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Candida auris is a nosocomial pathogen responsible for an expanding global public health threat. This ascomycete yeast has been frequently isolated from hospital environments, representing a significant reservoir for transmission in healthcare settings. Here, we investigated the relationships among C. auris isolates from patients with chronic respiratory diseases admitted in a chest hospital and from their fomites, using whole-genome sequencing (WGS) and multilocus microsatellite genotyping. Overall, 37.5% (n = 12/32) patients developed colonisation by C. auris including 9.3% of the screened patients that were colonised at the time of admission and 75% remained colonised till discharge. Furthermore, 10% of fomite samples contained C. auris in rooms about 8.5 days after C. auris colonised patients were admitted. WGS and microsatellite typing revealed that multiple strains contaminated the fomites and colonised different body sites of patients. Notably, 37% of C. auris isolates were resistant to amphotericin B but with no amino acid substitution in ERG2, ERG3, ERG5, and ERG6 as compared to the reference strain B8441 in any of our strains. In addition, 55% of C. auris isolates likely had two copies of the MDR1 gene. Our results suggest significant genetic and ecological diversities of C. auris in healthcare setting. The WGS and microsatellite genotyping methods provided complementary results in genotype identification. [ABSTRACT FROM AUTHOR]

Objectives: The emergence of fluconazole resistance in Candida parapsilosis healthcare-associated infections has recently been increasingly reported. Antifungal susceptibility profiles and mechanisms of fluconazole resistance in C. parapsilosis (n = 199) from nine hospitals in India collected over a period of 3 years were studied. Further, clonal transmission of fluconazole-resistant isolates in different hospitals was investigated.Methods: Antifungal susceptibility testing of five azoles, amphotericin B and 5-flucytosine was performed by the CLSI microbroth dilution method. The azole target ERG11 gene was sequenced, and the significance of a novel ERG11 mutation in C. parapsilosis was determined using a gap-repair cloning approach in Saccharomyces cerevisiae. In addition, microsatellite analysis was performed to determine the clonal lineage of C. parapsilosis-resistant strains circulating among different hospitals.Results: A total of 64 (32%) C. parapsilosis isolates were non-susceptible to fluconazole, which included resistant (n = 55; MIC >4 mg/L) and susceptible dose-dependent (n = 9) isolates. Of these 64 non-susceptible isolates, a novel K143R amino acid substitution was noted in 92%, and the remaining five isolates had the Y132F substitution. Elevated azole MICs (≥16-fold) were detected in S. cerevisiae upon expression of C. parapsilosis ERG11 alleles carrying Y132F or K143R substitutions. Two major clusters of non-susceptible isolates were circulating in seven Indian hospitals.Conclusions: We report a novel K143R amino acid substitution in ERG11p causing fluconazole resistance in C. parapsilosis. Fluconazole-non-susceptible C. parapsilosis isolates carrying the novel K143R amino acid substitution should be identified in clinical microbiology laboratories to prevent further clonal transmission. [ABSTRACT FROM AUTHOR]

Lithium is the most common cause of nephrogenic diabetes insipidus (Li-NDI). Hydrochlorothiazide (HCTZ) combined with amiloride is the mainstay treatment in Li-NDI. The paradoxical antidiuretic action of HCTZ in Li-NDI is generally attributed to increased sodium and water uptake in proximal tubules as a compensation for increased volume loss due to HCTZ inhibition of the Na-Cl cotransporter (NCC), but alternative actions for HCTZ have been suggested. Here, we investigated whether HCTZ exerted an NCC-independent effect in Li-NDI. In polarized mouse cortical collecting duct (mpkCCD) cells, HCTZ treatment attenuated the Li-induced downregulation of aquaporin-2 (AQP2) water channel abundance. In these cells, amiloride reduces cellular Li influx through the epithelial sodium channel (ENaC). HCTZ also reduced Li influx, but to a lower extent. HCTZ increased AQP2 abundance on top of that of amiloride and did not affect the ENaC-mediated transcellular voltage. MpkCCD cells did not express NCC mRNA or protein. These data indicated that in mpkCCD cells, HCTZ attenuated lithiuminduced downregulation of AQP2 independently of NCC and ENaC. Treatment of Li-NDI NCC knockout mice with HCTZ revealed a significantly reduced urine volume, unchanged urine osmolality, and increased cortical AQP2 abundance compared with Li-treated NCC knockout mice. HCTZ treatment further resulted in reduced blood Li levels, creatinine clearance, and alkalinized urinary pH. Our in vitro and in vivo data indicate that part of the antidiuretic effect of HCTZ in Li-NDI is NCC independent and may involve a tubuloglomerular feedback response-mediated reduction in glomerular filtration rate due to proximal tubular carbonic anhydrase inhibition. [ABSTRACT FROM AUTHOR]