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Dissemination of yeasts after gastrointestinal inoculation in antibiotic-treated mice
Abstract:
Mice pretreated with antibiotics were inoculated intragastrically with different yeast isolates to determine whether the resulting disruption of the normal flora ecology would allow certain fungi to colonize and disseminate from the gastrointestinal tract. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora, and predisposed mice to gastrointestinal overgrowth and subsequent dissemination by Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, and Torulopsis glabrata. A clinical isolate of Rhodotorula rubra, on the other hand, was unable to maintain a stable population in the gut of similar mice and could not be isolated from systemic organs. Control animals not receiving antibiotic therapy, challenged with C. albicans, showed significantly lower gut population levels of yeasts, and Candida organisms could not be grown from visceral organs. It is suggested that suppression of fungi within the gastrointestinal tract by members of the normal bacterial flora may be an important mechanism whereby fungi are confined to the alimentary tract.
Insights
Antibiotic disruption of gut bacteria allows fungi like Candida albicans to overgrow and spread. Normal gut flora suppresses fungi, preventing systemic infections.
Area of Science:
- Microbiology
- Mycology
- Gastroenterology
Background:
- The gastrointestinal tract harbors a complex microbial ecosystem.
- Fungal colonization and dissemination are significant clinical concerns, particularly in immunocompromised individuals.
Purpose of the Study:
- To investigate the role of indigenous gastrointestinal bacterial flora in controlling fungal colonization and dissemination.
- To determine if disruption of normal gut flora by antibiotics predisposes to fungal overgrowth and systemic spread.
Main Methods:
- Mice were pretreated with antibiotics to alter gut microbiota.
- Inoculation with various yeast isolates (Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, Torulopsis glabrata, Rhodotorula rubra) was performed intragastrically.
- Fungal populations in the gastrointestinal tract and systemic organs were quantified.
Main Results:
- Antibiotic pretreatment led to decreased indigenous bacterial flora and predisposed mice to gastrointestinal overgrowth and dissemination of several Candida species and Torulopsis glabrata.
- Rhodotorula rubra failed to establish a stable gut population or disseminate systemically.
- Control mice without antibiotic treatment showed lower yeast gut populations, and Candida was not isolated from systemic organs.
Conclusions:
- Suppression of gastrointestinal fungi by normal bacterial flora is a crucial mechanism for confining fungi to the alimentary tract.
- Disruption of the gut microbiota significantly increases the risk of fungal overgrowth and systemic dissemination.