Detection in Orchards of Predominant Azole-Resistant Candida tropicalis Genotype Causing Human Candidemia, Taiwan.

Fluconazole-resistant clade 4 Candida tropicalis causing candidemia in humans has been detected in tropical/subtropical areas, including those in China, Singapore, and Australia. We analyzed 704 individual yeasts isolated from fruits, soil, water, and farmers at 80 orchards in Taiwan. The most common pathogenic yeast species among 251 isolates recovered from farmers were Candida albicans (14.7%) and C. parapsilosis (11.6%). In contrast, C. tropicalis (13.0%), C. palmioleophila (6.6%), and Pichia kudriavzevii (6.0%) were prevalent among 453 environmental isolates. Approximately 18.6% (11/59) of C. tropicalis from the environment were resistant to fluconazole, and 81.8% (9/11) of those belonged to the clade 4 genotype. C. tropicalis susceptibility to fluconazole correlated with susceptibilities to the agricultural azole fungicides, difenoconazole, tebuconazole, and triadimenol. Tandem gene duplications of mutated ERG11 contributed to azole resistance. Agriculture environments are a reservoir for azole-resistant C. tropicalis; discontinuing agricultural use of azoles might reduce emergence of azole-resistant Candida spp. strains in humans.

A booster dose of Delta × Omicron hybrid mRNA vaccine produced broadly neutralizing antibody against Omicron and other SARS-CoV-2 variants.

BACKGROUND: With the continuous emergence of new SARS-CoV-2 variants that feature increased transmission and immune escape, there is an urgent demand for a better vaccine design that will provide broader neutralizing efficacy. METHODS: We report an mRNA-based vaccine using an engineered "hybrid" receptor binding domain (RBD) that contains all 16 point-mutations shown in the currently prevailing Omicron and Delta variants. RESULTS: A booster dose of hybrid vaccine in mice previously immunized with wild-type RBD vaccine induced high titers of broadly neutralizing antibodies against all tested SARS-CoV-2 variants of concern (VOCs). In naïve mice, hybrid vaccine generated strong Omicron-specific neutralizing antibodies as well as low but significant titers against other VOCs. Hybrid vaccine also elicited CD8+/IFN-γ+ T cell responses against a conserved T cell epitope present in wild type and all VOCs. CONCLUSIONS: These results demonstrate that inclusion of different antigenic mutations from various SARS-CoV-2 variants is a feasible approach to develop cross-protective vaccines.

Mixed yeast infections in Taiwan.

Clinically significant yeast isolates were collected via Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) in 2014, and mixed infections were investigated. Among 44 out of 1092 specimens containing multiple species, 17, 11, 5, 3, and 8 were from urine, sputum, blood, ascites, and 6 others, respectively. There predominant combinations of mixed infection were 14 Candida albicans/Candida glabrata, 13 C. albicans/Candida tropicalis, and 9 C. glabrata/C. tropicalis. Furthermore, we also detected fluconazole resistant isolates Candida norvegensis and Candida krusei. Hence, it is important to accurately identify the species with different drug susceptibilities when they are in the same specimen.

The survey of tinea capitis and scalp dermatophyte carriage in nursing home residents.

Tinea capitis is a contagious dermatophyte infection of scalp and associated hairs. On the other hand, asymptomatic carriage is a status of positive dermatophyte scalp culture, but without signs or symptoms of tinea capitis, and no evidence of hair shaft invasion confirmed by direct microscopy. Tinea capitis and asymptomatic carriage mostly occur in children, but adult females are becoming another population in recent decades. In this study, we focused on the prevalence and related fungi of tinea capitis and asymptomatic carriage in elderly by the shampoo brush method, as well as the source of transmission, in 10 nursing home residents. Two hundred and thirteen residents were screened, and 186 isolates were identified, of which only three were dermatophytes (1.4%). The scalp dermatophyte isolates were identified as Trichophyton rubrum by morphological characters and sequences comparisons in all three cases. After revisiting, these cases were proved to be asymptomatic carriers by negative microscopic and culture examination; however, two cases were found to have concurrent tinea pedis and onychomycosis, which were identified as T. rubrum and Trichophyton interdigitale. The source of the T. rubrum scalp carriage may come from tinea elsewhere on the body of the same subject or from other people in the same institute. Finding and treating the source of carriage, as well as treating scalp carriage patients according to the colony counts, may help prevent disease spreading.

Yeast oropharyngeal colonization in human immunodeficiency virus-infected patients in central taiwan.

A prospective, cross-sectional study was conducted at a medical center in central Taiwan to understand the prevalence, associated factors, and microbiologic features for oropharyngeal yeast colonization in human immunodeficiency virus-infected outpatients. Oral yeast colonization was detected in 127 (45 %) patients, including 21 (16.5 %) colonized by more than one species. Of the 154 isolates, Candida albicans was the most common species (114, 74 %), followed by Candida dubliniensis (10, 6.5 %), Candida glabrata (10, 6.5 %), Candida tropicalis (7, 4.5 %), and 13 others. We found that receiving antituberculous drug (p = 0.046) or atazanavir (p = 0.045) was two predictors for patients colonized by non-C. albicans species (p = 0.005) and risking mixed yeast colonization (p = 0.009). Even though our data showed that clinical antifungal drugs remained effective in vitro against the colonizing yeasts, the increased mixed yeast colonization indicates a potential issue for controlling mixed infections in hospital settings.

Fruits are vehicles of drug-resistant pathogenic Candida tropicalis.

IMPORTANCE: Of 123 identified isolates from the fruit surface, C. tropicalis was the most frequently found species, followed by Meyerozyma caribbica and Candida krusei. All three fluconazole-resistant C. tropicalis were non-susceptible to voriconazole and belonged to the same predominant genotype of azole-resistant C. tropicalis causing candidemia in patients in Taiwan. Our findings provide evidence that fruit should be washed before eaten not only to remove chemicals but also potential drug-resistant pathogenic microbes, especially for immunocompromised individuals. To keep precious treatment options in patients, we not only continuously implement antimicrobial stewardship in hospitals but also reducing/stopping the use of agricultural fungicide classes used in human medicine.

Distribution of Yeast Species and Risk Factors of Oral Colonization after Oral-Care Education among the Residents of Nursing Homes.

Most yeasts causing infections in humans are part of commensal microflora and etiological agents of different infections when hosts become susceptible, usually due to becoming immunocompromised. The colonization of potentially pathogenic microbes in the oral cavity is increased by poor oral hygiene. This follow-up survey was conducted approximately two months after providing information on proper oral care at 10 nursing homes in Taiwan. Among the 117 of 165 residents colonized by yeasts, 67 were colonized by more than one yeast species. A total of 231 isolates comprising eight fungal genera and 25 species were identified. Candida albicans (44.6%) was the dominant species, followed by Candida glabrata (17.7%), Candida parapsilosis (8.7%), Candida tropicalis (7.8%), and Candida pararugosa (7.3%). Residents having a yeast colony-forming unit >10 (OR, 8.897; 95% CI 2.972−26.634; p < 0.001) or using a wheelchair (OR, 4.682; 95% CI 1.599−13.705; p = 0.005) were more likely to be colonized by multiple species. By comparing before and after oral-care education, dry mouth (OR, 3.199; 95% CI 1.448−7.068; p = 0.011) and having heart disease (OR, 2.681; 95% CI 1.068−6.732; p = 0.036) emerged as two independent risk factors for increased density of colonizing yeast.

The Use of MALDI-TOF Mass Spectrometry to Analyze Commensal Oral Yeasts in Nursing Home Residents.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method to identify microorganisms in clinical laboratories. This study isolates yeast-like microorganisms in the oral washes that are collected from non-bedridden nursing home residents, using CHROMagar Candida plates, and identifies them using Bruker MALDI-TOF MS. The ribosomal DNA sequences of the isolates are then examined. Three hundred and twenty yeast isolates are isolated from the oral washes. Candida species form the majority (78.1%), followed by Trichosporon/Cutaneotrichosporon species (8.8%). Bruker MALDI-TOF MS gives a high-level confidence, with a log(score) value of ≥1.8, and identifies 96.9% of the isolates. There are six inconclusive results (1.9%), and those sequences are verified as rare clinical species, including Candida ethanolica, Cutaneotrichosporon jirovecii, Exophiala dermatitidis, and Fereydounia khargensis. Almost all of the isolates have a regular color on the CHROMagar Candida plates. If the colonies are grouped by color on the plates, a specific dominant yeast species is present in each color group, except for purple or orange isolates. In conclusion, MALDI-TOF MS is verified as a fast, accurate and practical method to analyze oral yeasts in elderly subjects.

Rep1p negatively regulating MDR1 efflux pump involved in drug resistance in Candida albicans.

Overexpression of MDR1 efflux pump is a major mechanism contributing to drug resistance in Candida albicans, the most common human fungal pathogen. To elucidate the regulatory pathway of drug resistance, we have identified a negative regulator of MDR1 and named it Regulator of Efflux Pump 1 (REP1). Overexpression of REP1 in Saccharomyces cerevisiae increased susceptibility to fluconazole. Furthermore, null mutations on REP1 decreased the susceptibility to antifungal drugs in C. albicans resulting from increased expression of MDR1 mRNA. Hence, Rep1p is involved in drug resistance by negatively regulating MDR1 in C. albicans.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus colonization among human immunodeficient virus-infected outpatients in Taiwan: oral Candida colonization as a comparator.

Human immuodeficency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have increased in recent years in Taiwan. This study was undertaken to determine the prevalence of and risk factors for nasal and oral S. aureus and MRSA colonization among contemporary HIV-infected populations. Clinical variables for S. aureus and MRSA colonization among HIV-infected outpatients from three hospitals were analyzed and compared with those for oral Candida colonization. Genetic characteristics of MRSA isolates were analyzed. A total of 714 patients were screened for nasal S. aureus colonization, and a subset of 457 patients were also screened for oral S. aureus colonization. Of all patients, 79.4% were receiving HAART, and their mean CD4 count was 472 cells/mm3. The colonization rates in the oral cavity, nasal cavity, and at either site were 18.8%, 31.7%, and 36.8%, respectively, for S. aureus, and 3.1%, 4.4%, and 5.5%, respectively, for MRSA. These rates were all much lower than the previously reported rate of oral Candida colonization (52.4%). By multivariate analysis, a suppressed viral load (<200 copies/mL) protected against oral S. aureus, MRSA, and Candida colonization, and recent use of antibacterial agents protected against oral and nasal S. aureus colonization. Recent incarceration increased the risk of nasal MRSA colonization, while recent hospitalization, tuberculosis, older age, and intravenous drug use increased the risk of oral Candida colonization. Candida spp. did not augment S. aureus or MRSA colonization in the oral cavity. Most of the 41 MRSA isolates recovered belonged to the SCCmec IV/pvl-negative (51.2%) and VT/pvl-positive (26.8%) ST59 local prevalent CA-MRSA clones. Distinct carriage rates demonstrated here suggested that mucosal immunity against colonization might differ in terms of microbes and sites. A decreased risk in oral carriage of MRSA and Candida might be a benefit of HAART.

The distribution and drug susceptibilities of clinical Candida species in TSARY 2014.

The species distribution and drug susceptibilities of 1106 Candida isolates collected in Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) in 2014 were determined. Candida albicans is still the dominant species, accounting for 35.9%, followed by 28.3% C. glabrata, 26.6% C. tropicalis, 5.2% C. parapsilosis, 1.0% C. krusei, and 3.0% of 13 other species. Interestingly, the prevalence of candidemia caused by C. glabrata in the present study is significantly higher than that in previous three surveys (39/220 vs. 54/471, P=0.025). We found that 31 (2.8%), 24 (2.2%), 1 (0.09%), and 0 isolates were resistant to fluconazole, voriconazole, anidulafungin, and amphotericin B, respectively. There is a significant increase in fluconazole (P=0.00002) and voriconazole (P=0.00006) resistant rates when compared to the isolates collected in 2010. Importantly, all the 24 voriconazole resistant isolates identified were also resistant to fluconazole. Hence, cross-resistance among azole-type drugs is an emerging issue for managing fungal infections.

Action of solamargine on human lung cancer cells--enhancement of the susceptibility of cancer cells to TNFs.

Solamargine (SM), isolated from Solanum incanum herb, displayed a superior cytotoxicity in four human lung cancer cell lines. The half-inhibitory concentrations (IC50), of the cell viability assay for H441, H520, H661 and H69 cells were 3, 6.7, 7.2 and 5.8 microM, respectively. SM-induced apoptosis of these cells by PS externalization in a dose-dependent manner and increased sub-G1 fraction were observed. Quenching of the expression of tumor necrosis factor receptors (TNFRs) during the progress of human lung carcinogenesis has been previously reported. SM may induce cell apoptosis via modulating the expression of TNFRs and their subsequent TRADD/FADD signal cascades. Subsequently, SM treatment increased the binding activities of TNF-alpha and TNF-beta to the lung cancers, and the intrinsic TNFs-resistant cancer cells became susceptible to TNF-alpha and -beta. In addition, SM caused release of cytochrome c, downregulation of anti-apoptotic Bcl-2 and Bcl-xL, increase of caspase-3 activity, and DNA fragmentation. Thus, SM could modulate the expressions of TNFRs and Bcl-2, and might be a potential anticancer agent for TNFs and Bcl-2 related resistance of human lung cancer cells.

An emerging issue of mixed yeast cultures.

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.

Species distribution and drug susceptibilities of Candida isolates in TSARY 2010.

Susceptibilities to antifungal drugs of 1083 Candida isolates collected in Taiwan Surveillance of Antimicrobial Resistance of Yeasts in 2010 were determined. There were 422 (39%) C. albicans, 270 (24.9%) C. tropicalis, 258 (23.8%) C. glabrata, 87 (8%) C. parapsilosis, 18 (1.7%) C. krusei, and 28 (2.6%) of 13 other species. In the present study, we have applied species-specific clinical breakpoints for common species and epidemiological cutoff values for rare species. We found that majority of isolates were susceptible to tested drugs. A total of 15, 3, 2, and 0 isolates were not susceptible to fluconazole, voriconazole, amphotericin B, and anidulafungin, respectively. We found that three of the four fluconazole non-susceptible C. albicans isolates were resistant to voriconazole. Hence, there is an issue of cross-resistance among azole-type drugs.

Predisposing factors for oropharyngeal colonization of yeasts in human immunodeficiency virus-infected patients: a prospective cross-sectional study.

BACKGROUND: Oropharyngeal candidiasis continues to be a major opportunistic infection in human immunodeficiency virus (HIV)-infected patients. The objectives of this study were to investigate the prevalence, associated factors, and microbiologic features for oropharyngeal yeast colonization in HIV-infected patients. METHODS: From October to December 2009, consecutive HIV-infected patients older than 18 years were recruited in this study. Demographic information, underlying conditions, and clinical histories were collected. Oropharyngeal swab cultures for yeasts and antifungal drug susceptibilities of the isolates were performed. RESULTS: Of the 105 HIV-infected patients, 54 (51.4%) were colonized with yeasts, including 11 patients (20.4%) with more than one species. Among the 68 isolates, Candida albicans accounted for 73.5%, followed by Candida tropicalis (5.9%), Candida glabrata (5.9%), and Candida dubliniensis (4.4%). There were 7.5% and 6% Candida isolates resistant to fluconazole and voriconazole, respectively. All of the Candida isolates were susceptible to amphotericin B. A higher prevalence of yeast colonization was noted in patients with a CD4 cell count ≤200 cells/µL (p = 0.032). Multivariate regression analysis showed that intravenous drug use was an independent associated factor for oropharyngeal yeast colonization (odds ratio, 5.35; 95% confidence interval, 1.39-20.6; p = 0.015), as well as protease inhibitor-containing antiretroviral therapy (odds ratio, 3.59; 95% confidence interval, 1.41-9.12; p = 0.007). CONCLUSION: Despite previous studies showing that protease inhibitors decreased Candida adhesion to epithelial cells in vitro, the current study found protease inhibitor-containing antiretroviral therapy predisposed to oropharyngeal yeast colonization in HIV-infected patients.

Comparison of human and soil Candida tropicalis isolates with reduced susceptibility to fluconazole.

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.