Candida rugosa, an emerging fungal pathogen with resistance to azoles: geographic and temporal trends from the ARTEMIS DISK antifungal surveillance program

Gastrointestinal colonization by Diutina (Candida) rugosa in a 6-year-old Siberian Husky

A 6-year-old 21.5 kg castrated male Siberian Husky was presented for acute onset of lethargy, vomiting, hemorrhagic diarrhea, and inappetence. Physical examination revealed marked discomfort upon abdominal palpation and 5%-7% dehydration. The CBC and biochemical profile revealed changes consistent with mild to moderate inflammation, dehydration, and gastrointestinal (GI) disease. Despite aggressive gastrointestinal support, anorexia persisted, and an upper GI endoscopy was performed in conjunction with esophagostomy tube placement. Endoscopy revealed abnormal gastric mucosa characterized by moderately well-demarcated areas of blue-black discoloration. Impression smears of a gastric biopsy revealed abundant extracellular yeasts with morphology most consistent with Candida spp. and frequent extracellular cocci. Similar yeast and bacteria, in lower numbers, were observed on cytologic analysis of a direct smear of the rectal mucosa. A rectal swab submitted for fungal culture yielded pure growth of fungal yeasts identified as Diutina (formerly Candida) rugosa by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry. The dog's clinical signs improved with fluconazole, and he was discharged. Follow-up fungal culture of a rectal swab showed no growth of D. rugosa. To the authors' knowledge, this is the first case report that describes the clinical, hematologic, cytologic, and gross findings of enteric colonization by D. rugosa in a dog.

Thymol-Modified Oleic and Linoleic Acids Encapsulated in Polymeric Nanoparticles: Enhanced Bioactivity, Stability, and Biomedical Potential

Unsaturated fatty acids, such as oleic acid (OA) and linoleic acid (LA), are promising antimicrobial and cytostatic agents. We modified OA and LA with thymol (TOA and TLA, respectively) to expand their bioavailability, stability, and possible applications, and encapsulated these derivatives in polymeric nanoparticles (TOA-NPs and TLA-NPs, respectively). Prior to synthesis, we performed mathematical simulations with PASS and ADMETlab 2.0 to predict the biological activity and pharmacokinetics of TOA and TLA. TOA and TLA were synthesized via esterification in the presence of catalysts. Next, we formulated nanoparticles using the single-emulsion solvent evaporation technique. We applied dynamic light scattering, Uv-vis spectroscopy, release studies under gastrointestinal (pH 1.2-6.8) and blood environment simulation conditions (pH 7.4), and in vitro biological activity testing to characterize the nanoparticles. PASS revealed that TOA and TLA have antimicrobial and anticancer therapeutic potential. ADMETlab 2.0 provided a rationale for TOA and TLA encapsulation. The nanoparticles had an average size of 212-227 nm, with a high encapsulation efficiency (71-93%), and released TOA and TLA in a gradual and prolonged mode. TLA-NPs possessed higher antibacterial activity against B. cereus and S. aureus and pronounced cytotoxic activity against MCF-7, K562, and A549 cell lines compared to TOA-NPs. Our findings expand the biomedical application of fatty acids and provide a basis for further in vivo evaluation of designed derivatives and formulations.

Meyerozyma guilliermondii species complex: review of current epidemiology, antifungal resistance, and mechanisms

Meyerozyma guilliermondii has been accepted as a complex composed of Meyerozyma guilliermondii, Meyerozyma carpophila, and Meyerozyma caribbica. M. guilliermondii is a saprophyte detected on human mucosa and skin. It can lead to serious infections in patients with risk factors like chemotherapy, immunodeficiency, gastrointestinal or cardiovascular surgery, and oncology disorders. Most deaths related to M. guilliermondii infections occur in individuals with malignancy. In recent decades, incidence of M. guilliermondii infections is increased. Sensitivity of this microorganism to conventional antifungals (e.g., amphotericin B, fluconazole, micafungin and anidulafungin) was reduced. Prophylactic and empirical uses of these drugs are linked to elevated minimal inhibitory concentrations (MICs) of M. guilliermondii. Drug resistance has concerned many researchers across the world. They are attempting to discover appropriate solution to combat this challenge. This study reviews the most important mechanisms of resistance to antifungals developed by in M. guilliermondii species complex.

Isolation Frequency of Fluconazole-Resistant Candida Species From Cockroaches: A Cross-Sectional Study From a National Hospital in Dar es Salaam, Tanzania

Background: Cockroaches are common pests in homes and hospitals. They cause allergic reactions in some individuals and are potential vectors for various infectious pathogens. The study investigated the extent to which hospital cockroaches act as vectors and reservoirs of medically important fungal pathogens on their external surfaces.

Methods: Cockroaches were captured from the selected hospital locations including the burn unit, adult surgical wards, pediatric oncology wards, intern hostel kitchen, and the central kitchen of a national referral teaching hospital in Tanzania. Normal saline washings from the external surface of cockroaches were cultured on standard mycological media to facilitate isolation and identification of medically important molds and yeasts. The susceptibility of Candida species isolates to fluconazole was tested using the Clinical and Laboratory Standards Institute (CLSI) M27-A3 microdilution method.

Results: A total of 69 cockroaches were captured from various hospital sites between February and April 2017. All cockroaches captured were shown to carry medically important fungi. A total of 956 medically important fungi were isolated; 554 (57.9%) were of Candida species, 222 (23.2%) were of Aspergillus species, 30 (3.1%) were of​​​​​​​ Cladosporium species, 17 (1.8%) were of​​​​​​​ Rhizopus species, 11 (1.2%) were of​​​​​​​ Geotrichum species, nine (0.9%) were of​​​​​​​ Penicillium species, seven (0.7%) were of​​​​​​​ Alternaria species, six (0.6%) were of​​​​​​​ Fusarium species, three (0.3%) were of​​​​​​​ Mucor species, and 97 (10.1%) were of other species. Of the Aspergillus species, Aspergillus fumigatus (111, 50.0%) was the most commonly isolated, followed by Aspergillus niger (35, 15.8%) among the Aspergillus isolates. Out of the 103 selected isolates, 18 (17.5%) of the Candida isolates normally not intrinsically resistant to fluconazole demonstrated resistance to this drug. Resistance was most frequently found in Candida parapsilosis (3, 30%), Candida pseudotropicalis (10, 23.8%), and Candida glabrata (2, 18.2%). The isolates with the least proportion of resistance to fluconazole were Candida albicans (2, 6.3%).

Conclusion: Cockroaches from this hospital may act as reservoirs of medically important opportunistic fungi exhibiting resistance to fluconazole.

Marked virulence and azole resistance in Candida albicans isolated from patients with periodontal disease

Candida albicans is an opportunistic fungus frequently associated with periodontal diseases. The objective of this study was to determine the expression patterns of virulence genes associated with those of azole resistance among the strains of C. albicans isolated from patients with periodontal disease. We isolated 80 strains of C. albicans from patients with periodontal disease enrolled from two dental clinics and their antifungal susceptibilities were evaluated using the disc diffusion method. C. albicans and its virulence genes were identified using PCR. The expressions of the virulence genes of C. albicans were analyzed using real-time PCR post in vitro infection of the cell line A549. The phenotype for resistance against azoles such as ketoconazole and fluconazole was observed in all analyzed strains (n = 80), which coincided with the high frequency of occurrence of the genes CDR1 and MDR1 associated with resistance. The frequencies of detection and expression of the genes HWP1 (47/15), ALS1 (80/66), ALS3 (70/30), LIP1 (78/44), LIP4 (77/65), LIP5 (79/58), LIP6 (79/58), PLB1 (79/65), and PLB2 (80/66) were found to be higher in the strains of C. albicans isolated from patients with moderate periodontitis and different expression patterns associated with those for azole resistance were identified. It could be elucidated that the high expression of virulence markers associated with azole resistance in C. albicans might be contributing to the chronicity of periodontal infections.

New and Promising Chemotherapeutics for Emerging Infections Involving Drug-resistant Non-albicans Candida Species

Fungal infections are a veritable public health problem worldwide. The increasing number of patient populations at risk (e.g. transplanted individuals, cancer patients, and HIV-infected people), as well as the use of antifungal agents for prophylaxis in medicine, have favored the emergence of previously rare or newly identified fungal species. Indeed, novel antifungal resistance patterns have been observed, including environmental sources and the emergence of simultaneous resistance to different antifungal classes, especially in Candida spp., which are known for the multidrug-resistance (MDR) profile. In order to circumvent this alarming scenario, the international researchers' community is engaged in discovering new, potent, and promising compounds to be used in a near future to treat resistant fungal infections in hospital settings on a global scale. In this context, many compounds with antifungal action from both natural and synthetic sources are currently under clinical development, including those that target either ergosterol or β(1,3)-D-glucan, presenting clear evidence of pharmacologic/pharmacokinetic advantages over currently available drugs against these two well-known fungal target structures. Among these are the tetrazoles VT-1129, VT-1161, and VT-1598, the echinocandin CD101, and the glucan synthase inhibitor SCY-078. In this review, we compiled the most recent antifungal compounds that are currently in clinical trials of development and described the potential outcomes against emerging and rare Candida species, with a focus on C. auris, C. dubliniensis, C. glabrata, C. guilliermondii, C. haemulonii, and C. rugosa. In addition to possibly overcoming the limitations of currently available antifungals, new investigational chemical agents that can enhance the classic antifungal activity, thereby reversing previously resistant phenotypes, were also highlighted. While novel and increasingly MDR non-albicans Candida species continue to emerge worldwide, novel strategies for rapid identification and treatment are needed to combat these life-threatening opportunistic fungal infections.

Necessity to identify candida species accurately with minimum inhibitory concentration determination in each case of bloodstream infections

BACKGROUND

Bloodstream Candida infection is a life-threatening event among ICU admitted patients. This infection is caused by a diverse range of Candida species having varied minimum inhibitory concentrations.

OBJECTIVES

To identify Candida species causing bloodstream infections with their antifungal susceptibility determination.

METHODS

Candida species isolated from the blood of ICU admitted patients were identified by phenotypic as well as by molecular methods including PCR-RFLP using MspI restriction enzyme and MALDI TOF MS. The minimum inhibitory concentration of fluconazole, voriconazole, amphotericin B and caspofungin was determined against isolated Candida species by CLSI M27A₃ guidelines.

RESULTS

A total of 119 Candida species were isolated. Among them, C. tropicalis(n=29) was the predominant isolate followed by C. parapsilosis(n=18), C. glabrata (n=12), C. krusei (n=11) and C. albicans(n=11). Uncommon Candida species isolated were; Wickerhamomyces anomalus(n=15), Kodaemia ohmeri(n=8), C. lusitaniae (n=5) and C. auris (n=2). A varied antifungal MIC values were observed. Caspofungin had the lowest MIC among the tested antifungals. Increased fluconazole MIC was observed against the isolated Candida species including C. tropicalis. All the isolated C. lusitaniae and C. auris strains have ≥1mcg/ml amphotericin B MIC. In comparison to fluconazole, voriconazole was more effective when tested in vitro.

CONCLUSION

Emergence of uncommon Candida species having varied antifungal MIC warns the physicians to have a prompt, accurate identification with antifungal MIC determination in each case of bloodstream Candida infections.

Genome Assemblies of Two Rare Opportunistic Yeast Pathogens: Diutina rugosa (syn. Candida rugosa) and Trichomonascus ciferrii (syn. Candida ciferrii)

Infections caused by opportunistic yeast pathogens have increased over the last years. These infections can be originated by a large number of diverse yeast species of varying incidence, and with distinct clinically relevant phenotypic traits, such as different susceptibility profiles to antifungal drugs, which challenge diagnosis and treatment. Diutina rugosa (syn. Candida rugosa) and Trichomonascus ciferrii (syn. Candida ciferrii) are two opportunistic rare yeast pathogens, which low incidence (< 1%) limits available clinical experience. Furthermore, these yeasts have elevated Minimum Inhibitory Concentration (MIC) levels to at least one class of antifungal agents. This makes it more difficult to manage their infections, and thus they are associated with high rates of mortality and clinical failure. With the aim of improving our knowledge on these opportunistic pathogens, we assembled and annotated their genomes. A phylogenomics approach revealed that genes specifically duplicated in each of the two species are often involved in transmembrane transport activities. These genomes and the reconstructed complete catalog of gene phylogenies and homology relationships constitute useful resources for future studies on these pathogens.

Dual DNA Barcoding for the Molecular Identification of the Agents of Invasive Fungal Infections

Invasive fungal infections, such as aspergillosis, candidiasis, and cryptococcosis, have significantly increased among immunocompromised people. To tackle these infections the first and most decisive step is the accurate identification of the causal pathogen. Routine identification of invasive fungal infections has progressed away from culture-dependent methods toward molecular techniques, including DNA barcoding, a highly efficient and widely used diagnostic technique. Fungal DNA barcoding previously relied on a single barcoding region, the internal transcribed spacer (ITS) region. However, this allowed only for 75% of all fungi to be correctly identified. As such, the translational elongation factor 1α (TEF1α) was recently introduced as the secondary barcode region to close the gap. Both loci together form the dual fungal DNA barcoding scheme. As a result, the ISHAM Barcoding Database has been expanded to include sequences for both barcoding regions to enable practical implementation of the dual barcoding scheme into clinical practice. The present study investigates the impact of the secondary barcode on the identification of clinically important fungal taxa, that have been demonstrated to cause severe invasive disease. Analysis of the barcoding regions was performed using barcoding gap analysis based on the genetic distances generated with the Kimura 2-parameter model. The secondary barcode demonstrated an improvement in identification for all taxa that were unidentifiable with the primary barcode, and when combined with the primary barcode ensured accurate identification for all taxa analyzed, making DNA barcoding an important, efficient and reliable addition to the diagnostic toolset of invasive fungal infections.

Antifungal susceptibility profiles of rare ascomycetous yeasts

Objectives

To generate antifungal susceptibility patterns for Trichomonascus ciferrii (Candida ciferrii), Candida inconspicua (Torulopsis inconspicua) and Diutina rugosa species complex (Candida rugosa species complex), and to provide key parameters such as MIC50, MIC90 and tentative epidemiological cut-off values (TECOFFs).

Methods

Our strain set included isolates of clinical origin: C. inconspicua (n = 168), D. rugosa species complex (n = 90) [Candida pararugosa (n = 60), D. rugosa (n = 26) and Candida mesorugosa (n = 4)], Pichia norvegensis (Candida norvegensis) (n = 15) and T. ciferrii (n = 8). Identification was performed by MALDI-TOF MS or internal transcribed spacer sequencing. Antifungal susceptibility patterns were generated for azoles, echinocandins and amphotericin B using commercial Etest and the EUCAST broth microdilution method v7.3.1. Essential agreement (EA) was calculated for Etest and EUCAST.

Results

C. inconspicua, C. pararugosa and P. norvegensis showed elevated azole MICs (MIC50 ≥0.06 mg/L), and D. rugosa and C. pararugosa elevated echinocandin MICs (MIC50 ≥0.06 mg/L). EA between methods was generally low (<90%); EA averaged 77.45%. TECOFFs were suggested for C. inconspicua and D. rugosa species complex.

Conclusions

Rare yeast species tested shared high fluconazole MICs. D. rugosa species complex displayed high echinocandin MICs, while C. inconspicua and P. norvegensis were found to have high azole MICs. Overall, the agreement between EUCAST and Etest was poor and therefore MIC values generated with Etest cannot be directly compared with EUCAST results.

Prevalence of Candida bloodstream isolates from patients in two hospitals in Vietnam

BACKGROUND AND OBJECTIVES

Identification of yeasts provides helpful information for appropriate administration of anti-fungal treatments; however, few reports from the Vietnam have been published. This study has been performed to find the prevalence of Candida blood stream isolates from patients in two hospitals in Vietnam.

MATERIALS AND METHODS

Candida spp. were isolated from blood cultures in two hospitals, Vietnam between May 2013 and May 2015. Participating hospitals were 103 Military Hospital, Ha Noi city (550 beds) and Cho Ray Hospital, Ho Chi Minh city (1800 beds). All the bloodstream isolates were identified to species level by the germ tube test and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, unknown isolates were subjected to PCR sequencing.

RESULTS

A total of 93 Candida isolates were isolated from blood cultures during the study period. The results of this study showed that C. tropicalis (n = 47, 50.54%) was the most common agent, followed by Candida albicans/dubliniensis (n = 18, 19.35%), C. parapsilosis (n = 16, 17.20%), C. glabrata (n = 6, 6.45%), C. mesorugosa (n = 5, 5.38%) and C. krusei (n = 1, 1.08%), respectively.

CONCLUSION

The frequency of the non-albicans Candida species in blood is increasing, especially C. tropicalis. Additional investigations should be made to clarify the epidemiological profile of invasive Candida bloodstream in Vietnam.

Development of Fungal Selective Amphiphilic Kanamycin: Cost-Effective Synthesis and Use of Fluorescent Analogs for Mode of Action Investigation

Amphiphilic aminoglycosides have attracted interest due to their novel antifungal activities. A crucial but often neglected factor for drug development in academia is cost of production. Herein is reported a one-step, inexpensive synthesis of amphiphilic alkyl kanamycins constituted with only natural components. The synthetic methodology also enabled the preparation of a series fluorescent amphiphilic aryl kanamycins for direct structure-activity mode of action studies. The lead compounds showed prominent antifungal activities against a panel of fungi, including Fusarium graminearum, Cryptococcus neoformans, and several Candida sp., and also significant antibacterial activities. With fluorescence-based whole cell assays, the aryl amphiphilic kanamycins were observed to permeabilize fungal surface membranes at faster rates than bacterial surface membranes. Also, the antifungal action of the amphiphilic kanamycins was observed to occur in a biphasic mode with an initial fast phase correlated with rapid membrane permeabilization at subminimal inhibitory concentrations and a slower phase membrane permeabilization that elevates the reactive oxygen species production leading to cell death. Inactive hydrophobic amphiphilic kanamycins displayed no membrane permeabilization. The results offer cost-effective methods for producing amphiphilic kanamycins and reveal insights into how nonfungal specific amphiphilic kanamycins can be employed for fungal specific diagnostic and therapeutic applications.

Phytochemical Profile and Anti-lipase Activity of Balkan Endemic Jurinea tzar-ferdinandii

Phytochemical study of the Balkan endemic J. tzar-ferdinandii Davidov allowed the identification of twenty-two components. β-Amyrin, lupeol, taraxasterol and Ψ-taraxasterol and their 3- O-acetates and 3- O-palmitates were identified by GC/MS. Six closely related sesquiterpene lactones and four flavones were isolated from the chloroform extract using column chromatography, and their structural identification was performed by spectral analyses. All isolated compounds are described for the first time in Jurinea species. The inhibitory potential of the total chloroform extract, fractions containing triterpenes, flavonoids and sesquiterpene lactones as well as individual compounds against a bacterial lipase from Candida rugosa (CRL) and a lipase from porcine pancrease (PPL) was evaluated. The half maximal inhibitory constants (IC50) for the two enzymes were in the range of 28–150 μg/mL. The strongest inhibitory activity was found for the total chloroform extract (29±1 μg/mL and 39±1 μg/mL for CRL and PPL, respectively.). Among the individual compounds, onopordopicrin was found to be the most potent inhibitor for CRL and PPL with IC50 values of 32±1 μg/mL and 36±1 μg/mL, respectively.

Candida species in tchapalo and bangui, two traditional alcoholic beverages from Côte d'Ivoire

The increase of infections due to non-Candida albicans species made it very necessary to conduct adequate characterization to be able to identify the species of Candida isolated from traditional fermented foods. In this study, based on their hue on Candida Chromogenic Agar medium, a total of 136 yeast strains were isolated from tchapalo and bangui. Molecular identification based on PCR-RFLP of internal transcribed spacers of rDNA (ITS) and sequencing of the ITS and the D1/D2 regions allowed us to assign these isolates to seven species: Candida tropicalis, Candida inconspicua, Candida rugosa, Saccharomyces cerevisiae, Kluyveromyces marxianus, Hanseniaspora guilliermondii, Trichosporon asahii. With the respect to each beverage, six species were found among with four species are regarded as opportunistic pathogens. From these, C. tropicalis, C. inconspicua and K. marxianus were the most commonly encountered. The enzyme activities of the potential pathogens assessed using API ZYM system showed that almost strains had esterase, esterase lipase, valine and cystine arylamidase, alpha chymotrypsin, alkaline phosphatase and naphthol phosphohydrolase activities. The activity of α-glucosidase was found only in C. tropicalis and C. inconspicua strains isolated from tchapalo while β-glucosidase activity was found in all strains from tchapalo and only in C. inconspicua isolated from bangui.

Microbial diversity in two traditional bacterial douchi from Gansu province in northwest China using Illumina sequencing

Douchi has been consumed as a flavoring ingredient for centuries. During production of douchi, numerous microorganisms play important roles in the hydrolysis and conversion of proteins and starch, which are related to the quality and flavor of the end product. Therefore, in the present study, the microbial diversity in two types of home-made traditional bacterial douchi from Gansu province in northwest China was studied by high-throughput sequencing, and a corresponding analysis of the bacterial and fungal communities were conducted. The results showed that geography may have impacted the fungal diversity and the bacterial and fungal species richness in the samples. The results also showed that the microbial community was significantly different in samples of different origin and the difference in the microbial community at the genus level was greater than at phylum level. Two dominant bacterial genera (Bacillus and Ignatzschineria) were common to the two samples, both of which had a relative abundance of more than 1%. Four bacterial genera (Staphylococcus, Aerococcus, Geobacillus, and Jeotgalicoccus) were dominant only in the sample from Qingyang, while another four (Carnobacterium, Proteus, Aneurinibacillus, and Enterococcus) were dominant only in the sample from Longnan. Two dominant fungal genera (Pichia and Candida) were shared by the two samples. Additionally, two genera (Rhodosporidium and Yarrowia) were dominant only in samples from Longnan. The functional genes of the bacteria present in samples indicated that a significant difference was observed in the bacterial community between samples of different origin. We also found that microbial interactions between bacterial and fungal communities in the samples were very complex. This study provides previously unknown information regarding the impact of the environment on microbial communities in douchi and lays a foundation for further investigations into food ecology in bacterial douchi.

Candida species diversity and antifungal susceptibility patterns in oral samples of HIV/AIDS patients in Baja California, Mexico

Candidiasis is the most common opportunistic fungal infection in HIV patients. The aims of this study were to identify the prevalence of carriers of Candida, Candida species diversity, and in vitro susceptibility to antifungal drugs. In 297 HIV/AIDS patients in Baja California, Mexico, Candida strains were identified by molecular methods (PCR-RFLP) from isolates of oral rinses of patients in Tijuana, Mexicali, and Ensenada. 56.3% of patients were colonized or infected with Candida. In Tijuana, there was a significantly higher percentage of carriers (75.5%). Out of the 181 strains that were isolated, 71.8% were Candida albicans and 28.2% were non-albicans species. The most common non-albicans species was Candida tropicalis (12.2%), followed by Candida glabrata (8.3%), Candida parapsilosis (2.2%), Candida krusei (1.7%), and Candida guilliermondii (1.1%). Candida dubliniensis was not isolated. Two associated species were found in 11 patients. In Mexicali and Ensenada, there was a lower proportion of Candida carriers compared to other regions in Mexico and worldwide, however, in Tijuana, a border town with many peculiarities, a higher carrier rate was found. In this population, only a high viral load was associated with oral Candida carriers. Other factors such as gender, use of antiretroviral therapy, CD4+ T-lymphocyte levels, time since diagnosis, and alcohol/ tobacco consumption, were not associated with Candida carriers.

Microbial dynamics during production of lesser mealworms (Alphitobius diaperinus) for human consumption at industrial scale

In this study, the microbial dynamics during an industrial production cyle of lesser mealworms (Alphitobius diaperinus), sold for human consumption, were characterised. The microbial numbers as well as the microbial diversity were generally higher for the substrate, existing of remaining feed, faeces and exuviae, than for the larvae. Most of the species-level operational taxonomic units, identified using Illumina MiSeq sequencing, that were present in the feed were also detected in the larvae and vice versa. However, bacterial diversity decreased in the larvae during rearing. These results suggested that the feed is an important determinant of the insect bacterial community, but that some bacterial species show a competitive advantage inside the insect gut and become dominant. A blanching treatment of the larvae after harvest reduced most microbial counts, but the number of aerobic endospores remained at 4.0 log cfu/g. Whereas food pathogens Salmonella spp., Listeria monocytogenes, Bacillus cereus or coagulase-positive staphylococci were not detected in our study, fungal isolates corresponding to the genera Aspergillus and Fusarium were recovered. Therefore, it cannot be excluded that mycotoxins were present. The results of this study contribute to a better understanding of the microbial dynamics and food safety aspects during the production of edible insects.

High Virulence and Antifungal Resistance in Clinical Strains of Candida albicans

Antifungal resistance and virulence properties of Candida albicans are a growing health problem worldwide. To study the expression of virulence and azole resistance genes in 39 clinical strains of C. albicans, we used a model of infection of human vaginal epithelial cells with C. albicans strains isolated from Mexican women with vulvovaginal candidiasis (VVC). The strains were identified by PCR amplification of the ITS1 and ITS2 regions of rRNA. The detection and expression of virulence genes and azole resistance genes MDR1 and CDR1 were performed using PCR and RT-PCR, respectively. All strains were sensitive to nystatin and 38 (97.4%) and 37 (94.9%) were resistant to ketoconazole and fluconazole, respectively. ALS1, SAP4–SAP6, LIP1, LIP2, LIP4, LIP6, LIP7, LIP9, LIP10, and PLB1-PLB2 were present in all strains; SAP1 was identified in 37 (94.8%) isolates, HWP1 in 35 (89.7%), ALS3 in 14 (35.8%), and CDR1 in 26 (66.6%). In nearly all of the strains, ALS1, HWP1, SAP4–SAP6, LIP1–LIP10, PLB1, and PLB2 were expressed, whereas CDR1 was expressed in 20 (51.3%) and ALS3 in 14 (35.8%). In our in vitro model of infection with C. albicans, the clinical strains showed different expression profiles of virulence genes in association with the azole resistance gene CDR1. The results indicate that the strains that infect Mexican patients suffering from VVC are highly virulent and virtually all are insensitive to azoles.

Are the Conventional Commercial Yeast Identification Methods Still Helpful in the Era of New Clinical Microbiology Diagnostics? A Meta-Analysis of Their Accuracy

Accurate identification of pathogenic species is important for early appropriate patient management, but growing diversity of infectious species/strains makes the identification of clinical yeasts increasingly difficult. Among conventional methods that are commercially available, the API ID32C, AuxaColor, and Vitek 2 systems are currently the most used systems in routine clinical microbiology. We performed a systematic review and meta-analysis to estimate and to compare the accuracy of the three systems, in order to assess whether they are still of value for the species-level identification of medically relevant yeasts. After adopting rigorous selection criteria, we included 26 published studies involving Candida and non-Candida yeasts that were tested with the API ID32C (674 isolates), AuxaColor (1,740 isolates), and Vitek 2 (2,853 isolates) systems. The random-effects pooled identification ratios at the species level were 0.89 (95% confidence interval [CI], 0.80 to 0.95) for the API ID32C system, 0.89 (95% CI, 0.83 to 0.93) for the AuxaColor system, and 0.93 (95% CI, 0.89 to 0.96) for the Vitek 2 system (P for heterogeneity, 0.255). Overall, the accuracy of studies using phenotypic analysis-based comparison methods was comparable to that of studies using molecular analysis-based comparison methods. Subanalysis of studies conducted on Candida yeasts showed that the Vitek 2 system was significantly more accurate (pooled ratio, 0.94 [95% CI, 0.85 to 0.99]) than the API ID32C system (pooled ratio, 0.84 [95% CI, 0.61 to 0.99]) and the AuxaColor system (pooled ratio, 0.76 [95% CI, 0.67 to 0.84]) with respect to uncommon species (P for heterogeneity, <0.05). Subanalysis of studies conducted on non-Candida yeasts (i.e., Cryptococcus, Rhodotorula, Saccharomyces, and Trichosporon) revealed pooled identification accuracies of ≥98% for the Vitek 2, API ID32C (excluding Cryptococcus), and AuxaColor (only Rhodotorula) systems, with significant low or null levels of heterogeneity (P > 0.05). Nonetheless, clinical microbiologists should reconsider the usefulness of these systems, particularly in light of new diagnostic tools such as matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, which allow for considerably shortened turnaround times and/or avoid the requirement for additional tests for species identity confirmation.

Antifungal susceptibilities of Candida glabrata species complex, Candida krusei, Candida parapsilosis species complex and Candida tropicalis causing invasive candidiasis in China: 3 year national surveillance

OBJECTIVES

To define the antifungal susceptibility patterns of the most common non-albicans Candida spp. in China.

METHODS

We evaluated the susceptibilities to nine antifungal drugs of Candida parapsilosis species complex, Candida tropicalis, Candida glabrata species complex and Candida krusei isolates from patients with invasive candidiasis at 11 hospitals over 3 years. Isolates were identified by MALDI-TOF MS supplemented by DNA sequencing. MICs were determined by Sensititre YeastOne(TM) using current clinical breakpoints/epidemiological cut-off values to assign susceptibility (or WT), and by CLSI M44-A2 disc diffusion for fluconazole and voriconazole.

RESULTS

Of 1072 isolates, 392 (36.6%) were C. parapsilosis species complex. C. tropicalis, C. glabrata species complex and C. krusei comprised 35.4%, 24.3% and 3.7% of the isolates, respectively. Over 99.3% of the isolates were of WT phenotype to amphotericin B and 5-flucytosine. Susceptibility/WT rates to azoles among C. parapsilosis species complex were ≥97.5%. However, 11.6% and 9.5% of C. tropicalis isolates were non-susceptible to fluconazole and voriconazole, respectively (7.1% were resistant to both). Approximately 14.3% of C. glabrata sensu stricto isolates (n = 258) were fluconazole resistant, and 11.6% of C. glabrata sensu stricto isolates were cross-resistant to fluconazole and voriconazole. All C. krusei isolates were susceptible/WT to voriconazole, posaconazole and itraconazole. Overall, 97.7%-100% of isolates were susceptible to caspofungin, micafungin and anidulafungin, but 2.3% of C. glabrata were non-susceptible to anidulafungin. There was no azole/echinocandin co-resistance. Disc diffusion and Sensititre YeastOne(TM) methods showed >95% categorical agreement for fluconazole and voriconazole.

CONCLUSIONS

In summary, reduced azole susceptibility was seen among C. tropicalis. Resistance to echinocandins was uncommon.

Resistance of Candida spp. to antifungal drugs in the ICU: where are we now?

Current increases in antifungal drug resistance in Candida spp. and clinical treatment failures are of concern, as invasive candidiasis is a significant cause of mortality in intensive care units (ICUs). This trend reflects the large and expanding use of newer broad-spectrum antifungal agents, such as triazoles and echinocandins. In this review, we firstly present an overview of the mechanisms of action of the drugs and of resistance in pathogenic yeasts, subsequently focusing on recent changes in the epidemiology of antifungal resistance in ICU. Then, we emphasize the clinical impacts of these current trends. The emergence of clinical treatment failures due to resistant isolates is described. We also consider the clinical usefulness of recent advances in the interpretation of antifungal susceptibility testing and in molecular detection of the mutations underlying acquired resistance. We pay particular attention to practical issues relating to ICU patient management, taking into account the growing threat of antifungal drug resistance.

Epidemiology and outcomes of invasive candidiasis due to non-albicans species of Candida in 2,496 patients: data from the Prospective Antifungal Therapy (PATH) registry 2004-2008

This analysis describes the epidemiology and outcomes of invasive candidiasis caused by non-albicans species of Candida in patients enrolled in the Prospective Antifungal Therapy Alliance (PATH Alliance) registry from 2004 to 2008. A total of 2,496 patients with non-albicans species of Candida isolates were identified. The identified species were C. glabrata (46.4%), C. parapsilosis (24.7%), C. tropicalis (13.9%), C. krusei (5.5%), C. lusitaniae (1.6%), C. dubliniensis (1.5%) and C. guilliermondii (0.4%); 111 infections involved two or more species of Candida (4.4%). Non-albicans species accounted for more than 50% of all cases of invasive candidiasis in 15 of the 24 sites (62.5%) that contributed more than one case to the survey. Among solid organ transplant recipients, patients with non-transplant surgery, and patients with solid tumors, the most prevalent non-albicans species was C. glabrata at 63.7%, 48.0%, and 53.8%, respectively. In 1,883 patients receiving antifungal therapy on day 3, fluconazole (30.5%) and echinocandins (47.5%) were the most frequently administered monotherapies. Among the 15 reported species, 90-day survival was highest for patients infected with either C. parapsilosis (70.7%) or C. lusitaniae (74.5%) and lowest for patients infected with an unknown species (46.7%) or two or more species (53.2%). In conclusion, this study expands the current knowledge of the epidemiology and outcomes of invasive candidiasis caused by non-albicans species of Candida in North America. The variability in species distribution in these centers underscores the importance of local epidemiology in guiding the selection of antifungal therapy.

Three clustered cases of candidemia caused by Candida quercitrusa and mycological characteristics of this novel species

We investigated three nosocomial Candida quercitrusa candidemia cases occurring within 2 months in a Chinese hospital. Isolates were identifiable only by DNA sequencing of the rRNA genes. Genetic (via random amplified polymorphic DNA [RAPD]) and protein mass spectral (via matrix-assisted laser desorption ionization-time of flight mass spectrometry [MALDI-TOF MS]) analyses yielded identical profiles suggesting an outbreak. The fluconazole MICs of all the strains were 16 to 32 μg/ml.

Systematic review and new insights into the molecular characterization of the Candida rugosa species complex

Recently, Candida rugosa was characterized as a species complex comprising four taxa: C. rugosa sensu stricto, Candida pseudorugosa, Candida neorugosa and Candida mesorugosa. Although considered relatively rare, several clusters of candidemia due to C. rugosa complex had been reported presenting mortality rates close to 70%. In this work we discuss the systematization, phenotyping and molecular methods based on internal transcribed spacer region (ITS) sequencing and proteomic analyses for species identification, as well as clinical aspects of the C. rugosa complex. We performed a Bayesian phylogenetic analysis using 72 ITS sequences representative of C. rugosa complex isolates and related species within the genus. Biochemical, morphological and MALDI-TOF MS analyses were processed with C. rugosa complex type strains and related species isolates. We described that the phylogeny showed four distinct clades inferred with high posterior probabilities, corresponding to the four species within the C. rugosa complex, excluding C. pararugosa. Biochemical and morphological aspects distinguished only C. rugosa sensu stricto but were not sufficient to accurately identify species within the rest of the complex. Protein spectrum profiles differentiated all reference strains from different species analyzed. To our knowledge, we presented the first phylogenetic analysis using a large collection of ITS sequences as well as proteomic profiles generated from isolates of the C. rugosa complex and related species that can enlighten systematics, diagnostics and clinical research fields.

Overview of invasive fungal infections

The incidence of invasive fungal infections (IFIs) has seen a marked increase in the last two decades. This is especially evident among transplant recipients, patients suffering from AIDS, in addition to those in receipt of immunosuppressive therapy. Worryingly, this increased incidence includes infections caused by opportunistic fungi and emerging fungal infections which are resistant to or certainly less susceptible than others to standard antifungal agents. As a direct response to this phenomenon, there has been a resolute effort over the past several decades to improve early and accurate diagnosis and provide reliable screening protocols thereby promoting the administration of appropriate antifungal therapy for fungal infections. Early diagnosis and treatment with antifungal therapy are vital if a patient is to survive an IFI. Substantial advancements have been made with regard to both the diagnosis and subsequent treatment of an IFI. In parallel, stark changes in the epidemiological profile of these IFIs have similarly occurred, often in direct response the type of antifungal agent being administered. The effects of an IFI can be far reaching, ranging from increased morbidity and mortality to increased length hospital stays and economic burden.

Candida mesorugosa sp. nov., a novel yeast species similar to Candida rugosa, isolated from a tertiary hospital in Brazil

Candida rugosa is a yeast species that is emerging as a causative agent of invasive infection, particularly in Latin America. Recently, C. pseudorugosa was proposed as a new species closely related to C. rugosa. We evaluated in this investigation the genetic heterogeneity within the C. rugosa species complex. All clinical isolates used in this study were identified phenotypically as C. rugosa but were genotypically different from the C. rugosa type, ATCC 10571. RAPD marker analysis revealed less than 83% similarity between our clinical isolates and the C. rugosa type strain. The D1/D2 region sequences of our clinical isolates showed 98% identity with C. rugosa but only 94-95% identity with C. pseudorugosa. The ITS rDNA sequences of the Brazilian isolates showed 91% identity with the C. rugosa ATCC 10571 ITS sequence. Network and Bayesian analyses of ITS and housekeeping gene sequences separated our clinical isolates into different branches from C. rugosa type strain. These differences are sufficient to reassign our isolates to a distinct species, named C. mesorugosa.

Molecular identification and antifungal susceptibility testing of clinical isolates of the Candida rugosa species complex and proposal of the new species Candida neorugosa

Candida rugosa is a poorly known fungal species occasionally involved in human infections. A molecular analysis of the sequences of the D1/D2 domains and the internal transcribed spacer (ITS) region of the ribosomal genes of 24 clinical isolates phenotypically identified as C. rugosa demonstrated that only 10 (41.6%) isolates belonged to that species. The other isolates were identified as Candida pararugosa (41.6%) and Candida pseudorugosa (8.3%). The remaining two isolates, from human and equine infections, respectively, were clearly different from the others and represent a new species proposed here as Candida neorugosa. The closest species by D1/D2 sequences was the type strain of C. rugosa, with only 92.3% similarity. C. neorugosa can also be differentiated from all other species of the C. rugosa complex by phenotypic features. The eight antifungal drugs tested showed high in vitro activity against the 24 isolates included in the study.

First case report of bloodstream infection due to a Candida species closely related to the novel species Candida pseudorugosa

Candida pseudorugosa is a novel species closely related to Candida rugosa for which only one case has been reported. We report the first case of a bloodstream infection in humans caused by a Candida sp. closely related to C. pseudorugosa. We contribute evidence to show this organism as a potential human pathogen that may be misidentified by conventional methods, also pointing out its lower sensitivity to azoles and other antifungal agents.

Lessons from animal studies for the treatment of invasive human infections due to uncommon fungi

Clinical experience in the management of opportunistic infections, especially those caused by less common fungi, is, due to their rarity, very scarce; therefore, the most effective treatments remain unknown. The ever-increasing numbers of fungal infections due to opportunistic fungi have repeatedly proven the limitations of the antifungal armamentarium. Moreover, some of these fungi, such as Fusarium spp. or Scedosporium spp., are innately resistant to almost all the available antifungal drugs, which makes the development of new and effective therapies a high priority. Since it is difficult to conduct randomized clinical trials in these uncommon mycoses, the use of animal models is a good alternative for evaluating new therapies. This is an extensive review of the numerous studies that have used animal models for this purpose against a significant number of less common fungi. A table describing the different studies performed on the efficacy of the different drugs tested is included for each fungal species. In addition, there is a summary table showing the conclusions that can be derived from the analysis of the studies and listing the drugs that showed the best results. Considering the wide variability in the response to the antifungals that the different strains of a given species can show, the table highlights the drugs that showed positive results using at least two parameters for evaluating efficacy against at least two different strains without showing any negative results. These data can be very useful for guiding the treatment of rare infections when there is very little experience or when controversial results exist, or when treatment fails.

In vitro susceptibility of a large collection of Candida Strains against fluconazole and voriconazole by using the CLSI disk diffusion assay

We evaluated all Candida spp. isolates obtained from patients admitted to two tertiary care hospitals between 1999 and 2003 in the city of São Paulo, Brazil. The in vitro activities of fluconazole (FCZ) and voriconazole were determined by the agar disk diffusion test using the Clinical and Laboratory Standards Institute M44-A guidelines. The inhibition zone diameters were read and interpreted automatically by the BIOMIC(®) image-analysis plate reader system. We tested a total of 4,625 strains, including 2,393 strains of C. albicans (51.7%), 658 of C. tropicalis (14.2%), 503 of C. glabrata (10.9%), 495 of C. parapsilosis (10.7%), 292 of C. rugosa (6.3%), 195 of C. guilliermondii (4.2%) and 89 of other Candida species (2.0%). Only 2.0% of the strains tested were classified as dose-dependent susceptible (DDS), and 5.8% of them were resistant to FCZ. The resistance or DDS to fluconazole was verified mainly among C. glabrata (7.8%), C. krusei (67.9%) and C. rugosa (65.1%). Voriconazole exhibited better activity in vitro than fluconazole, even in isolates fluconazole resistant. The resistance of fluconazole and voriconazole did not increase in the isolates of Candida spp. during the evaluated period.

Epidemiology of candidaemia in critically ill trauma patients: experiences of a level I trauma centre in North India

There is a need to understand the epidemiology and risk factors associated with candidaemia in critically ill trauma patients. The rise in incidence of non-albicans candidaemia and the emergence of antifungal resistance have made such a study necessary. A prospective laboratory-based surveillance study was performed over a period of 21 months (April 2008-December 2009) at a level I trauma centre in New Delhi, India. All blood culture samples positive for Candida were processed for microbial identification by standard methods. Identification was carried out by conventional methods, using chromogenic medium (CHROMagar Candida) and by the automated Vitek 2 system. These isolates were characterized for their susceptibility to amphotericin B, fluconazole, flucytosine and voriconazole. Eighty-nine episodes of candidaemia occurred in 89 patients during the study period. The incidence was 0.71 episodes per 1000 patient days. A total of 136 Candida isolates were obtained, with non-albicans Candida species accounting for over 80 %. Candida rugosa, a rarely isolated pathogen, accounted for 25 (18.4 %) of the isolates, and 5.9 % of the isolates were resistant to fluconazole. None of the isolates showed resistance against amphotericin B, flucytosine or voriconazole. The present study revealed that non-albicans Candida species caused most of the cases of candidaemia in the trauma patients. The isolation of C. rugosa from a large number of cases highlights the ability of this rarely reported pathogen to cause bloodstream infections. The presence of azole resistance among many of the Candida isolates is a matter of concern.

What do we know about Candida guilliermondii? A voyage throughout past and current literature about this emerging yeast

Candida guilliermondii is an uncommon isolate throughout most of the world, the behaviour of which as an environmental fungus, a human saprophyte and an agent of serious infections has been emphasised over the years. Notably, illnesses caused by this pathogen mostly involve compromised cancer hosts and commonly lead patients to unfavourable outcomes. It is of concern that the yeast may acquire or inherently express reduced in vitro sensitivity to all antifungal classes, although widespread resistance has not yet been described, and poor correlation exists between MICs and clinical outcome. However, the organism appears as constitutively less susceptible to polyenes and echinocandins than other yeast-like fungi, so that the emergence of such pathogen in the clinical settings is of concern and may appear as a new challenge in the context of mycoses and antifungal therapy.

Candida rugosa: a possible emerging cause of candidaemia in trauma patients

INTRODUCTION

Candida rugosa appears to be emerging as a distinctive cause of candidaemia in recent years. Candidaemia due to this species is important to recognise because of its decreased susceptibility to azoles.

MATERIALS AND METHODS

We retrospectively evaluated a cluster of C. rugosa candidaemia occurring in critically ill trauma patients from a level I trauma centre of India. During the period from July 2008 to September 2009, a total of 28 blood samples from 19 patients were found to be positive for C. rugosa. Genetic relatedness among 17 C. rugosa isolates were characterised by the random amplified polymorphic DNA (RAPD) assay using M13 primers. These isolates were also characterised for their susceptibility to four antifungal agents, amphotericin B, fluconazole, flucytosine and voriconazole.

RESULTS

In our study, 21% of C. rugosa isolates were resistant to fluconazole, whereas 100% susceptibility to amphotericin B, flucytosine and voriconazole was noted. Thirteen out of the 19 patients (68.4%) with C. rugosa candidaemia died. Of these, six had received antifungal therapy after confirmation of fungaemia.

DISCUSSION

Prior to this cluster, C. rugosa had never been identified as a cause of infection at our centre. Due to the retrospective nature of the evaluation of these cases, the source of this possible outbreak could not be traced. Nevertheless, to the best of our knowledge, this is the largest cluster of cases of C. rugosa candidaemia reported from a single institution in the English literature.

Characterization of yeasts colonizing in healthy individuals

Opportunistic yeast pathogens may switch from harmless commensal to pathogenic relationships with the host under different conditions. They usually cause superficial infections, but may be the agents of more significant infections in immunocompromised patients. To investigate yeast colonization in the oral cavities of clinically healthy individuals, we collected oral swabs from 323 students and staff at the National Health Research Institutes, Taiwan. A total of 49 (15.2%) volunteers were colonized by low levels of yeasts and of these, only 3 (6.1%) were co-colonized by more than one species. Among the 52 isolates, comprising seven fungal genera and 13 species, Candida albicans (57.7%) was the dominant species, followed by Candida parapsilosis (15.4%). There was only one isolate of C. parapsilosis that showed, in vitro, a high (2 μg/ml) minimum inhibitory concentration (MIC) to amphotericin B. There were six (11.5%) isolates with fluconazole MICs ≥ 64 μg/ml and all of them were non-Candida species. With the exception of Cryptococcus albidus, the remaining five isolates had voriconazole MICs ≥ 4 μg/ml. In addition, there was one C. albicans isolate with relatively high fluconazole (32 μg/ml) and voriconazole (4 μg/ml) MICs.

Epidemiology of invasive mycoses in North America

The incidence of invasive mycoses is increasing, especially among patients who are immunocompromised or hospitalized with serious underlying diseases. Such infections may be broken into two broad categories: opportunistic and endemic. The most important agents of the opportunistic mycoses are Candida spp., Cryptococcus neoformans, Pneumocystis jirovecii, and Aspergillus spp. (although the list of potential pathogens is ever expanding); while the most commonly encountered endemic mycoses are due to Histoplasma capsulatum, Coccidioides immitis/posadasii, and Blastomyces dermatitidis. This review discusses the epidemiologic profiles of these invasive mycoses in North America, as well as risk factors for infection, and the pathogens' antifungal susceptibility.