Aspergillus collected in specific indoor settings: their molecular identification and susceptibility pattern

The bioaerosols generated from the sludge treatment process: Bacterial and fungal variation characteristics, source tracking, and risk assessment

Bioaerosols generated from sludge treatment processes in wastewater treatment plants (WWTPs) may spread infectious diseases. This study investigated the generation characteristics, source, and associated risks of bioaerosols produced during sludge treatment processes. The results showed that the concentration range of total suspended particles was 49 ± 3 to 354 ± 10 μg/m3, and the primary water-soluble ions in bioaerosols were NH4+, SO42- and Cl-. The bacterial concentration in bioaerosols was 50 ± 5 to 1296 ± 261 CFU/m3, with the highest concentration in the biochemical reaction tank. The dominant bacteria in bioaerosols included Bacteroides, Cetobacterium, Romboutsia, Lactobacillus and Turicibacter, while the dominant fungi were Aspergillus, Alternaria, Cladosporium and Fusarium. Pathogenic microorganisms such as Escherichia and Aspergillus were detected in all treatment processes. The results of principal component analysis showed that the bacterial composition in bioaerosols was similar of different technological processes, while the fungal species composition was different. The dominant microbial composition of sludge and bioaerosols was relatively close. The Source Tracker results indicated that sludge was the main source of airborne bacteria in the sludge dewatering house, as well as the main source of airborne fungi in the plate-frame pressure filtration tank and the sloping plate sedimentation tank. The non-carcinogenic risk in each stage was low (1.22 × 10-9-3.99 × 10-2). However, Bugbase phenotype prediction results showed that the bioaerosols in the anaerobic sedimentation tank may have potential pathogenicity. Therefore, the management and control of bioaerosols from the sludge treatment should be strengthened.

Presence of Aspergillus fumigatus with the TR34/L98H Cyp51A mutation and other azole-resistant aspergilli in the air of a zoological park

Antifungal-resistant fungi, including Aspergillus fumigatus and other Aspergillus species, pose an urgent threat to human and animal health. Furthermore, the environmental route of azole resistance selection due to the widespread use of azole fungicides in crop protection and other applications is a major public health issue. Although environmental surveillance of fungi is frequently performed in many zoological parks and wildlife rehabilitation centers, the antifungal susceptibility of recovered isolates is only rarely analyzed, which precludes a clear assessment of the threat posed by these fungi to captive animals. In this study, we assessed the presence of airborne azole-resistant Aspergillus spp., including the so-called 'cryptic species' (i.e., species which are phenotypically similar to more well-known aspergilli but clearly constitute different phylogenetic lineages) in a zoological park located in the city of Madrid, Spain. In general, our results revealed a low prevalence A. fumigatus and cryptic aspergilli with decreased susceptibility to azoles. However, we detected an A. fumigatus isolate with the TR34/L98H mutation in the gene encoding the lanosterol 14α-demethylase (Cyp51A), consisting of a tandem repeat of 34 base pairs in the promoter region and a lysine to histidine substitution at codon 98. Notably, this TR34/L98H mutation has been linked to the environmental route of azole resistance selection, thus highlighting the 'One Health' dimension of the emerging problem of antifungal resistance. In this context, continuous environmental surveillance of azole-resistant aspergilli in zoological parks and other similar animal facilities is recommended.

Novel Treatment Approach for Aspergilloses by Targeting Germination

Germination of conidia is an essential process within the Aspergillus life cycle and plays a major role during the infection of hosts. Conidia are able to avoid detection by the majority of leukocytes when dormant. Germination can cause severe health problems, specifically in immunocompromised people. Aspergillosis is most often caused by Aspergillus fumigatus (A. fumigatus) and affects neutropenic patients, as well as people with cystic fibrosis (CF). These patients are often unable to effectively detect and clear the conidia or hyphae and can develop chronic non-invasive and/or invasive infections or allergic inflammatory responses. Current treatments with (tri)azoles can be very effective to combat a variety of fungal infections. However, resistance against current azoles has emerged and has been increasing since 1998. As a consequence, patients infected with resistant A. fumigatus have a reported mortality rate of 88% to 100%. Especially with the growing number of patients that harbor azole-resistant Aspergilli, novel antifungals could provide an alternative. Aspergilloses differ in defining characteristics, but germination of conidia is one of the few common denominators. By specifically targeting conidial germination with novel antifungals, early intervention might be possible. In this review, we propose several morphotypes to disrupt conidial germination, as well as potential targets. Hopefully, new antifungals against such targets could contribute to disturbing the ability of Aspergilli to germinate and grow, resulting in a decreased fungal burden on patients.

Electrostatic Dust Cloth: A Useful Passive Sampling Method When Assessing Exposure to Fungi Demonstrated in Studies Developed in Portugal (2018–2021)

Electrostatic dust cloths (EDC) have been widely used for microbiologic contamination assessment in different indoor and occupational environments. This paper reviews sixteen studies performed in Portugal between 2018 and 2021 for evaluating the exposure to microbiological agents and focusing on fungi using EDC as a passive sampling method. The findings suggest that EDC can be applied as a screening method for particulate matter-exposure assessment and as a complementary method to characterize microbial exposures in occupational environments. Overall, EDC should be included, side by side with other sampling methods, in sampling campaigns focused on exposure assessments due to the advantages such as the straightforward extraction protocol favoring the employment of different assays, which allows us to assess exposure to a wide range of microbial agents, and presents higher accuracy regarding the fungal diversity.

Cytotoxicity of Aspergillus Section Fumigati Isolated from Health Care Environments

This study analyzed 57 Aspergillus section Fumigati (AF) isolates collected by active and passive sampling (N = 450) in several health care facilities and from biological sampling of health care workers (N = 25) and controls (N = 22) in Portugal. All isolates were cultured in different media and screened for azole resistance. Cytotoxicity was assessed for 40 isolates in lung epithelial cells and kidney cells using the MTT assay. Aspergillus section Fumigati was prevalent in the health care facilities and in nasal swabs from health care workers and controls. All AF isolates reduced cell viability and presented medium to high cytotoxicity, with cytotoxicity being significantly higher in A549 lung epithelial cells. The cytotoxicity of isolates from air and nasal swab samples suggested the inhalation route as a risk factor. Notably, 42% of AF isolates exhibited a pattern of reduced susceptibility to some of the most used antifungals available for the treatment of patients infected with these fungi. In sum, the epidemiology and clinical relevance of Aspergillus section Fumigati should continue to be addressed. A deeper understanding of the mechanisms underlying Aspergillus-mediated cytotoxicity is necessary.

Loading Rates of Dust and Bioburden in Dwellings in an Inland City of Southern Europe

Sampling campaigns indoors have shown that occupants exposed to contaminated air generally exhibit diverse health outcomes. This study intends to assess the deposition rates of total settleable dust and bioburden in the indoor air of dwellings onto quartz fiber filters and electrostatic dust collectors (EDCs), respectively. EDC extracts were inoculated onto malt extract agar (MEA) and dichloran glycerol (DG18) agar-based media used for fungal contamination characterization, while tryptic soy agar (TSA) was applied for total bacteria assessment, and violet red bile agar (VRBA) for Gram-negative bacteria. Azole-resistance screening and molecular detection by qPCR was also performed. Dust loading rates ranged from 0.111 to 3.52, averaging 0.675 μg cm−2 day−1. Bacterial counts ranged from undetectable to 16.3 colony-forming units (CFU) m−2 day−1 and to 2.95 CFU m−2 day−1 in TSA and VRBA, respectively. Fungal contamination ranged from 1.97 to 35.4 CFU m−2 day−1 in MEA, and from undetectable to 48.8 CFU m−2 day−1 in DG18. Penicillium sp. presented the highest prevalence in MEA media (36.2%) and Cladosporium sp. in DG18 (39.2%). It was possible to observe: (a) settleable dust loadings and fungal contamination higher in dwellings with pets; (b) fungal species considered indicators of harmful fungal contamination; (c) Aspergillus section Candidi identified in supplemented media with voriconazole and posaconazole; (d) specific housing typologies and (e) specific housing characteristics influencing the microbial contamination.