Candida auris is an emerging yeast that causes healthcare-associated infections. It can be misidentified by laboratories and often is resistant to antifungal medications. We describe an outbreak of C. auris infections in healthcare facilities in New York City, New York, USA. The investigation included laboratory surveillance, record reviews, site visits, contact tracing with cultures, and environmental sampling. We identified 51 clinical case-patients and 61 screening case-patients. Epidemiologic links indicated a large, interconnected web of affected healthcare facilities throughout New York City. Of the 51 clinical case-patients, 23 (45%) died within 90 days and isolates were resistant to fluconazole for 50 (98%). Of screening cultures performed for 572 persons (1,136 total cultures), results were C. auris positive for 61 (11%) persons. Environmental cultures were positive for samples from 15 of 20 facilities. Colonization was frequently identified during contact investigations; environmental contamination was also common.

Candida auris is an emerging multidrug-resistant yeast causing invasive health care-associated infection with high mortality worldwide. Rapid identification of C. auris is of primary importance for the implementation of public health measures to control the spread of infection. To achieve these goals, we developed and validated a TaqMan-based real-time PCR assay targeting the internal transcribed spacer 2 (ITS2) region of the ribosomal gene. The assay was highly specific, reproducible, and sensitive, with the detection limit of 1 C. auris CFU/PCR. The performance of the C. auris real-time PCR assay was evaluated by using 623 surveillance samples, including 365 patient swabs and 258 environmental sponges. Real-time PCR yielded positive results from 49 swab and 58 sponge samples, with 89% and 100% clinical sensitivity with regard to their respective culture-positive results. The real-time PCR also detected C. auris DNA from 1% and 12% of swab and sponge samples with culture-negative results, indicating the presence of dead or culture-impaired C. auris. The real-time PCR yielded results within 4 h of sample processing, compared to 4 to 14 days for culture, reducing turnaround time significantly. The new real-time PCR assay allows for accurate and rapid screening of C. auris and can increase effective control and prevention of this emerging multidrug-resistant fungal pathogen in health care facilities.

Candida auris is a globally emerging yeast that causes outbreaks in health care settings and is often resistant to one or more classes of antifungal medications (1). Cases of C. auris with resistance to all three classes of commonly prescribed antifungal drugs (pan-resistance) have been reported in multiple countries (1). C. auris has been identified in the United States since 2016; the largest number (427 of 911 [47%]) of confirmed clinical cases reported as of October 31, 2019, have been reported in New York, where C. auris was first detected in July 2016 (1,2). As of June 28, 2019, a total of 801 patients with C. auris were identified in New York, based on clinical cultures or swabs of skin or nares obtained to detect asymptomatic colonization (3). Among these patients, three were found to have pan-resistant C. auris that developed after receipt of antifungal medications, including echinocandins, a class of drugs that targets the fungal cell wall. All three patients had multiple comorbidities and no known recent domestic or foreign travel. Although extensive investigations failed to document transmission of pan-resistant isolates from the three patients to other patients or the environment, the emergence of pan-resistance is concerning. The occurrence of these cases underscores the public health importance of surveillance for C. auris, the need for prudent antifungal prescribing, and the importance of conducting susceptibility testing on all clinical isolates, including serial isolates from individual patients, especially those treated with echinocandin medications. This report summarizes investigations related to the three New York patients with pan-resistant infections and the subsequent actions conducted by the New York State Department of Health and hospital and long-term care facility partners. Clinical C. auris cases were defined as those in which C. auris was identified in a clinical culture obtained to diagnose or treat disease. Screening cases were defined as those in which C. auris was identified by polymerase chain reaction testing and culture, or by culture only, of a sample from an axilla, groin, or nares swab obtained for the purpose of state public health surveillance (2). To assess ongoing colonization with C. auris, additional swabs were collected over time from patients colonized with C. auris. Wadsworth Center, the New York State public health laboratory, conducted testing to confirm presumptive C. auris isolates from various health care facilities in New York during

SummaryThe pathogenic yeast Cryptococcus neoformans ( Cn ) var. gattii causes meningoencephalitis in healthy individuals, unlike the better known Cn varieties grubii and neoformans , which are common in immunocompromised individuals. The virulence determinants and mechanisms of host predilection are poorly defined for var. gattii . The present study focused on the characterization of a Cu,Zn superoxide dismutase ( SOD1 ) gene knock-out mutant constructed by developing a DNA transformation system. The sod1 mutant was highly sensitive to the redox cycling agent menadione, and showed fragmentation of the large vacuole in the cytoplasm, but no other defects were seen in growth, capsule synthesis, mating, sporulation, stationary phase survival or auxotrophies for sulphurcontaining amino acids. The sod1 mutant was markedly attenuated in virulence in a mouse model, and it was significantly susceptible to in vitro killing by human neutrophils (PMNs). The deletion of SOD1 also resulted in defects in the expression of a number of virulence factors, i.e. laccase, urease and phospholipase. Complementation of the sod1 mutant with SOD1 resulted in recovery of virulence factor expression and menadione resistance, and in restoration of virulence. Overall, these results suggest that the antioxidant function of Cu,Zn SOD is critical for the pathogenesis of the fungus, but is dispensable in its saprobic life. This report constitutes the first instance in which superoxide dismutase has been directly implicated in the virulence of a fungal pathogen.

Cryptococcosis is a major fungal disease caused by members of the Cryptococcus gattii and Cryptococcus neoformans species complexes. After more than 15 years of molecular genetic and phenotypic studies and much debate, a proposal for a taxonomic revision was made.

A molecular analysis of pheromone genes showed a notable prevalence of Cryptococcus gattii isolates from AIDS patients in southern California.

Cryptococcus gattii, an emerging fungal pathogen of humans and animals, is found on a variety of trees in tropical and temperate regions. The ecological niche and virulence of this yeast remain poorly defined. We used Arabidopsis thaliana plants and plant-derived substrates to model C. gattii in its natural habitat. Yeast cells readily colonized scratch-wounded plant leaves and formed distinctive extracellular fibrils (40–100 nm diameter ×500–3000 nm length). Extracellular fibrils were observed on live plants and plant-derived substrates by scanning electron microscopy (SEM) and by high voltage- EM (HVEM). Only encapsulated yeast cells formed extracellular fibrils as a capsule-deficient C. gattii mutant completely lacked fibrils. Cells deficient in environmental sensing only formed disorganized extracellular fibrils as apparent from experiments with a C. gattii STE12α mutant. C. gattii cells with extracellular fibrils were more virulent in murine model of pulmonary and systemic cryptococcosis than cells lacking fibrils. C. gattii cells with extracellular fibrils were also significantly more resistant to killing by human polymorphonuclear neutrophils (PMN) in vitro even though these PMN produced elaborate neutrophil extracellular traps (NETs). These observations suggest that extracellular fibril formation could be a structural adaptation of C. gattii for cell-to-cell, cell-to-substrate and/or cell-to- phagocyte communications. Such ecological adaptation of C. gattii could play roles in enhanced virulence in mammalian hosts at least initially via inhibition of host PMN– mediated killing.

The sexual mating of the pathogenic yeast Cryptococcus neoformans is important for pathogenesis studies because the fungal virulence is linked to the ␣ mating type (MAT␣). We characterized C. neoformans mating pheromones (MF␣ 1 and MFa1) from 122 strains to understand intervariety hybridization or mating and intervariety virulence. MF␣ 1 in three C. neoformans varieties showed (a) specific nucleotide polymorphisms, (b) different copy numbers and chromosomal localizations, and (c) unique deduced amino acids in two geographic populations of C. neoformans var. gattii. MF␣ 1 of different varieties cross-hybridized in Southern hybridizations. Their phylogenetic analyses showed purifying selection (neutral evolution). These observations suggested that MAT␣ strains from any of the three C. neoformans varieties could mate or hybridize in nature with MATa strains of C. neoformans var. neoformans. A few serotype A/D diploid strains provided evidence for mating or hybridization, while a majority of A/D strains tested positive for haploid MF␣ 1 identical to that of C. neoformans var. grubii. MF␣ 1 sequence and copy numbers in diploids were identical to those of C. neoformans var. grubii, while their MFa1 sequences were identical to those of C. neoformans var. neoformans; thus, these strains were hybrids. The mice survival curves and histological lesions revealed A/D diploids to be highly pathogenic, with pathogenicity levels similar to that of the C. neoformans var. grubii type strain and unlike the low pathogenicity levels of C. neoformans var. neoformans strains. In contrast to MF␣ 1 in three varieties, MFa1 amplicons and hybridization signals could be obtained only from two C. neoformans var. neoformans reference strains and eight A/D diploids. This suggested that a yet undiscovered MFa pheromone(s) in C. neoformans var. gattii and C. neoformans var. grubii is unrelated to, highly divergent from, or rarer than that in C. neoformans var. neoformans. These observations could form the basis for future studies on the role of intervariety mating in C. neoformans biology and virulence.Cryptococcus neoformans causes cryptococcal meningoencephalitis in healthy and immunocompromised individuals. The fungus has two mating types (mating type ␣ [MAT␣] and MATa), three varieties (C. neoformans var. neoformans, C. neoformans var. gattii, and C. neoformans var. grubii), and five serotypes (A, B, C, D, and A/D). C. neoformans var. grubii is most common in cryptococcosis among immunocompromised patients; the isolates are usually serotype A, MAT␣. This variety apparently reproduces asexually in nature, as indicated by the rarity of fertile MATa isolates (9,19,29). Sexual mating is seen in the laboratory both in C. neoformans var. neoformans (serotype D) and C. neoformans var. gattii (serotype B or C). The latter two varieties also show laboratory cross-hybridization; thus, their teleomorphs are classified as Filobasidiella neoformans var. neoformans and F. neoformans var. bacillispora (30). Currently, C. neoformans sexual mating is being ...