the CC-Plus medium in the detection of
species in patients' surveillance and environmental samples from three Spanish hospitals with active
outbreaks. A total of 364 patients' surveillance samples and 212 environmental samples were tested. Samples were inoculated in CC and CC-Plus in parallel, and the plates were read at 24 and 48 h. All recovered colonies were presumptively identified according to colony color described by manufacturer, and the definitive identification was performed by mass spectrometry at 48 h. A total of 134
isolates were obtained (101 from patients' surveillance samples, and 33 from environmental samples). Sensitivity, specificity, and predictive positive and negative values were 99.5%, 100%, 100%, and 99.1%, respectively, for the main clinical
species, showing that CC-Plus is comparable to CC, with the advantage of being able to differentiate
from
. Furthermore, CC-Plus was able to detect one
, one
, and eight
that did not grow in CC. Additionally, the yeast colonies were generally larger, suggesting that this novel medium could be a richer medium, and suitable for surveillance and environmental cultures of
and other clinically relevant
species.
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.
