Journal of Microbiology

Research Support, Non-U.S. Gov't

In Vivo Studies with a Candida tropicalis Isolate Exhibiting Paradoxical Growth In Vitro in the Presence of High Concentration of Caspofungin: Sedigh Bayegan , Laszlo Majoros , Gabor Kardos , Adam Kemény-Beke , Cecilia Miszti , Renato Kovacs , Rudolf Gesztelyi; J. Microbiol. 2010;48(2):170-173. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-010-9221-y

Abstract: We investigated the activity of caspofungin against a Candida tropicalis clinical isolate showing paradoxical growth in vitro. BALB/c mice immunosuppressed by cyclophosphamide were infected intraperitoneally using 107 CFU/mouse. Caspofungin was administered intraperitoneally once daily for 5 days or as a single dose using the following doses: 0.12, 0.25, 1, 2, 3, 5, and 15 mg/kg. The single dose of caspofungin was effective only at 5 and 15 mg/kg concentrations (100% survival). Five-day caspofungin treatment led to 100% survival at doses of 1 mg/kg or higher. Caspofungin treatment significantly decreased the number of viable yeasts in the peritoneal lavage samples as well as in the infected abscesses at doses 1, 3, 5, and 15 mg/kg caspofungin as compared to the untreated control (P<0.001 in all cases), and even to the group treated with 0.12 mg/kg caspofungin (P<0.05 in all cases). At 2 mg/kg caspofungin dose, sterilization of the internal organs was reproducibly incomplete, suggesting that the role of paradoxical growth in the late clinical failure cannot be excluded.

Journal Article

Symbiotic Relationship between Microbacterium sp. SK0812 and Candida tropicalis SK090404: Seung Won Kang , Bo Young Jeon , Tae Sik Hwang , Doo Hyun Park; J. Microbiol. 2009;47(6):721-727. Published online February 4, 2010; DOI: https://doi.org/10.1007/s12275-009-0146-2

Abstract: A bacterium growing inside yeast cytoplasm was observed by light microscope without staining. The bacterium was separately stained from yeast cell by a fluorescent dye, 4′,6-diamidino-2-phenylindole (DAPI). The bacterium actively moved inside yeast cytoplasm and propagated in company with the yeast growth. The bacterium was separated from the yeast cytoplasm by selective disruption of yeast cells and the yeast without the intracellular bacterium (YWOB) was obtained by selective inactivation of bacterial cells. The yeast and the intracellular bacterium were identified as Candida tropicalis and Microbacterium sp., respectively. The length of Microbacterium sp. and C. tropicalis measured with SEM image was smaller than 0.5 μm and was larger than 5 μm, respectively. The yeast with the intracellular bacterium (YWIB) grew in a starch-based medium but the YWOB was not C. tropicalis has neither extracellular nor intracellular saccharification enzyme. Glucose was produced from starch by the extracellular crude enzyme (culture fluid) of Microbacterium sp. YWIB produced significantly more ethanol from glucose than YWOB but did not from starch. Conclusively, C. tropicalis is thought to catabolize starch dependent upon Microbacterium sp. growing in its cytoplasm and furnish stable habitat for the Microbacterium sp.

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