Browsing by Author "Chang, Te-Pin"

Now showing 1 - 4 of 4

An emerging issue of mixed yeast cultures
(2014-08-01)
Yang, Yun-Liang
;
Chu, Wen-Li
;
Lin, Chih-Chao
;
Tsai, Sheng-Hua
;
Chang, Te-Pin
Background: Different yeast species have different susceptibilities to commonly prescribed antifungal drugs. Thus, it is important to accurately determine the species of pathogenic yeasts, especially when more than one species are in a specimen. Methods: Clinically significant yeast isolates were collected via the Taiwan Surveillance of Antimicrobial Resistance of Yeasts from July to September in 2010. The identifications of isolates were assessed in the core laboratory at the National Health Research Institutes. Results: Of the 1127 isolates recovered, 1088 were of Candida genus, accounting for 96.53% of the total isolates, followed by Cryptococcus (15, 1.33%), Trichosporon (12, 1.06%), Kodamaea (4, 0.35%), Pichia (4, 0.35%), and three others. In all, 38 out of 1116 (3.4%) specimens had mixed yeast cultures. One ascites specimen had three species, Candida albicans, Candida glabrata, and Candida tropicalis. In the remaining 37 specimens, 16 had a combination of C. albicans and C. glabrata, eight C. albicans and C. tropicalis, five C. glabrata and C. tropicalis, three Candida krusei and C. tropicalis, and five with different combinations. Conclusion: The high prevalence of cultures with mixed yeasts may be an emerging issue. Thus, to determine mixed yeast cultures in the same specimen, we highly recommend CHROMagar Candida medium to culture yeast isolates directly from the specimen. Copyright (C) 2013, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. All rights reserved.
Comparison of Human and Soil Candida tropicalis Isolates with Reduced Susceptibility to Fluconazole
(2012-04-05)
Yang, Yun-Liang
;
Lin, Chih-Chao
;
Chang, Te-Pin
;
Lauderdale, Tsai-Ling
;
Chen, Hui-Ting
Infections caused by treatment-resistant non-albicans Candida species, such as C. tropicalis, has increased, which is an emerging challenge in the management of fungal infections. Genetically related diploid sequence type (DST) strains of C. tropicalis exhibiting reduced susceptibility to fluconazole circulated widely in Taiwan. To identify the potential source of these wildly distributed DST strains, we investigated the possibility of the presence in soil of such C. tropicalis strains by pulsed field gel electrophoresis (PFGE) and DST typing methods. A total of 56 C. tropicalis isolates were recovered from 26 out of 477 soil samples. Among the 18 isolates with reduced susceptibility to fluconazole, 9 belonged to DST149 and 3 belonged to DST140. Both DSTs have been recovered from our previous studies on clinical isolates from the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) program. Furthermore, these isolates were more resistant to agricultural azoles. We have found genetically related C. tropicalis exhibiting reduced susceptibility to fluconazole from the human hosts and environmental samples. Therefore, to prevent patients from acquiring C. tropicalis with reduced susceptibility to azoles, prudent use of azoles in both clinical and agricultural settings is advocated.
Distribution and drug susceptibilities of Candida species causing candidemia from a medical center in central Taiwan
(2013-12-01)
Chang, Te-Pin
;
Ho, Mao-Wang
;
Yang, Yun-Liang
;
Lo, Pai-Chang
;
Lin, Pei-Sheng
Invasive fungal infections have increased significantly in the past few decades because of the increase in high-risk populations. To investigate the distribution and drug susceptibilities of such infections, we analyzed all 152 Candida isolates causing candidemia from 2004 to 2006 at the China Medical University Hospital, a medical center in central Taiwan. Candida albicans was the most common species, accounting for 52.6 % of the isolates, followed by C. tropicalis (19.7 %), C. parapsilosis (14.5 %), C. glabrata (8.6 %), C. guilliermondii (3.9 %), and C. pelliculosa (0.7 %). All isolates were susceptible to amphotericin B, anidulafungin, micafungin, and voriconazole according to minimum inhibitory concentrations (MICs) after a 24-h incubation; 0.7 %, 6.6 %, and 7.9 % of isolates were resistant to amphotericin B, fluconazole, and voriconazole, respectively, after 48-h incubation. Both C. albicans and C. parapsilosis had high degrees of agreement for azoles between 24- and 48-h incubation periods, whereas C. glabrata (38.5-46.2 %) and C. tropicalis (56.7-63.3 %) did not. The majority of the isolates with high azole MICs displayed a trailing growth phenotype. Hence, the MICs of different drugs after 24-h incubation may be considered for prognosis of candidemia.
Loss of Heterozygosity of FCY2 Leading to the Development of Flucytosine Resistance in Candida tropicalis
(2011-06-01)
Chen, Yen-Ning
;
Lo, Hsiu-Jung
;
Wu, Chia-Chen
;
Ko, Hui-Ching
;
Chang, Te-Pin
As fluconazole resistance becomes an emerging issue for treating infections caused by Candida tropicalis, searching for alternative becomes a prominent task. In the present study, 97 clinical isolates of C. tropicalis were tested for the susceptibilities to flucytosine (5FC) with the Etest method. Although only one isolate was resistant to 5FC, 30 susceptible isolates could produce resistant progeny after exposure to the drug. Interestingly, 22 of these 30 clinical isolates had a heterozygous G/T at the 145th position on FCY2, encoding purine-cytosine permease, whereas their progeny recovered from within the inhibitory ellipses had homozygous T/T, resulting in null alleles for both copies of the gene and produced only truncated proteins, effecting the 5FC resistance. Furthermore, we found that two major fluconazole-resistant clinical clones, diploid sequence type 98 (DST98) and DST140, had a homozygous G/G at the 145th position, and neither was able to produce 5FC-resistant progeny within the inhibitory ellipses. Hence, strains of C. tropicalis containing heterozygous alleles may develop 5FC resistance readily, whereas those with homozygous G/G wild-type alleles can be treated with 5FC. Subsequently, a combination of 5FC and another antifungal drug is applicable for treating infections of C. tropicalis.