Water quality and antifungal susceptibility of opportunistic yeast pathogens from rivers

Detection and taxonomic identification of emerging pathogenic yeasts in surface waters from Lagoon Systems in Rio de Janeiro, Brazil

This study aimed to detect and identify emerging pathogenic yeasts in surface waters from two Lagoon Systems in Rio de Janeiro, Brazil, by polyphasic taxonomy. The monitoring of potentially pathogenic fungi in aquatic environments, especially in regions impacted by human actions, is highlighted in this study as one of the axes of the One Health approach. Water samples were collected, and after isolation, fungi were identified by polyphasic taxonomy, including MALDI-TOF-MS, which is also used for bacteria identification. Our results describe the physicochemical parameters of the surface water of these lagoons and reveal a significant diversity of yeast species, some of which are known to exhibit pathogenic potential and resistance to common antifungal treatments, as well as bacteria with resistance profiles to several currently used antibiotics. We conclude that Jacarepaguá Lagoon is the most impacted compared to Piratininga Lagoon; however, we highlight the urgent need for targeted interventions to mitigate pollution in both Lagoons, reinforcing the value of long-term surveillance in both ecosystems. We believe that monitoring emerging species is as critical as analyzing traditional water quality parameters. Early detection of resistant or invasive pathogens in aquatic ecosystems can prevent disease outbreaks, protect biodiversity, and mitigate public health risks, preventing loss of life, and optimizing public healthcare system expenditures.

Pathogenic Aspergillus spp. and Candida spp. in coastal waters from southern Brazil: an one health approach

Aspergillus and Candida are ubiquitous fungi included in the group of high priority in the World Health Organization list of fungal pathogens. They are found in various ecosystems and the environmental role in increasing the resistance to antifungals has been shown. Thus, we aimed to determine the occurrence of Aspergillus spp. and Candida spp. pathogenic species in water samples from a coastal ecosystem from southern Brazil, and its antifungal susceptibility profile. Water samples were collected monthly at three environmental sites, over 25 months. Abiotic parameters of the water samples were analyzed as well as antifungal susceptibility. Aspergillus spp. and Candida spp. were detected in 44% (n = 33/75) and 40% (n = 30/75) respectively of the samples, totaling 67 and 96 isolates. Section Fumigati and C. parapsilosis were the most section/species isolated. Triazole resistance was detected in 3% of the Aspergillus spp. (2/67) and in 1% of the Candida spp. (1/96) isolates. Our study contributes with data showing that coastal aquatic environments can serve as a source of infection of resistant fungal isolates, proving the need for environmental surveillance and monitoring of fungal resistance in the One Health perspective.

A one health roadmap towards understanding and mitigating emerging Fungal Antimicrobial Resistance: fAMR

The emergence of fungal antimicrobial resistance-fAMR-is having a growing impact on human and animal health, and food security. This roadmap charts inter-related actions that will enhance our ability to mitigate the risk of fAMR. As humanity's reliance on antifungal chemicals escalates, our understanding of their one-health consequences needs to scale accordingly if we are to protect our ability to manage the global spectrum of fungal disease sustainably.

Physiological responses contributing to multiple stress tolerance in Pichia kudriavzevii with potential enhancement for ethanol fermentation

Economically feasible ethanol production requires efficient hydrolysis of lignocellulosic biomass and high-temperature processing to enable simultaneous saccharification and fermentation. During the lignocellulolysic hydrolysate, the yeast must encounter with a multiple of inhibitors such as heat and furfural. To solve this problem, a potential fermentative yeast strain that tolerated simultaneous multistress and enhance ethanol concentration was investigated. Twenty yeast isolates were classified into two major yeast species, namely Pichia kudriavzevii (twelve isolates) and Candida tropicalis (eight isolates). All P. kudriavzevii isolates were able to grow at high temperature (45 °C) and exhibited stress tolerance toward furfural. Among P. kudriavzevii isolates, NUCG-S3 presented the highest specific growth rate under each stress condition of heat and furfural, and multistress. Morphological changes in P. kudriavzevii isolates (NUCG-S2, NUCG-S3, NUKL-P1, NUKL-P3, and NUOR-J1) showed alteration in mean cell length and width compared to the non-stress condition. Ethanol production by glucose was also determined. The yeast strain, NUCG-S3, gave the highest ethanol concentrations at 99.46 ± 0.82, 62.23 ± 0.96, and 65.80 ± 0.62 g/l (P < 0.05) under temperature of 30 °C, 40 °C, and 42 °C, respectively. The tolerant isolated yeast NUCG-S3 achieved ethanol production of 53.58 ± 3.36 and 48.06 ± 3.31 g/l (P < 0.05) in the presence of 15 mM furfural and multistress (42 °C with 15 mM furfural), respectively. Based on the results of the present study, the novel thermos and furfural-tolerant yeast strain P. kudriavzevii NUCG-S3 showed promise as a highly proficient yeast for high-temperature ethanol fermentation.

Water Quality, Heavy Metals, and Antifungal Susceptibility to Fluconazole of Yeasts from Water Systems

Aquatic environments could be reservoirs of pathogenic yeasts with acquired antifungal resistance. The susceptibility to antifungal agents of yeasts present in the wastewater and natural waters of the city of Cali was evaluated. Samples were taken from two types of water: drinking water (Meléndez River, drinking water treatment plant "Puerto Mallarino" in the Cauca River) and wastewater (South Channel of the Cauca River, "Cañaveralejo-PTAR" wastewater treatment plant). Physico-chemical parameters, heavy metal concentration, and yeast levels were determined using standard procedures. Yeasts were identified using API 20 C AUX (BioMérieux) and sequence analysis of the ITS1-5.8S-ITS2 and D1/D2 regions of the large subunit of the ribosome. Susceptibility assays against fluconazole and amphotericin B using the minimum inhibitory concentration (MIC) test were determined using the microdilution method. The influence of physico-chemical parameters and heavy metals was established using principal component analysis (PCA). Yeast counts were higher at WWTP "PTAR" and lower at Melendez River, as expected. A total of 14 genera and 21 yeast species was identified, and the genus Candida was present at all locations. Susceptibility tests showed a 32.7% resistance profile to fluconazole in the order DWTP "Puerto Mallarino = WWTP "PTAR" > South Channel "Navarro". There were significant differences (p < 0.05) in the physico-chemical parameters/concentration of heavy metals and yeast levels between the aquatic systems under study. A positive association was observed between yeast levels and total dissolved solids, nitrate levels, and Cr at the "PTAR" WWTP; conductivity, Zn, and Cu in the South Channel; and the presence of Pb in the "Puerto Mallarino" DWTP. Rhodotorula mucilaginosa, Candida albicans, and Candida sp. 1 were influenced by Cr and Cd, and Diutina catelunata was influenced by Fe (p < 0.05). The water systems explored in this study showed different yeast levels and susceptibility profiles, and, therefore, possible genetic differences among populations of the same species, and different physico-chemical and heavy metals concentrations, which were probably modulating the antifungal-resistant yeasts. All these aquatic systems discharge their content into the Cauca River. We highlight the importance to further investigate if these resistant communities continue to other locations in the second largest river of Colombia and to determine the risk posed to humans and animals.

Communities of culturable yeasts and yeast-like fungi in oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar

This report is the first investigation of yeast biodiversity from the oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar. Yeasts and yeast-like fungi, were cultured from seawater sampled at 13 coastal areas surrounding Qatar over a period of 2 years (December 2013-September 2015). Eight hundred and forty-two isolates belonging to 82 species representing two phyla viz., Ascomycota (23 genera) and Basidiomycota (16 genera) were identified by molecular sequencing. The results indicated that the coastal waters of the Qatari oligotrophic marine environment harbor a diverse pool of yeast species, most of which have been reported from terrestrial, clinical and aquatic sources in various parts of the world. Five species, i.e., Candida albicans, C. parapsilosis, C. tropicalis, Pichia kudriavzevii and Meyerozyma guilliermondii (n = 252/842; 30% isolates) are known as major opportunistic human pathogens. Fifteen species belonging to nine genera (n = 498/842; 59%) and 12 species belonging to seven genera (n = 459/842; 55%) are hydrocarbon degrading yeast and pollution indicator yeast species, respectively. Ascomycetous yeasts were predominant (66.38%; 559/842) as compared to their basidiomycetous counterparts (33.6%; 283/842). The most isolated yeast genera were Candida (28%; 236/842) (e.g., C. aaseri, C. boidinii, C. glabrata, C. intermedia, C. oleophila, C. orthopsilosis, C. palmioleophila, C. parapsilosis, C. pseudointermedia, C. rugopelliculosa, C. sake, C. tropicalis and C. zeylanoides), Rhodotorula (12.7%; 107/842), Naganishia (8.4%; 71/842), Aureobasidium (7.4%; 62/842), Pichia (7.3%; 62/842), and Debaryomyces (6.4%; 54/842). A total of eleven yeast species ( n = 38) isolated in this study are reported for the first time from the marine environment. Chemical testing demonstrated that seven out of the 13 sites had levels of total petroleum hydrocarbons (TPH) ranging from 200 to 900 µg/L, whereas 6 sites showed higher TPH levels (> 1000-21000 µg/L). The results suggest that the yeast community structure and density are impacted by various physico-chemical factors, namely total organic carbon, dissolved organic carbon and sulphur.

Collateral consequences of agricultural fungicides on pathogenic yeasts: A One Health perspective to tackle azole resistance

Candida and Cryptococcus affect millions of people yearly, being responsible for a wide array of clinical presentations, including life-threatening diseases. Interestingly, most human pathogenic yeasts are not restricted to the clinical setting, as they are also ubiquitous in the environment. Recent studies raise concern regarding the potential impact of agricultural use of azoles on resistance to medical antifungals in yeasts, as previously outlined with Aspergillus fumigatus. Thus, we undertook a narrative review of the literature and provide lines of evidence suggesting that an alternative, environmental route of azole resistance, may develop in pathogenic yeasts, in addition to patient route. However, it warrants sound evidence to support that pathogenic yeasts cross border between plants, animals and humans and that environmental reservoirs may contribute to azole resistance in Candida or other yeasts for humans. As these possibilities could concern public health, we propose a road map for future studies under the One Health perspective.

Antifungal agents, yeast abundance and diversity in surface water: Potential risks to water users

South African surface waters are subject to various forms of pollution. Recent findings in aquatic systems suggest an association exists between yeast diversity, chemical pollutants and land coverage, which are important water quality determinants. Yeast abundance and diversity, as well as antifungal agents in two river systems in South Africa, were investigated and related to the existing land coverage. Yeast abundance and diversity were determined from environmental DNA by quantitative polymerase chain reaction and next-generation sequencing, respectively, of the 26S ribosomal ribonucleic acid (rRNA) gene. Antifungal agents were qualitatively and/or quantitatively detected by ultra-high-pressure liquid chromatography-mass spectrometry. Analyses of 2 031 714 high-quality 26S rRNA sequences yielded 5554 amplicon sequence variants (ASVs)/species. ASV richness and Shannon-Wiener index of diversity reflected the southward flow of the river with higher values observed downstream compared to the upstream. Fluconazole concentrations were quantifiable in only two samples; 178 and 271 ng L^-1. Taxonomically, at least 20 yeast species were detected, including the dominant Candida tropicalis, Cryptococcus spp. as well as the lesser dominant Bensingtonia bomiensis, Fereydounia khargensis, Hericium erinaceus, Kondoa changbaiensi, Pseudozyma spp. and Sphacelotheca pamparum. The two dominant species are known opportunistic pathogens which had antifungal resistant traits in previous studies from the same rivers and therefore is a public health threat. The present study provides further evidence that yeasts should be included as part of water quality parameters, especially in developing countries where much of the population are economically disadvantaged, and also immunocompromised due to age and disease.

Microbial Communities' Characterization in Urban Recreational Surface Waters Using Next Generation Sequencing

Microbial communities in surface waters used for recreational purposes are indicators of contamination and risk of contact with human pathogens. Hence, monitoring microbial communities in recreational waters is important for potential public health threats to humans. Such monitoring is rare in Colombia, even in its capital, Bogotá, the most populous city in the country. This city encompasses metropolitan and linear parks with recreational water bodies that are used frequently by the public, and the presence of pathogens can compromise the health of the citizens. Therefore, we examined the bacterial, and eukaryotic communities in urban recreational lakes (URL) in four metropolitan parks in Bogotá, Colombia. Samples from four metropolitan parks (Los Novios, Simon Bolivar, El Tunal, and Timiza) and one stream contaminated with sewage from a linear park (El Virrey) were collected. We used amplicon next-generation sequencing of the 16S-rRNA gene and 18S-rRNA gene to characterize microbial communities followed by bioinformatics analyses. In addition, general water quality parameters-pH, hardness, acidity, alkalinity, dissolved oxygen, and nitrites-were recorded using a commercial kit. Genera of pathogens, including Legionella, Pseudomonas, Mycobacterium, Candida, and Naegleria, were found in lake waters. The stream El Virrey was, however, the only surface water that showed an abundance of fecal bacteria, often associated with low oxygen concentrations. All water bodies showed a predominance of fungal phyla, except for the lake at Timiza. This lake showed the highest pH, and its ecological dynamics are likely different from other water bodies. Likewise, some URLs displayed a greater abundance of cyanobacteria, including toxin-producing species. Algal genera associated with eutrophication were predominant among primary producing microorganisms. This study shows for the first time the description of the bacterial and eukaryotic communities of some URLs and a stream in Bogotá. The URLs and the stream harbored various pathogens that might pose a risk to the citizen's health.