In vitro activity of posaconazole and comparators versus opportunistic filamentous fungal pathogens globally collected during 8 years.

The epidemiology of invasive filamentous fungal diseases requires monitoring due to changes in susceptibility patterns of new and established antifungal agents that may affect clinical practices. We evaluated the activity of posaconazole against 2,157 invasive moulds collected worldwide from 2010-2017. The isolates included 1,775 Aspergillus spp. and 382 non-Aspergillus moulds, including 81 Fusarium spp., 62 Mucorales group, and 57 Scedosporium spp. Isolates were tested using the CLSI reference broth microdilution method. Posaconazole showed similar activity to itraconazole and voriconazole against A. fumigatus. Applying published ECV, 98.0% of the A. fumigatus and 97.7% to 100.0% of other common Aspergillus species were wildtype to posaconazole. Categorical agreement between posaconazole and the other azoles tested against A. fumigatus was 98.7%. Notably, most of the Aspergillus spp. isolates recovered from this large collection were wildtype to echinocandins and all azoles. Posaconazole non-wildtype rates of A. fumigatus varied across the different geographic regions, with 2.1% in Europe, 2.2% in North America, 1.8% in Latin America, and 0.7% in the Asia-Pacific region. The frequency of azole non-wildtype A. fumigatus isolates from Europe increased steadily from 2010-2017 for all 3 triazoles (0.0%-5.0%). The azole non-wildtype A. fumigatus rates from the other geographic areas were stable over time. Fusarium and/or Scedosporium spp. isolates were highly resistant to azoles and echinocandins. Posaconazole and amphotericin B were the most active agents against the Mucorales. Posaconazole was very active against most species of Aspergillus and was comparable to itraconazole and voriconazole against the less common moulds. Posaconazole should provide a useful addition to the anti-mould grouping of antifungal agents.

Antifungal drugs work together to treat germs causing fungal infections.

Life-threatening infections can be caused by a fungus called Candida auris (shortened to C. auris) that is found in the hospital environment. This study looked at how well different drugs could treat C. auris infection. Samples were collected from 36 people who had C. auris infection. The samples were treated with single drugs and in combination. We found that the main drug types did not work on most samples. Genetic differences we found in the C. auris samples could explain why the main drugs did not work. However, a drug called isavuconazole worked on almost all samples. We also found that a drug called anidulafungin worked better against C. auris when it was combined with either isavuconazole or another drug called voriconazole. To read the full Plain Language Summary of this article, click on the View Article button above and download the PDF.

Antifungal susceptibilities of opportunistic filamentous fungal pathogens from the Asia and Western Pacific Region: data from the SENTRY Antifungal Surveillance Program (2011-2019).

Antifungal surveillance is an important tool to monitor the prevalence of uncommon fungal species and increasing antifungal resistance throughout the world, but data comparing results across several different Asian countries are scarce. In this study, 372 invasive molds collected in the Asia-Western Pacific region in 2011-2019 were susceptibility tested for mold-active triazoles (isavuconazole, posaconazole, voriconazole, and itraconazole). The collection includes 318 Aspergillus spp. isolates and 53 non-Aspergillus molds. The MIC values using CLSI methods for isavuconazole versus Aspergillus fumigatus ranged from 0.25 to 2 mg l-1. Isavuconazole, itraconazole, posaconazole, and voriconazole acted similarly against A. fumigatus. The mold-active triazoles exhibited a wildtype phenotype to most of the Aspergillus spp. isolates tested (>94%), but poor activity against Fusarium solani species complex and Lomentospora prolificans. Voriconazole was most active against the Scedosporium spp. and posaconazole was most active against the Mucorales. In summary, isavuconazole displayed excellent activity against most species of Aspergillus and was comparable to other mold-active triazoles against non-Aspergillus molds.

Evaluation of Synergistic Activity of Isavuconazole or Voriconazole plus Anidulafungin and the Occurrence and Genetic Characterization of Candida auris Detected in a Surveillance Program.

A total of 15 Candida auris isolates from the SENTRY antimicrobial surveillance program between 2006 and 2019 were combined with 21 isolates from other collections for the evaluation of antifungal susceptibility and synergy against anidulafungin plus voriconazole or isavuconazole using the checkerboard method. Surveillance isolates were analyzed for genetic relatedness and resistance mechanisms. Applying the tentative statistical epidemiological cutoff values and the Centers for Disease Control tentative breakpoints, 32/36 isolates were resistant to fluconazole, 5/36 were resistant to amphotericin B, 5/36 were non-wild-type (NWT) to anidulafungin, 3/36 were NWT to micafungin, and 1/36 and 10/36 were NWT to isavuconazole and voriconazole, respectively. Of these, 10 isolates were multidrug resistant, which means that these isolates were resistant to 2 antifungal classes. Synergy or partial synergy was noted in 5/36 and 22/36, respectively, of the isolates with the combination of anidulafungin plus voriconazole, and 11/36 and 19/36 isolates, respectively, for the combination of anidulafungin plus isavuconazole. Multilocus sequence type (MLST) analysis of the 15 SENTRY isolates demonstrated that the isolates from the US were genetically related to, but different from, isolates from Latin America (Panama and Colombia) and Germany. Single nucleotide polymorphism (SNP) analysis showed that the 15 SENTRY isolates belonged to the described international clades and had associated Erg11 alterations, including 11 isolates displaying K143R, one displaying F126L, and one displaying Y501H alterations and a fluconazole MIC result of ≥64 mg/liter. Resistance mechanisms were not observed in the two isolates displaying fluconazole MIC values at 4 and 16 mg/liter. Isavuconazole displayed activity and greater synergy when tested with anidulafungin than seen with anidulafungin plus voriconazole against the C. auris clinical isolates that displayed resistance phenotypes.

In vitro activity of isavuconazole versus opportunistic filamentous fungal pathogens from the SENTRY Antifungal Surveillance Program, 2017-2018.

The increasing prevalence of uncommon fungal species and higher antifungal resistance has turned antifungal susceptibility testing into an important monitoring tool. In response, we evaluated the activity of isavuconazole against 522 clinical mold isolates collected worldwide in 2017-2018, including 436 Aspergillus spp. isolates and 86 non-Aspergillus molds. The MIC values using Clinical and Laboratory Standards Institute methods for isavuconazole versus Aspergillus ranged from 0.015 mg/L to >8 mg/L. Isavuconazole showed comparable activity to itraconazole, posaconazole, and voriconazole against A. fumigatus species complex. Most of the Aspergillus spp. isolates tested (>90%) were wild type to all azoles and echinocandins. Eleven isolates were non-wild type to isavuconazole and the other 3 azoles, and 10 of those isolates were from Europe. The azoles and echinocandins showed poor activity against Fusarium and Scedosporium spp. Isavuconazole exhibited excellent activity against most species of Aspergillus and was comparable to itraconazole, posaconazole, and voriconazole against the less common molds.

Activity of a Long-Acting Echinocandin, Rezafungin, and Comparator Antifungal Agents Tested against Contemporary Invasive Fungal Isolates (SENTRY Program, 2016 to 2018).

We evaluated the activity of rezafungin and comparators, using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methods, against a worldwide collection of 2,205 invasive fungal isolates recovered from 2016 to 2018. Candida (n = 1,904 isolates; 6 species), Cryptococcus neoformans (n = 73), Aspergillus fumigatus (n = 183), and Aspergillus flavus (n = 45) isolates were tested for their susceptibility (S) to rezafungin as well as the comparators caspofungin, anidulafungin, micafungin, and azoles. Interpretive criteria were applied following CLSI published clinical breakpoints (CBPs) and epidemiological cutoff values (ECVs). Isolates displaying non-wild-type (non-WT) echinocandin MIC values were sequenced for hot spot (HS) mutations. Rezafungin inhibited 99.8% of Candida albicans isolates (MIC50/90, 0.03/0.06 µg/ml), 95.7% of Candida glabrata isolates (MIC50/90, 0.06/0.12 µg/ml), 97.4% of Candida tropicalis isolates (MIC50/90, 0.03/0.06 µg/ml), 100.0% of Candida krusei isolates (MIC50/90, 0.03/0.06 µg/ml), and 100.0% of Candida dubliniensis isolates (MIC50/90, 0.06/0.12 µg/ml) at ≤0.12 µg/ml. All (329/329 [100.0%]) Candida parapsilosis isolates (MIC50/90,1/2 µg/ml) were inhibited by rezafungin at ≤4 µg/ml. Fluconazole resistance was detected among 8.6% of C. glabrata isolates, 12.5% of C. parapsilosis isolates, 3.2% of C. dubliniensis isolates, and 2.6% of C. tropicalis isolates. The activity of rezafungin against these 6 Candida spp. was similar to the activity of the other echinocandins. Detection of the HS mutation was performed by sequencing echinocandin-resistant or non-WT Candida isolates. Good activity against C. neoformans was observed for fluconazole and the other azoles, whereas the echinocandins, including rezafungin, displayed limited activity. Rezafungin displayed activity similar to that of the other echinocandins against A. fumigatus and A. flavus These in vitro data contribute to accumulating research demonstrating the potential of rezafungin for preventing and treating invasive fungal infections.

Analysis of global antifungal surveillance results reveals predominance of Erg11 Y132F alteration among azole-resistant Candida parapsilosis and Candida tropicalis and country-specific isolate dissemination.

This study evaluated the activity of echinocandins, azoles and amphotericin B against Candida spp. isolates and other yeasts and characterised azole resistance mechanisms in Candida parapsilosis and Candida tropicalis. Invasive Candida spp. isolates (n = 2936) collected in 60 hospitals worldwide during 2016-2017 underwent antifungal susceptibility testing by broth microdilution. Azole-resistant C. parapsilosis and C. tropicalis were submitted to qPCR for ERG11, CDR1 and MDR1, and the whole genome sequence was analysed. Results of non-susceptibility to echinocandins ranged from 0.0-2.3%, being highest in Candida glabrata. More than 99.0% of the Candida albicans isolates were susceptible to both fluconazole and voriconazole. Fluconazole resistance in C. glabrata was 6.5% overall, being highest in the USA (13.0%). Resistance to voriconazole in Candida krusei was only noted in the USA (5.0%). Azoles inhibited 89.1-91.6% of C. parapsilosis isolates, with most resistant isolates noted in Europe (15.1%), including 36 isolates from Italy (three hospitals), of which 34 harboured Erg11 Y132F mutations and overexpressed MDR1. Azole non-wild-type C. tropicalis (7/227) were found in five countries: 3 isolates from Thailand had the same Erg11 Y132F alteration. Fluconazole non-wild-type isolates were noted among 3/77 (3.9%) Candida dubliniensis, 4/17 (23.5%) Candida guilliermondii, 4/47 (8.5%) Candida lusitaniae and other less common yeast species. Echinocandin use has been recommended over fluconazole for invasive Candida infections. However, azoles are still active against the most common Candida spp. and resistance appears to be restricted to certain geographic regions and associated with Erg11 Y132 alterations in C. parapsilosis and C. tropicalis.

CD101, a long-acting echinocandin, and comparator antifungal agents tested against a global collection of invasive fungal isolates in the SENTRY 2015 Antifungal Surveillance Program.

CD101 is a novel echinocandin with exceptional chemical stability and long-acting pharmacokinetics. The activity of CD101 and comparators was evaluated using CLSI broth microdilution methods against 713 invasive fungal isolates, including 589 Candida spp. (6 species), 14 C. neoformans, 97 A. fumigatus and 13 A. flavus species complex collected worldwide during 2015. All C. tropicalis, C. krusei and C. dubliniensis, 99.7% of C. albicans and 98.3% of C. glabrata were inhibited by ≤0.12 µg/mL of CD101, and these isolates were susceptible/wild type to other echinocandins using CLSI clinical breakpoint and epidemiological cutoff value (ECV) interpretive criteria. C. parapsilosis displayed higher MIC values (range 0.25-2 µg/mL), but similar results were observed for other echinocandins. One C. glabrata and one C. albicans with CD101 MIC value at 1 and 0.25 µg/mL possessed F625S and S645P alterations on FKS1, respectively. These isolates also displayed elevated MIC values for at least one clinically available echinocandin. Fluconazole resistance was noted for 6.6% of C. glabrata and 3.6% C. parapsilosis. Echinocandins had limited activity against C. neoformans. CD101 activity against A. fumigatus and A. flavus (MEC ≤0.03 µg/mL) was comparable to other echinocandins (MEC ≤0.03 µg/mL). These moulds had MIC values below ECVs for the mould-active azoles. CD101 was as active as other echinocandins against common fungal organisms recovered from invasive fungal infections. The extended half-life profile is very desirable as less frequent dosing of this agent should facilitate shorter and more cost-effective hospital stays, improve compliance for outpatients, and provide more convenient outpatient prophylaxis.

Differential Activity of the Oral Glucan Synthase Inhibitor SCY-078 against Wild-Type and Echinocandin-Resistant Strains of Candida Species.

SCY-078 (formerly MK-3118) is a novel orally active inhibitor of fungal ß-(1,3)-glucan synthase (GS). SCY-078 is a derivative of enfumafungin and is structurally distinct from the echinocandin class of antifungal agents. We evaluated the in vitro activity of this compound against wild-type (WT) and echinocandin-resistant isolates containing mutations in the FKS genes of Candida spp. Against 36 Candida spp. FKS mutants tested, 30 (83.3%) were non-WT to 1 or more echinocandins, and only 9 (25.0%) were non-WT (MIC, >WT-upper limit) to SCY-078. Among C. glabrata isolates carrying FKS alterations, 84.0% were non-WT to the echinocandins versus only 24.0% for SCY-078. In contrast to the echinocandin comparators, the activity of SCY-078 was minimally affected by the presence of FKS mutations, suggesting that this agent is useful in the treatment of Candida infections due to echinocandin-resistant strains.

Activity of a Long-Acting Echinocandin (CD101) and Seven Comparator Antifungal Agents Tested against a Global Collection of Contemporary Invasive Fungal Isolates in the SENTRY 2014 Antifungal Surveillance Program.

The activity of CD101 and comparator antifungal agents against 606 invasive fungal isolates collected worldwide during 2014 was evaluated using the Clinical and Laboratory Standards Institute (CLSI) method. All Candida albicans (n = 251), Candida tropicalis (n = 51), Candida krusei (n = 16), and Candida dubliniensis (n = 11) isolates were inhibited by ≤0.12 µg/ml of CD101 and were susceptible or showed wild-type susceptibility to the other echinocandins tested. Five C. glabrata isolates (n = 100) displayed CD101 MIC values of 1 to 4 µg/ml, had elevated MICs of caspofungin (2 to >8 µg/ml), anidulafungin (2 to 4 µg/ml), and micafungin (2 to 4 µg/ml), and carried mutations on fks1 and fks2Candida parapsilosis (n = 92) and Candida orthopsilosis (n = 10) displayed higher CD101 MIC values (ranges, 0.5 to 4 µg/ml and 0.12 to 2 µg/ml, respectively), and similar results were observed for the other echinocandins tested. Fluconazole resistance was noted among 11.0% of Candida glabrata isolates, 4.3% of C. parapsilosis isolates, and 2.0% of C. albicans and C. tropicalis isolates. The activity of CD101 against Aspergillus fumigatus (n = 56) was similar to that of micafungin and 2-fold greater than that of caspofungin but less than that of anidulafungin. These isolates had wild-type susceptibility to itraconazole, voriconazole, and posaconazole. The echinocandins had limited activity against Cryptococcus neoformans (n = 19). CD101 was as active as the other echinocandins against common fungal organisms recovered from patients with invasive fungal infections. The long half-life profile is very desirable for the prevention and treatment of serious fungal infections, especially in patients who can then be discharged from the hospital to complete antifungal therapy on an outpatient basis.

Activity of a long-acting echinocandin, CD101, determined using CLSI and EUCAST reference methods, against Candida and Aspergillus spp., including echinocandin- and azole-resistant isolates.

OBJECTIVES: The objective of this study was to evaluate the in vitro activity of CD101, a novel echinocandin with a long serum elimination half-life, and comparator (anidulafungin and caspofungin) antifungal agents against a collection of Candida and Aspergillus spp. isolates. METHODS: CD101 and comparator agents were tested against 106 Candida spp. and 67 Aspergillus spp. isolates, including 27 isolates of Candida harbouring fks hotspot mutations and 12 itraconazole non-WT Aspergillus, using CLSI and EUCAST reference susceptibility broth microdilution (BMD) methods. RESULTS: Against WT and fks mutant Candida albicans, Candida glabrata and Candida tropicalis, the activity of CD101 [MIC90 = 0.06, 0.12 and 0.03 mg/L, respectively (CLSI method values)] was comparable to that of anidulafungin (MIC90 = 0.03, 0.12 and 0.03 mg/L, respectively) and caspofungin (MIC90 = 0.12, 0.25 and 0.12 mg/L, respectively). WT Candida krusei isolates were very susceptible to CD101 (MIC = 0.06 mg/L). CD101 activity (MIC50/90 = 1/2 mg/L) was comparable to that of anidulafungin (MIC50/90 = 2/2 mg/L) against Candida parapsilosis. CD101 (MIC mode = 0.06 mg/L for C. glabrata) was 2- to 4-fold more active against fks hotspot mutants than caspofungin (MIC mode = 0.5 mg/L). CD101 was active against Aspergillus fumigatus, Aspergillus terreus, Aspergillus niger and Aspergillus flavus (MEC90 range = ≤0.008-0.03 mg/L). The essential agreement between CLSI and EUCAST methods for CD101 was 92.0%-100.0% among Candida spp. and 95.0%-100.0% among Aspergillus spp. CONCLUSIONS: The activity of CD101 is comparable to that of other members of the echinocandin class for the prevention and treatment of serious fungal infections. Similar results for CD101 activity versus Candida and Aspergillus spp. may be obtained with either CLSI or EUCAST BMD methods.

Antifungal susceptibility patterns of a global collection of fungal isolates: results of the SENTRY Antifungal Surveillance Program (2013).

Among 1846 fungal clinical isolates from 31 countries, echinocandin resistance in Candida spp. ranged from 0.0% to 2.8% (highest for anidulafungin versus Candida glabrata), and fluconazole resistance was noted among 11.9% and 11.6% of the C. glabrata and Candida tropicalis, respectively. Two isolates of Aspergillus fumigatus displayed elevated MICs for itraconazole and carried cyp51a mutations encoding TR34 L98H. All Cryptococcus neoformans had azole MIC values below epidemiological cutoff values. The increasing resistance among certain species and more frequent reports of breakthrough infections in patients undergoing antifungal therapy highlights the importance of antifungal surveillance to guide therapy for patients with invasive fungal infections.

Antifungal susceptibilities of Candida, Cryptococcus neoformans and Aspergillus fumigatus from the Asia and Western Pacific region: data from the SENTRY antifungal surveillance program (2010-2012).

The SENTRY Antifungal Surveillance Program monitors global susceptibility rates of newer and established antifungal agents. We report the in vitro activity of seven antifungal agents against 496 contemporary clinical isolates of yeasts and molds. The isolates were obtained from 20 laboratories in the Asia-Western Pacific (APAC) region during 2010 through 2012. Anidulafungin, caspofungin, micafungin, fluconazole, itraconazole, posaconazole and voriconazole were susceptibility tested using CLSI methods and species-specific interpretive criteria. Sequencing of fks hot spots was performed for echinocandin-resistant strains. Isolates included 13 species of Candida (n=460), 5 species of non-Candida yeasts (21), 5 species of Aspergillus (11) and 4 other molds. Echinocandin resistance was uncommon among eight species of Candida and was only detected in three isolates of Candida glabrata, two from Australia harboring mutations in fks1 (F625S) and fks2 (S663P). Resistance to the azoles was much more common and was observed among all species with the exception of Candida dubliniensis. Fluconazole resistance rates observed with C. glabrata (6.8%) was comparable to that seen with Candida parapsilosis (5.7%) and Candida tropicalis (3.6%). Cross resistance among the triazoles was seen with each of these three species. The mold-active azoles and the echinocandins were all active against isolates of Aspergillus fumigatus. Azole resistance was not detected among the isolates of Cryptococcus neoformans. Antifungal resistance is uncommon among isolates of fungi causing invasive fungal infections in the APAC region. As in other regions of the world, emerging resistance to the echinocandins among invasive isolates of C. glabrata bears close monitoring.

In vitro antifungal susceptibilities of isolates of Candida spp. and Aspergillus spp. from China to nine systemically active antifungal agents: data from the SENTRY antifungal surveillance program, 2010 through 2012.

We report the in vitro activity of nine systemically active antifungal agents against 237 contemporary clinical isolates of yeast and moulds obtained from 13 laboratories in China during 2010 through 2012. Susceptibility testing was performed using CLSI methods. Sequencing of fks hot spots was performed for echinocandin non-wild-type (WT) strains. Isolates included 220 from eight species of Candida, 15 from four species of Aspergillus and one isolate each of Rhodotorula mucilaginosa and Trichosporon asahii. Resistance to amphotericin B (0.0%), flucytosine (0.0-1.7%) and the echinocandins (0.0-3.4%) was distinctly uncommon among C. albicans, C. parapsilosis, C. tropicalis, C. glabrata and C. pelliculosa. Three C. albicans isolates showed resistance to echinocandins and one harboured a mutation in HS1 of fks1. Resistance to the azoles was much more common with resistance to fluconazole, voriconazole and posaconazole detected among isolates of C. glabrata and C. tropicalis. Both C. parapsilosis and C. pelliculosa exhibited decreased susceptibility to fluconazole. Amphotericin B, the mould-active azoles and the echinocandins were all quite active against isolates of A. fumigatus and A. flavus. Consistent with previous studies from China, resistance to fluconazole is prominent among Candida spp. isolates in this country.

Activity of echinocandins and triazoles against a contemporary (2012) worldwide collection of yeast and moulds collected from invasive infections.

In this study, 1717 fungal clinical isolates causing invasive fungal infections were evaluated against nine antifungal agents using Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution methods. The isolates comprised 1487 Candida spp., 109 Aspergillus spp., 86 non-Candida yeasts (including 52 isolates of Cryptococcus neoformans) and 35 rare moulds obtained during 2012 from 72 hospitals worldwide. Echinocandin resistance among Candida spp. was low, and resistance rates to anidulafungin, caspofungin and micafungin varied from 0.0% to 2.8% among different species. Echinocandin-resistant Candida glabrata were shown to have fks mutations (fks2 HS1 F659Y, F659del, S663F and S663P), and fluconazole resistance was also observed in those strains. One Candida krusei and one Candida dubliniensis had L701M or S645P fks1 mutations, respectively. Candida tropicalis and C. glabrata had higher fluconazole resistance rates of 6.1% and 6.9%, respectively, compared with other Candida spp. Fluconazole-resistant C. tropicalis were collected in five countries (USA, China, Germany, Belgium and Thailand). Voriconazole was active against all Candida spp., inhibiting 91.2-99.7% of isolates using species-specific breakpoints. All agents except for the echinocandins and posaconazole were active against Cr. neoformans. Triazoles were active against other yeasts [MIC90 (minimum inhibitory concentration encompassing 90% of isolates tested), 2µg/mL]. The echinocandins and the mould-active triazoles were active against Aspergillus [MIC/MEC90 (minimum effective concentration encompassing 90% of isolates tested) range, 0.015-2µg/mL], but the activity of these agents was limited against uncommon mould species (MIC/MEC90 range, 4µg/mL to >16µg/mL).

Isavuconazole and nine comparator antifungal susceptibility profiles for common and uncommon Candida species collected in 2012: application of new CLSI clinical breakpoints and epidemiological cutoff values.

The in vitro activity of isavuconazole and nine antifungal comparator agents was assessed using reference broth microdilution methods against 1,421 common and uncommon species of Candida from a 2012 global survey. Isolates were identified using CHROMagar, biochemical methods and sequencing of ITS and/or 28S regions. Candida spp. were classified as either susceptible or resistant and as wild type (WT) or non-WT using CLSI clinical breakpoints or epidemiological cutoff values, respectively, for the antifungal agents. Isolates included 1,421 organisms from 21 different species of Candida. Among Candida spp., resistance to all 10 tested antifungal agents was low (0.0-7.9 %). The vast majority of each species of Candida, with the exception of Candida glabrata, Candida krusei, and Candida guilliermondii (modal MICs of 0.5 µg/ml), were inhibited by ≤0.12 µg/ml of isavuconazole (99.0 %; range 94.3 % [Candida tropicalis] to 100.0 % [Candida lusitaniae and Candida dubliniensis]). C. glabrata, C. krusei, and C. guilliermondii were largely inhibited by ≤1 µg/ml of isavuconazole (89.7, 96.9 and 92.8 %, respectively). Decreased susceptibility to isavuconazole was most prominent with C. glabrata where the modal MIC for isavuconazole was 0.5 µg/ml for those strains that were SDD to fluconazole or WT to voriconazole, and was 4 µg/ml for those that were either resistant or non-WT to fluconazole or voriconazole, respectively. In conclusion, these data document the activity of isavuconazole and generally the low resistance levels to the available antifungal agents in a large, contemporary (2012), global collection of molecularly characterized species of Candida.

Comparison of EUCAST and CLSI broth microdilution methods for the susceptibility testing of 10 systemically active antifungal agents when tested against Candida spp.

The antifungal broth microdilution (BMD) method of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) was compared with Clinical and Laboratory Standards Institute (CLSI) BMD method M27-A3 for amphotericin B, flucytosine, anidulafungin, caspofungin, micafungin, fluconazole, isavuconazole, itraconazole, posaconazole, and voriconazole susceptibility testing of 357 isolates of Candida. The isolates were selected from global surveillance collections to represent both wild-type (WT) and non-WT MIC results for the azoles (12% of fluconazole and voriconazole results were non-WT) and the echinocandins (6% of anidulafungin and micafungin results were non-WT). The study collection included 114 isolates of Candida albicans, 73 of C. glabrata, 76 of C. parapsilosis, 60 of C. tropicalis, and 34 of C. krusei. The overall essential agreement (EA) between EUCAST and CLSI results ranged from 78.9% (posaconazole) to 99.6% (flucytosine). The categorical agreement (CA) between methods and species of Candida was assessed using previously determined CLSI epidemiological cutoff values. The overall CA between methods was 95.0% with 2.5% very major (VM) and major (M) discrepancies. The CA was >93% for all antifungal agents with the exception of caspofungin (84.6%), where 10% of the results were categorized as non-WT by the EUCAST method and WT by the CLSI method. Problem areas with low EA or CA include testing of amphotericin B, anidulafungin, and isavuconazole against C. glabrata, itraconazole, and posaconazole against most species, and caspofungin against C. parapsilosis, C. tropicalis, and C. krusei. We confirm high level EA and CA (>90%) between the 2 methods for testing fluconazole, voriconazole, and micafungin against all 5 species. The results indicate that the EUCAST and CLSI methods produce comparable results for testing the systemically active antifungal agents against the 5 most common species of Candida; however, there are several areas where additional steps toward harmonization are warranted.

Frequency of fks mutations among Candida glabrata isolates from a 10-year global collection of bloodstream infection isolates.

Among 119 echinocandin non-wild-type (non-WT) Candida glabrata strains from two global surveys, mutations in fks hot spots (HSs) were detected in 28 (from 7 countries and 8 U.S. states): 24 strains (85.7%) had non-WT MICs for micafungin, 22 (78.6%) for anidulafungin, and 25 (89.3%) for caspofungin. The most common FKS substitutions among non-WT strains were at positions F659 (n = 7) and S663 (n = 7). Three isolates displaying WT MIC results had F625Y, L630I, and D632Y substitutions or non-HS mutations. Mutations that have been reported to decrease the echinocandin binding to the 1,3-ß-d-glucan synthase were categorized as resistant by applying the new CLSI breakpoint criteria for all three echinocandins.

Use of micafungin as a surrogate marker to predict susceptibility and resistance to caspofungin among 3,764 clinical isolates of Candida by use of CLSI methods and interpretive criteria.

Due to unacceptably high interlaboratory variation in caspofungin MIC values, we evaluated the use of micafungin as a surrogate marker to predict the susceptibility of Candida spp. to caspofungin using reference methods and species-specific interpretive criteria. The MIC results for 3,764 strains of Candida (eight species), including 73 strains with fks mutations, were used. Caspofungin MIC values and species-specific interpretive criteria were compared with those of micafungin to determine the percent categorical agreement (%CA) and very major error (VME), major error (ME), and minor error rates as well as their ability to detect fks mutant strains of Candida albicans (11 mutants), Candida tropicalis (4 mutants), Candida krusei (3 mutants), and Candida glabrata (55 mutants). Overall, the %CA was 98.8% (0.2% VMEs and MEs, 0.8% minor errors) using micafungin as the surrogate marker. Among the 60 isolates of C. albicans (9 isolates), C. tropicalis (5 isolates), C. krusei (2 isolates), and C. glabrata (44 isolates) that were nonsusceptible (either intermediate or resistant) to both caspofungin and micafungin, 54 (90.0%) contained a mutation in fks1 or fks2. An additional 10 C. glabrata mutants, two C. albicans mutants, and one mutant each of C. tropicalis and C. krusei were classified as susceptible to both antifungal agents. Using the epidemiological cutoff values (ECVs) of 0.12 µg/ml for caspofungin and 0.03 µg/ml for micafungin to differentiate wild-type (WT) from non-WT strains of C. glabrata, 80% of the C. glabrata mutants were non-WT for both agents (96% concordance). Micafungin may serve as an acceptable surrogate marker for the prediction of susceptibility and resistance of Candida to caspofungin.