Occurrence of fungi in dialysis water and dialysate from eight haemodialysis units in central Italy

Fungal contamination of the water distribution system of a tertiary hospital water supply system in a resource-limited setting

Background

Fungal contamination of hospital water distribution systems has been implicated in outbreaks of healthcare-associated infections.

Objectives

To evaluate the prevalence of fungi in the water distribution system of a tertiary hospital in Nigeria.

Design

This was a descriptive cross-sectional study.

Methods

Swabs and water samples were collected from taps and faucets in the hospital categorized into low (Accidents and Emergency Unit, Children Emergency Unit, Acute Stroke Unit and the 24 in-patient hospital wards) and high-risk (Renal Dialysis Unit, Central Sterile Services Department, Theatres and Intensive Care Units (ICUs)) units based on the vulnerability of patients being managed there. The membrane filtration method for water analysis was used. Where possible, isolates cultured were identified to species level. In total, 105 water and 49 swab samples were collected for analysis.

Results

All analysed water samples grew fungi. A total of 289 (high-risk; n = 178; low-risk; n = 111) and 76 fungi isolates were recorded from water and swab samples, respectively, with 31 different species identified. Aspergillus was the most predominant genus with five different species: Aspergillus niger (9.9%), terreus (4.4%), flavus (3.3%), fumigatus (8.8%) and versicolor (2.20%) isolated. Twenty-five and 18 species of fungi were identified in the low and high-risk units, respectively. The labour ward (n = 46; 25.8%) and modular theatre (n = 47; 42.3%) were the most contaminated units. Cladosporium spp. and Paecilomyces spp. were the most frequently isolated fungi in the low and high-risk units, respectively. The dialysis centre (n = 9; 8.1%) and renal transplant theatre (n = 7; 6.31%) had the lowest contamination rates in the high-risk units. Aspergillus niger, Cephalosporium curtipes, Penicillium chrysogenum and Penicillium glabrum were each identified in 4/6 units from which swabs were taken. The facility had no documented protocol for its water safety and quality.

Conclusion

Our data reveal a high rate of contamination of hospital water sources by fungi, some of which are known to cause life-threatening infections. For better water treatment and water tank cleaning and disinfection, a standard protocol is advised. Ensuring that the water distribution systems in hospital settings are free of fungal contaminants is important to prevent the possibility of waterborne mycosis outbreaks.

Fungal identification in the air and water of a hemodialysis unit in Brazil

The presence of fungi in healthcare settings, including hemodialysis units, represents a significant risk for immunocompromised patients. This study aimed to investigate the occurrence of fungi in the air and water of a hemodialysis unit located in a tertiary public hospital in Maceió, Alagoas, Brazil. Over a period of three consecutive months, monthly air samples were collected and analyzed using the spontaneous sedimentation technique on Petri dishes containing Sabouraud Dextrose Agar (SDA). Simultaneously, water samples (100 mL) were collected from four specific water distribution points and subjected plating on SDA. Fungi were phenotypically identified based on their macroscopic and microscopic characteristics. In total, 498 colony-forming units (CFUs) of fungi were isolated, with 86 CFUs originating from the air and 412 CFUs from the water. Regarding the water samples, a higher concentration of fungal CFUs was observed in the potable water from the supply network (229 CFUs). Unexpectedly, 23 CFUs were identified in the reverse osmosis samples and 11 CFUs in the storage tank, which are post-treatment points where the presence of microorganisms is not desired. The fungus Cladosporium spp. was the most prevalent in both air and water samples, followed by Penicillium spp. in the air and Rhodotorula spp. in the water. These findings underscore the need to implement effective control and monitoring measures for fungi in the hemodialysis unit to ensure patient safety.

Detection of trizole contaminated waste water using biocatalyst and effective biodegradation potential of flubendiamide

Flubendiamide is a new class of chemical pesticide with broad spectrum activity against lepidopteran pests. Due to limited approach and high specificity towards various non targeted organisms, the unrestricted application of this pesticide as a prominent alternate for organochlorine and organophosphate pesticides, causing serious environmental pollution. In this study, wastewater was used for the determination of microbial strains and pesticide degrading fungi. Microbial population and flubendiamide resistant fungal strains were characterized using enriched medium. Aerobic bacteria (6.38 ± 0.23 log CFU/mL), nitrifying bacteria (2.73 ± 0.31 CFU/mL), Lactobaillus (0.72 ± 0.03 log CFU/mL), actinomycetes (5.36 ± 0.27 log CFU/mL) and fungi (4.79 ± 0.22 log CFU/mL) were detected. The prominent fungi genera were, Fusarium, Trichoderma, Cladophialophora, Paecilomyces, Talaromyces, Penicillium, Aspergillus, Candida, Phyllosticta, Mycosphaerella, Ochroconis, and Mucor. Minimum inhibitory concentration of the rapidly growing organism (FR04) revealed its ability to tolerate up to 1250 mg/L flubendiamide concentration. Morphological, biochemical and molecular analysis revealed that the strain was Aspergillus terreus FR04. The residual pesticide was detected using a High Performance Liquid Chromatography (HPLC). High performance liquid chromatography analysis revealed that 89 ± 1.9% pesticide removal efficiency was observed in strain FR04 at optimized culture conditions (96 h, pH 6.5, 30 °C and 300 mg/L pesticide concentration). The strain FR04 degraded pollutants from the wastewater and improved water quality. A. terreu sFR04 is an indigenous fungus and has the ability to degrade trizole pesticides from the wastewater significantly.

Fungi in dialysis water and dialysate: occurrence, susceptibility to antifungal agents and biofilm production capacity

The aim of this study was to investigate the occurrence of fungi in dialysis water and dialysate, in addition to evaluating the susceptibility to antifungals and the biofilm production capacity of isolated microorganisms. The samples were collected in three hemodialysis units in Bauru (Brazil), every 15 days (July 2017-June 2018) at post-reverse osmosis, reuse, and dialysate points. The fungi were isolated by spread plate on Sabouraud dextrose agar. Filamentous fungi were phenotypically identified and yeasts were subjected to molecular evaluation of the ITS region. Susceptibility test to antifungals was carried out by the broth microdilution method and biofilm production capacity was evaluated in microtiter plates using crystal violet staining. Fungi were isolated in 52/216 (24.1%) samples, with an average count of 16.3 (10-40) CFU/mL. Overall, 61 microorganisms were identified, with 54 (88.5%) filamentous fungi and 7 (11.5%) yeasts. The main genera included were Penicillium, Cladosporium, Scedosporium, Rhinocladiella, Fusarium, and Emmonsia. Most isolates showed high values of minimum inhibitory concentration for 5-flucytosine and fluconazole and 35/45 (77.8%) isolates were classified as strong producers of biofilm. In order to increase the safety of the dialysis process, the adoption of control measures and monitoring of fungi in hemodialysis fluids is suggested.

Disinfectants in a Hemodialysis Setting: Antifungal Activity Against Aspergillus and Fusarium Planktonic and Biofilm Cells and the Effect of Commercial Peracetic Acid Residual in Mice

Aspergillus and Fusarium cause a broad spectrum of infections in humans, mainly in immunocompromised patients. Among these, patients undergoing hemodialysis are highly susceptible to infections, requiring a constant and adequate environmental disinfection program. Nevertheless, monitoring the residual disinfectants can contribute to the morbidity and mortality reduction in these patients. Here, we evaluated the susceptibility of Aspergillus spp. (n=19) and Fusarium spp. (n=13) environmental isolates against disinfectants (acetic acid, citric acid, peracetic acid, sodium hypochlorite, and sodium metabisulphite) at different concentrations and time exposures. Also, we investigated the in vivo toxicity of the peracetic acid residual concentration in mice. Fusarium isolates were identified by F. equiseti, F. oxysporum and F. solani while Aspergillus presented clinically relevant species (A. fumigatus, A. niger and A. terreus) and environmental ones. Against planktonic cells, only two disinfectants (acetic acid and sodium hypochlorite) showed a fungicidal effect on Fusarium spp., while only one (sodium hypochlorite) was effective against Aspergillus spp. Both fungi formed robust in vitro biofilms with large amounts of the extracellular matrix, as evidenced by electron micrographs. Exposure of fungal biofilms to disinfectants showed sensitivity to three (acetic, citric, and peracetic acids), although the concentrations and times of exposure varied according to the fungal genus. Mice exposure to the residual dose of peracetic acid during 60 weeks showed anatomopathological, hematological, and biochemical changes. The implementation of news control measures and those that already exist can help reduce infections, the second cause of death and morbidity in these patients, besides providing safety and well-being to them, a priority of any quality health program.

Occurrence of filamentous fungi in drinking water: their role on fungal-bacterial biofilm formation

Water is indispensable to life and safe and accessible supply must be available to all. The presence of microorganisms is a threat to this commitment. Biofilms are the main reservoir of microorganisms inside water distribution systems and they are extremely ecologically diverse. Filamentous fungi and bacteria can coexist inside these systems forming inter-kingdom biofilms. This review has the goal of summarizing the most relevant and recent reports on the occurrence of filamentous fungi in water distribution systems along with the current knowledge and gaps about filamentous fungal biofilm formation. Special focus is given on fungal-bacterial interactions in water biofilms.

Opportunistic Water-Borne Human Pathogenic Filamentous Fungi Unreported from Food

Clean drinking water and sanitation are fundamental human rights recognized by the United Nations (UN) General Assembly and the Human Rights Council in 2010 (Resolution 64/292). In modern societies, water is not related only to drinking, it is also widely used for personal and home hygiene, and leisure. Ongoing human population and subsequent environmental stressors challenge the current standards on safe drinking and recreational water, requiring regular updating. Also, a changing Earth and its increasingly frequent extreme weather events and climatic changes underpin the necessity to adjust regulation to a risk-based approach. Although fungi were never introduced to water quality regulations, the incidence of fungal infections worldwide is growing, and changes in antimicrobial resistance patterns are taking place. The presence of fungi in different types of water has been thoroughly investigated during the past 30 years only in Europe, and more than 400 different species were reported from ground-, surface-, and tap-water. The most frequently reported fungi, however, were not waterborne, but are frequently related to soil, air, and food. This review focuses on waterborne filamentous fungi, unreported from food, that offer a pathogenic potential.

Yeast isolation and identification in water used in a Brazilian hemodialysis unit by classic microbiological techniques and Raman spectroscopy

The use of poorly treated water in hemodialysis centers may lead to fungal contamination, which poses a serious threat to immunologically debilitated hemodialysis patients. This study aimed to isolate and identify yeast species in the water of a Brazilian hemodialysis center by using classic microbiological techniques and Raman spectroscopy. For 12 months, a total of 288 water samples were collected from different points of the hemodialysis treatment distribution center. One hundred and forty-six yeast species were isolated and identified in the samples that tested positive for the presence of yeasts such as Candida parapsilosis (100 isolates, or 68.50%), C. guilliermondii (17 isolates, or 11.65%), Rhodotorula mucilaginosa (23 isolates, or 15.75%), R. glutinis (three isolates, or 2.05%), and Trichosporon inkin (three isolates, or 2.05%). Yeast susceptibility to the antifungal fluconazole was also assayed. Only two C. guilliermondii isolates were resistant to fluconazole: the minimal inhibitory concentrations were higher than 64 μg/mL. The different yeast species present in the water of a Brazilian hemodialysis center call for more effective water disinfection procedures in this unit. Raman spectroscopy is an excellent tool to identify yeast species and is potentially applicable in routine water monitoring in hemodialysis units.

Ultraviolet germicidal irradiation in tap water contaminated by Aspergillus spp

We investigated the effect of ultraviolet germicidal irradiation (UVI) from a low-pressure mercury lamp on several pathogenic Aspergillus spp. including A. flavipes, A. flavus, A. fumigatus, A. glaucus, A. nidulans, A. niger, A. terreus, A. ustus and A. versicolor suspended in tap water under laboratory-scale conditions. It was shown that within 10 s of exposure, time species such as A. glaucus, A. niudulans and A. ustus were completely inactivated, while 40 s were needed for the elimination of all the species tested. A. flavus and A. niger were found to be less susceptible than other species. Based on these results we conclude that UV disinfection could effectively inactivate Aspergillus spp. in tap water. Such disinfection could be used to reduce potential exposure of high-risk patients to fungal aerosols, particularly in hospital settings, where point-of-use (POU) UV light devices could be installed to provide safe water at a very low cost.

Evaluation and control of microbial and chemical contamination in dialysis water plants of Italian nephrology wards

BACKGROUND

Patients receiving haemodialysis are exposed to a large volume of dialysis fluid. The Italian Society of Nephrology (ISN) has published guidelines and microbial quality standards on dialysis water (DW) and solutions to ensure patient safety.

AIM

To identify microbial and chemical hazards, and evaluate the quality of disinfection treatment in DW plants.

METHODS

In 2015 and 2016, water networks and DW plants (closed loop and online monitors) of nine dialysis wards of Italian hospitals, hosting 162 dialysis beds overall, were sampled on a monthly basis to determine the parameters provided by ISN guidelines. Chlorinated drinking water was desalinated by reverse osmosis and distributed to the closed loop which feeds all online monitors. Disinfection with peracetic acid was performed in all DW plants on a monthly basis.

FINDINGS

Over the 24-month study period, seven out of nine DW plants (78%) recorded negative results for all investigated parameters. Closed loop contamination with Burkholderia cepacia was detected in a DW plant from January 2015 to March 2015. Pseudomonas aeruginosa was isolated from March 2016 to May 2016 in the closed loop of another DW plant. These microbial contaminations were eradicated by shock disinfection with sodium hypochlorite and peracetic acid, followed by water flushing.

CONCLUSION

These results highlight the importance of chemical and physical methods of DW disinfection. The maintenance of control measures in water plants hosted in dialysis wards ensures a microbial risk reduction for all dialysis patients.

Fungi, Water Supply and Biofilms

Even though it has been studied for many years, water-related infectious risk still exists in both care and community environments due to the possible presence of numerous microorganisms such as bacteria, fungi and protists. People can be exposed directly to these microorganisms either through aerosols and water, after ingestion, inhalation, skin contact and entry through mucosal membranes, or indirectly usually due to pre-treatment of some medical devices. Species belonging to genera such as Aspergillus, Penicillium, Pseudallesheria, Fusarium, Cuninghamella, Mucor and in some particular cases Candida have been isolated in water from health facilities and their presence is particularly related to the unavoidable formation of a polymicrobial biofilm in waterlines. Fungi isolation methods are based on water filtration combined with conventional microbiology cultures and/or molecular approaches; unfortunately, these are still poorly standardized. Moreover, due to inappropriate culture media and inadequate sampling volumes, the current standardized methods used for bacterial research are not suitable for fungal search. In order to prevent water-related fungal risk, health facilities have implemented measures such as ultraviolet radiation to treat the input network, continuous chemical treatment, chemical or thermal shock treatments, or microfiltration at points of use. This article aims to provide an overview of fungal colonization of water (especially in hospitals), involvement of biofilms that develop in waterlines and application of preventive strategies.

Biodegradation of pesticides using fungi species found in the aquatic environment

Relatively limited attention has been given to the presence of fungi in the aquatic environment compared to their occurrence in other matrices. Taking advantage and recognizing the biodegradable capabilities of fungi is important, since these organisms may produce many potent enzymes capable of degrading toxic pollutants. Therefore, the aim of this study was to evaluate the potential ability of some species of filamentous fungi that occur in the aquatic environment to degrade pesticides in untreated surface water. Several laboratory-scale experiments were performed using the natural microbial population present in the aquatic environment as well as spiked fungi isolates that were found to occur in different water matrices, to test the ability of fungi to degrade several pesticides of current concern (atrazine, diuron, isoproturon and chlorfenvinphos). The results obtained in this study showed that, when spiked in sterile natural water, fungi were able to degrade chlorfenvinphos to levels below detection and unable to degrade atrazine, diuron and isoproturon. Penicillium citrinum, Aspergillus fumigatus, Aspergillus terreus and Trichoderma harzianum were found to be able to resist and degrade chlorfenvinphos. These fungi are therefore expected to play an important role in the degradation of this and other pollutants present in the aquatic environment.