Inadvertent Selection of a Pathogenic Fungus Highlights Areas of Concern in Human Clinical Practices

Area of Science:

• Clinical Microbiology
• Antimicrobial Resistance
• Healthcare-Associated Infections

Background:

• Emerging multidrug-resistant yeast pathogen *Candida auris* poses a significant threat in healthcare settings.
• Nosocomial pathogens like *Candida glabrata* are common in hospitals.
• Hospital cleaners are crucial for infection control but their impact on microbial populations is not fully understood.

Purpose of the Study:

• To investigate the development of tolerance to hospital cleaners (Oxivir®, CaviCide™) in *Candida auris* and *Candida glabrata*.
• To determine the competitive dynamics between *C. auris* and *C. glabrata* under disinfectant exposure.
• To assess whether clinical disinfection practices could inadvertently select for tolerant fungal pathogens.

Main Methods:

• Selection of cleaner-tolerant subpopulations of *C. auris* and *C. glabrata*.
• Purification of individual species from mixed cultures.
• Competition assays to evaluate dominance under disinfectant stress.
• Microbiological analyses to assess population dynamics.

Main Results:

• The common nosocomial pathogen *Candida glabrata* readily dominated mixed populations of *C. auris* and *C. glabrata* when exposed to hospital cleaners.
• A cleaner-tolerant subpopulation of *C. glabrata* was selected.
• Hospital cleaners preferentially selected for *C. glabrata* over *C. auris* in mixed cultures.

Conclusions:

• Exposure to common hospital cleaners can preferentially select for stress-tolerant fungal pathogens.
• Clinical disinfection practices may contribute to the selection and persistence of tolerant microbes in healthcare environments.
• Findings highlight the need to consider the ecological impact of disinfectants on microbial communities within hospitals.