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[Identification and susceptibility of clinically isolated yeast-like fungi]
Abstract:
We studied the identification and susceptibility of clinically isolated yeast-like fungi at Showa University Hospital from April 1988 to March 1989. Clinically significant of yeast-like fungi were observed in 7.1% of specimens from outpatients, 13.0% of inpatients. In both outpatients and inpatients, yeast-like fungi were isolated mainly from sputum and urine. But, one third of them were considered as non-pathogenic and not identified. The species of isolates were, Candida albicans 57%, Candida tropicalis 14% and Candida glabrata 8% in both inpatients and outpatients, and these species shared most part. The isolation frequency of Candida parapsilosis was higher in blood and cerebrospinal fluid (CSF) specimen than the others. The susceptibility test by agar dilution method indicated most of the isolates were susceptible to Amphotericin B and Miconazole (MIC less than or equal to 25 micrograms/ml). There was no difference in MIC between predominantly isolated fungi and commonly isolated fungi. Notably, isolates from blood and CSF showed a significant high tolerance against Amphotericin B and Miconazole than from the other specimens. The MICs of Fluconazole were shown to be very high (greater than 100 micrograms/ml) in normal Sabouraud agar, were decreased dose-dependently by human sera in the medium. These findings indicated the component(s) of sera enhanced the anti-fungal activity of Fluconazole.
Insights
This study identified common yeast-like fungi in clinical specimens, finding Candida albicans most prevalent. Most isolates were susceptible to Amphotericin B and Miconazole, though blood and CSF isolates showed higher tolerance.
Area of Science:
- Medical Mycology
- Clinical Microbiology
- Antimicrobial Susceptibility Testing
Background:
- Yeast-like fungi are significant pathogens in hospital settings.
- Understanding the prevalence and susceptibility patterns of these fungi is crucial for effective treatment.
- Previous studies have highlighted variations in fungal isolation rates and resistance.
Purpose of the Study:
- To identify and determine the antifungal susceptibility of clinically isolated yeast-like fungi.
- To analyze the distribution of fungal species in different clinical specimens.
- To evaluate the impact of human serum on antifungal drug efficacy.
Main Methods:
- Prospective study of yeast-like fungi isolated from clinical specimens at Showa University Hospital (April 1988–March 1989).
- Identification of fungal isolates.
- Antifungal susceptibility testing using the agar dilution method for Amphotericin B, Miconazole, and Fluconazole.
- Evaluation of the effect of human serum on Fluconazole minimum inhibitory concentrations (MICs).
Main Results:
- Yeast-like fungi were isolated from 7.1% of outpatient and 13.0% of inpatient specimens, primarily from sputum and urine.
- Candida albicans (57%), Candida tropicalis (14%), and Candida glabrata (8%) were the most common species.
- Most isolates were susceptible to Amphotericin B and Miconazole (MIC ≤ 25 µg/ml), but isolates from blood and cerebrospinal fluid (CSF) exhibited higher tolerance.
- Fluconazole MICs were high (>100 µg/ml) on standard agar but decreased dose-dependently in the presence of human serum.
Conclusions:
- Candida species are the predominant yeast-like fungi encountered in clinical settings.
- While generally susceptible to Amphotericin B and Miconazole, specific isolates (e.g., from blood/CSF) may show increased tolerance.
- Human serum components significantly enhance the in vitro activity of Fluconazole against yeast-like fungi.