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Updated: May 24, 2025
Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
Potable water as a source of intermediate and borderline-resistant Aspergillus and Candida strains
Monika Novak Babič1, Nina Gunde-Cimerman2
1Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Ljubljana SI-1000, Slovenia
Abstract:
The World Health Organization calls to assess possible health risks from emerging fungi originating not only from hospitals but also from the natural environment. Fungal contamination in oligotrophic water systems represents a public health concern due to the potential for the emergence of antifungal-resistant strains. This study focused on the identification of Aspergillus spp. and Candida spp. isolated from different water sources and materials in contact with water. Isolated strains have been tested against nine antifungals to assess the prevalence of resistance in these strains. Only one strain of Aspergillus protuberus was resistant to amphotericin B. On the other hand, all Candida strains were intermediately resistant to anidulafungin and micafungin, 5.8% were borderline resistant to 5-flucytosine and fluconazole, and 3% to voriconazole. Candida parapsilosis sensu stricto isolated from water samples had statistically higher minimal inhibitory concentration (MIC) for anidulafungin than clinical strains and clinical strains had statistically higher MIC for itraconazole. Statistical analysis pointed out habitat to be significant for higher MIC in C. parapsilosis. Our findings show that borderline-resistant strains can be transferred by water; thus, potable water should be considered as a possible source of resistant strains in hospitals and healthcare units.
Insights
Emerging antifungal-resistant fungi, like Candida, are found in water systems. This study highlights potable water as a potential source for transmitting resistant strains to healthcare settings.
Area of Science:
- Environmental microbiology
- Public health
- Antimicrobial resistance
Background:
- The World Health Organization emphasizes assessing health risks from emerging fungi in both natural and hospital environments.
- Fungal contamination in oligotrophic water systems is a growing public health concern due to the rise of antifungal resistance.
Purpose of the Study:
- To identify Aspergillus and Candida species in various water sources and materials.
- To determine the prevalence of antifungal resistance in these isolated fungal strains.
Main Methods:
- Isolation and identification of Aspergillus and Candida species from water samples and associated materials.
- Antifungal susceptibility testing against nine different antifungal agents.
- Statistical analysis comparing minimal inhibitory concentrations (MICs) between environmental and clinical strains of Candida parapsilosis.
Main Results:
- One Aspergillus protuberus strain showed resistance to amphotericin B.
- All Candida strains exhibited intermediate resistance to anidulafungin and micafungin.
- 5.8% of Candida strains were borderline resistant to 5-flucytosine and fluconazole, and 3% to voriconazole.
- Candida parapsilosis from water had higher anidulafungin MICs than clinical strains; clinical strains had higher itraconazole MICs.
Conclusions:
- Potable water can transfer borderline-resistant fungal strains.
- Water systems, including potable water, should be recognized as potential reservoirs for antifungal-resistant fungi, posing a risk to hospitals and healthcare facilities.
