Tandem gene duplications contributed to high-level azole resistance in a rapidly expanding Candida tropicalis population.

Invasive diseases caused by the globally distributed commensal yeast Candida tropicalis are associated with mortality rates of greater than 50%. Notable increases of azole resistance have been observed in this species, particularly within Asia-Pacific regions. Here, we carried out a genetic population study on 1571 global C. tropicalis isolates using multilocus sequence typing (MLST). In addition, whole-genome sequencing (WGS) analysis was conducted on 629 of these strains, comprising 448 clinical invasive strains obtained in this study and 181 genomes sourced from public databases. We found that MLST clade 4 is the predominant azole-resistant clone. WGS analyses demonstrated that dramatically increasing rates of azole resistance are associated with a rapid expansion of cluster AZR, a sublineage of clade 4. Cluster AZR isolates exhibited a distinct high-level azole resistance, which was induced by tandem duplications of the ERG11A395T gene allele. Ty3/gypsy-like retrotransposons were found to be highly enriched in this population. The alarming expansion of C. tropicalis cluster AZR population underscores the urgent need for strategies against growing threats of antifungal resistance.

Emergence of Antifungal Resistant Subclades in the Global Predominant Phylogenetic Population of Candida albicans.

Candida albicans remains the most common species causing invasive candidiasis. In this study, we present the population structure of 551 global C. albicans strains. Of these, the antifungal susceptibilities of 370 strains were tested. Specifically, 66.6% of the azole-nonsusceptible (NS)/non-wild-type (NWT) strains that were tested belonged to Clade 1. A phylogenetic analysis, a principal components analysis, the population structure, and a loss of heterozygosity events revealed two nested subclades in Clade 1, namely, Clade 1-R and Clade 1-R-α, that exhibited higher azole-NS/NWT rates (75.0% and 100%, respectively). In contrast, 6.4% (21/326) of the non-Clade 1-R isolates were NS/NWT to at least 1 of 4 azoles. Notably, all of the Clade 1-R-α isolates were pan-azole-NS/NWT that carried unique A114S and Y257H double substitutions in Erg11p and had the overexpression of ABC-type efflux pumps introduced by the substitution A736V in transcript factor Tac1p. It is worth noting that the Clade 1-R and Clade 1-R-α isolates were from different cities that are distributed over a large geographic span. Our study demonstrated the presence of specific phylogenetic subclades that are associated with antifungal resistance among C. albicans Clade 1, which calls for public attention on the monitoring of the future spread of these clones. IMPORTANCE Invasive candidiasis is the most common human fungal disease among hospitalized patients, and Candida albicans is the predominant pathogen. Considering the large number of infected cases and the limited alternative therapies, the azole-resistance of C. albicans brings a huge clinical threat. Here, our study suggested that antifungal resistance in C. albicans could also be associated with phylogenetic lineages. Specifically, it was revealed that more than half of the azole-resistant C. albicans strains belonged to the same clade. Furthermore, two nested subclades of the clade exhibited extremely high azole-resistance. It is worth noting that the isolates of two subclades were from different cities that are distributed over a large geographic span in China. This indicates that the azole-resistant C. albicans subclades may develop into serious public health concerns.

Study of an antifungal medicine isavuconazole used in treatment of mold infections in China: A plain language summary.

WHAT IS THIS SUMMARY ABOUT?: Molds are types of fungus that can cause sickness and death. Mold infections are increasing in China. Until 2022, medicines that can effectively treat all mold infections were still lacking in China. This summary of a study originally published in the journal Infection and Drug Resistance. The study took place in China and tested a medicine called isavuconazole on mold samples to check if isavuconazole can be used to treat mold infections. Isavuconazole became available in China in January 2022 as a capsule (a hard gel-covered pill filled with a dose of medicine) and in June 2022 as an injection or a shot. WHAT WERE THE RESULTS?: Isavuconazole stopped the growth of most molds. Other medicines were needed at higher amounts to stop the growth of molds. WHAT DO THE RESULTS OF THE STUDY MEAN?: Isavuconazole is another option to treat mold infections in China.

In vitro Activity of Isavuconazole and Comparators Against Clinical Isolates of Molds from a Multicenter Study in China.

Purpose: Monitoring antifungal susceptibility patterns for new or established antifungals is imperative. Antifungal resistance is frequent in molds, frequently leading to invasive mold infections (IMIs) in immunocompromised patients with high morbidity and mortality. Limited availability of effective antifungals for treatment of IMIs in China is an enormous challenge. The purpose of this study was to monitor in vitro antifungal resistance profiles of mold isolates from China, with a particular focus on evaluating in vitro isavuconazole (ISA) activity against these isolates, contributing to the treatment guidance in clinics. Methods: We evaluated the in vitro activity of ISA and its comparators (voriconazole [VOR] and amphotericin B [AMB]) against 131 clinical isolates of Aspergillus spp. (n = 105) and Mucorales order (n = 26) collected between 2017 and 2020 from China. Results: ISA and VOR exhibited similar in vitro activity against Aspergillus spp., with minimum inhibitory concentration (MIC)50 of 1 µg/mL and MIC90 of 2 µg/mL, respectively. Overall, AMB was less active than azoles against Aspergillus spp. (MIC50: 4 µg/mL, MIC90: 8 µg/mL). Against the Mucorales order, ISA demonstrated MIC50 of 0.5 µg/mL and MIC90 of 1 µg/mL; however, one strain each of Mucor circinelloides and Syncephalastrum racemosum were resistant to ISA (MICs: >8 µg/mL). VOR exhibited little or no activity (MIC50: 8 µg/mL, MIC90: >8 µg/mL) against the Mucorales order, whereas AMB had MIC50 and MIC90 of 1 µg/mL. Conclusion: This was the first multicenter, in vitro study conducted in China and demonstrated the excellent activities of ISA against most species of the Mucorales order. MIC indicated an advantage over currently available azole antifungals, positioning ISA as a potential alternative to VOR for clinical management of IMIs. As with other antimicrobials, clinicians should employ stewardship and best practices in relation to potential resistance to new azole antifungals.

Antifungal Susceptibility Profiles and Resistance Mechanisms of Clinical Diutina catenulata Isolates With High MIC Values.

Diutina catenulata (Candida catenulata) is an ascomycete yeast species widely used in environmental and industrial research and capable of causing infections in humans and animals. At present, there are only a few studies on D. catenulata, and further research is required for its more in-depth characterization and analysis. Eleven strains of D. catenulata collected from China Hospital Invasive Fungal Surveillance Net (CHIF-NET) and the CHIF-NET North China Program were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry and internal transcribed spacer sequencing. The antifungal susceptibility of the Diutina catenulata strains was tested using the Clinical and Laboratory Standards Institute broth microdilution method and Sensititre YeastOne™. Furthermore, ERG11 and FKS1 were sequenced to determine any mutations related to azole and echinocandin resistance in D. catenulata. All isolates exhibited low minimum inhibitory concentration (MIC) values for itraconazole (0.06-0.12 µg/ml), posaconazole (0.06-0.12 µg/ml), amphotericin B (0.25-1 µg/ml), and 5-flucytosine (range, <0.06-0.12 µg/ml), whereas four isolates showed high MICs (≥4 µg/ml) for echinocandins. Strains with high MIC values for azoles showed common ERG11 mutations, namely, F126L/K143R. In addition, L139R mutations may be linked to high MICs of fluconazole. Two amino acid alterations reported to correspond to high MIC values of echinocandin, namely, F621I (F641) and S625L (S645), were found in the hot spot 1 region of FKS1. In addition, one new amino acid alteration, I1348S (I1368), was found outside of the FKS1 hot spot 2 region, and its contribution to echinocandin resistance requires future investigation. Diutina catenulata mainly infects patients with a weak immune system, and the high MIC values for various antifungals exhibited by these isolates may represent a challenge to clinical treatment.

Developing Two Rapid Protein Extraction Methods Using Focused-Ultrasonication and Zirconia-Silica Beads for Filamentous Fungi Identification by MALDI-TOF MS.

Filamentous fungi identification by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been challenging due to the lack of simple and rapid protein extraction methods and insufficient species coverage in the database. In this study, we created two rapid protein extraction methods for filamentous fungi: a one-step zirconia-silica beads method (ZSB) and a focused-ultrasonication method (FUS). The identification accuracy of two methods were evaluated with the VITEK MS, as well as number of spectra peaks and signal-to-noise ratio (S/N) with M-Discover 100 MALDI-TOF MS compared to the routine method. The better method was applied to build a filamentous fungi in-house spectra library for the M-Discover 100 MS, and then another one and routine method were performed in parallel to verify the accuracy and commonality of the in-house library. Using the two optimized methods, the dedicated operating time before MALDI-TOF MS analysis was reduced from 30 min to 7 (ZSB) or 5 (FUS) min per sample, with only a few seconds added for each additional strain. And both two methods identified isolates from most mold types equal to or better than the routine method, and the total correct identification rate using VITEK MS was 79.67, 76.42, and 76.42%, respectively. On the other hand, the two rapid methods generally achieved higher maximum and minimum S/N ratios with these isolates tested as compared to the routine method. Besides, the ZSB method produced overall mean of maximum and minimum S/N ratio higher than that by FUS. An in-house library of M-Discover MS was successfully built from 135 isolates from 42 species belonging to 18 genera using the ZSB method. Analysis of 467 isolates resulted in 97.22% correctly identified isolates to the species level by the ZSB method versus 95.50% by the routine method. The two novel methods are time- and cost-effective and allow efficient identification of filamentous fungi while providing a simplified procedure to build an in-house library. Thus, more clinical laboratories may consider adopting MALDI-TOF MS for filamentous fungi identification in the future.

Five-Year National Surveillance of Invasive Candidiasis: Species Distribution and Azole Susceptibility from the China Hospital Invasive Fungal Surveillance Net (CHIF-NET) Study.

Data on the epidemiology of invasive candidiasis (IC) and the antifungal susceptibility of Candida isolates in China are still limited. Here we report on surveillance for IC from the China Hospital Invasive Fungal Surveillance Net (CHIF-NET) study. Sixty-five tertiary hospitals collected 8,829 Candida isolates from 1 August 2009 to 31 July 2014. Matrix-assisted laser desorption ionization-time of flight mass spectrometry supplemented by ribosomal DNA sequencing was used to define the species, and the fluconazole and voriconazole susceptibilities were determined by the Clinical and Laboratory Standards Institute disk diffusion method. A total of 32 Candida species were identified. Candida albicans was the most common species (44.9%), followed by the C. parapsilosis complex (20.0%), C. tropicalis (17.2%), and the C. glabrata complex (10.8%), with other species comprising <3% of isolates. However, in candidemia, the proportion of cases caused by C. albicans was only 32.3%. C. albicans and C. parapsilosis complex isolates were susceptible to fluconazole and voriconazole (<6% resistance), while fluconazole and azole cross-resistance rates were high in C. tropicalis (13.3% and 12.9%, respectively), C. glabrata complex (18.7% and 14%, respectively), and uncommon Candida species (44.1% and 10.3%, respectively) isolates. Moreover, from years 1 to 5 of the study, there was a significant increase in the rates of resistance to fluconazole among C. glabrata complex isolates (12.2% to 24.0%) and to both fluconazole (5.7% to 21.0%) and voriconazole (5.7% to 21.4%) among C. tropicalis isolates (P < 0.01 for all comparisons). Geographic variations in the causative species and susceptibilities were noted. Our findings indicate that antifungal resistance has become noteworthy in China, and enhanced surveillance is warranted.

Sublethal vancomycin-induced ROS mediating antibiotic resistance in Staphylococcus aureus.

Staphylococcus aureus is the leading cause of many human infectious diseases. Besides infectious dangers, S. aureus is well-known for the quickly developed drug resistance. Although great efforts have been made, mechanisms underlying the antibiotic effects of S. aureus are still not well clarified. Recently, reports have shown that oxidative stress connects with bactericidal antibiotics [Dwyer et al. (2009) Curr. Opin. Microbiol. 12: , 482-489]. Based on this point, we demonstrate that reactive oxygen species (ROS) induced by sublethal vancomycin may be partly responsible for the antibiotic resistance in heterogeneous vancomycin resistant S. aureus (hVRSA). Sublethal vancomycin treatment may induce protective ROS productions in hVRSA, whereas reduction in ROS level in hVRSA strains may increase their vancomycin susceptibility. Moreover, low dose of ROS in VSSA (vancomycin susceptible S. aureus) strains may promote their survival under vancomycin conditions. Our findings reveal that modest ROS generation may be protective for vancomycin resistance in hVRSA. These results recover novel insights into the relationship between oxidative stress and bacterial resistance, which has important applications for further use of antibiotics and development of therapeutics strategies for hVRSA.

Peripheral T cells derived from Alzheimer's disease patients overexpress CXCR2 contributing to its transendothelial migration, which is microglial TNF-alpha-dependent.

The mechanism of circulating T cells entry into the brain in Alzheimer's diseases (AD) remains unclear. Here, we showed that peripheral T cells derived from AD patients overexpress CXCR2 to enhance its transendothelial migration. T cells migration through in vitro blood-brain barrier model was effectively blocked by anti-CXCR2 antibody or IL-8 (a CXCR2 ligand) RNAi in human brain microvascular endothelial cells (HBMECs). Amyloid beta (Abeta) injection in rat hippocampus upregulated CXCR2 expression accompanied with increased T cells occurrence in the brain, and this enhanced T cells entry was effectively blocked by CXCR2 antagonist. Furthermore, anti-TNF-alpha antibody blocked IL-8 production in HBMECs and T cells transendothelial migration caused by the culture supernatant of microglia treated with Abeta. Blockage of intracerebral TNF-alpha abolished the upregulation of CXCR2 in peripheral T cells and the increased T cells occurrence in the brain induced by Abeta injection in rat hippocampus. These data suggest that CXCR2 overexpression in peripheral T cells is intracerebral microglial TNF-alpha-dependent and TNF-alpha primes T cells transendothelial migration in Alzheimer's diseases.

Peripheral T cells overexpress MIP-1alpha to enhance its transendothelial migration in Alzheimer's disease.

It is unclear how circulating T cells cross the blood-brain barrier (BBB) and participate in the inflammation process in Alzheimer's disease (AD). Here we showed significantly higher macrophage inflammatory protein-1alpha (MIP-1alpha) expression in peripheral T lymphocytes of AD patients than age-matched controls. T cells crossing of the human brain microvascular endothelial cells (HBMECs) which constitute the BBB, were almost completely abrogated by anti-MIP-1alpha antibody. MIP-1alpha induced the expression of CCR5, a potential MIP-1alpha receptor, on HBMECs. HBMECs tranfected with CCR5 resulted in increased T cells transendothelial migration. CCR5 antagonist (2D7 mAb) blocked the T cells transmigration. The MIP-1alpha-CCR5 interaction promoted T cells transendothelial migration via ROCK (Rho kinase). Furthermore, Abeta injection into rats' hippocampus induced MIP-1alpha overexpression accompanied with increased T lymphocytes occurrence in the brain cortex and this enhanced T cells entry was effectively blocked by anti-MIP-1alpha antibody. These data are the first to suggest that the interaction between MIP-1alpha overexpressed by T cells and CCR5 on HBMECs is involved in AD patients' T cells migrating from blood to brain.