Clinical, Epidemiological and Laboratory Features of Invasive Candida parapsilosis Complex Infections in a Brazilian Pediatric Reference Hospital during the COVID-19 Pandemic

The present study aimed to describe the clinical, epidemiological and laboratory characteristics of invasive candidiasis by C. parapsilosis complex (CPC) in a Brazilian tertiary pediatric hospital during the COVID-19 pandemic. Clinical samples were processed in the BACT/ALERT® 3D system or on agar plates. Definitive identification was achieved by MALDI-TOF MS. Antifungal susceptibility was initially analyzed by the VITEK 2 system (AST-YS08 card) and confirmed by the CLSI protocol. Patient data were collected from the medical records using a structured questionnaire. CPC was recovered from 124 patients over an 18-month period, as follows: C. parapsilosis (83.87%), C. orthopsilosis (13.71%) and C. metapsilosis (2.42%). Antifungal resistance was not detected. The age of the patients with invasive CPC infections ranged from <1 to 18 years, and most of them came from oncology-related sectors, as these patients were more affected by C. parapsilosis. C. orthopsilosis infections were significantly more prevalent in patients from critical care units. Invasive infections caused by different pathogens occurred in 75 patients up to 30 days after the recovery of CPC isolates. Overall, 23 (18.55%) patients died within 30 days of CPC diagnosis. Catheter removal and antifungal therapy were important measures to prevent mortality. COVID-19 coinfection was only detected in one patient.

Global Prevalence of Antifungal-Resistant Candida parapsilosis: A Systematic Review and Meta-Analysis

A reliable estimate of Candida parapsilosis antifungal susceptibility in candidemia patients is increasingly important to track the spread of C. parapsilosis bloodstream infections and define the true burden of the ongoing antifungal resistance. A systematic review and meta-analysis (SRMA) were conducted aiming to estimate the global prevalence and identify patterns of antifungal resistance. A systematic literature search of the PubMed, Scopus, ScienceDirect and Google Scholar electronic databases was conducted on published studies that employed antifungal susceptibility testing (AFST) on clinical C. parapsilosis isolates globally. Seventy-nine eligible studies were included. Using meta-analysis of proportions, the overall pooled prevalence of three most important antifungal drugs; Fluconazole, Amphotericin B and Voriconazole resistant C. parapsilosis were calculated as 15.2% (95% CI: 9.2-21.2), 1.3% (95% CI: 0.0-2.9) and 4.7% (95% CI: 2.2-7.3), respectively. Based on study enrolment time, country/continent and AFST method, subgroup analyses were conducted for the three studied antifungals to determine sources of heterogeneity. Timeline and regional differences in C. parapsilosis prevalence of antifungal resistance were identified with the same patterns among the three antifungal drugs. These findings highlight the need to conduct further studies to assess and monitor the growing burden of antifungal resistance, to revise treatment guidelines and to implement regional surveillance to prevent further increase in C. parapsilosis drug resistance emerging recently.

Echinocandins Susceptibility Patterns of 2,787 Yeast Isolates: Importance of the Thresholds for the Detection of FKS Mutations

Since echinocandins are recommended as first line therapy for invasive candidiasis, detection of resistance, mainly due to alteration in FKS protein, is of main interest. EUCAST AFST recommends testing both MIC of anidulafungin and micafungin, and breakpoints (BPs) have been proposed to detect echinocandin-resistant isolates. We analyzed MIC distribution for all three available echinocandins of 2,787 clinical yeast isolates corresponding to 5 common and 16 rare yeast species, using the standardized EUCAST method for anidulafungin and modified for caspofungin and micafungin (AM3-MIC). In our database, 64 isolates of common pathogenic species were resistant to anidulafungin, according to the EUCAST BP, and/or to caspofungin, using our previously published threshold (AM3-MIC ≥ 0.5 mg/L). Among these 64 isolates, 50 exhibited 21 different FKS mutations. We analyzed the capacity of caspofungin AM3-MIC and anidulafungin MIC determination in detecting isolates with FKS mutation. They were always identified using caspofungin AM3-MIC and the local threshold while some isolates were misclassified using anidulafungin MIC and EUCAST threshold. However, both methods misclassified four wild-type C. glabrata as resistant. Based on a large data set from a single center, the use of AM3-MIC testing for caspofungin looks promising in identifying non-wild-type C. albicans, C. tropicalis and P. kudiravzevii isolates, but additional multicenter comparison is mandatory to conclude on the possible superiority of AM3-MIC testing compared to the EUCAST method.

Detection and Molecular Identification of Eight Candida Species in Clinical Samples by Simplex PCR

Systemic candidiasis is a frequent opportunistic mycosis that can be life-threatening. Its main etiological agent is Candida albicans; however, the isolation of non-albicans Candida species has been increasing. Some of these species exhibit greater resistance to antifungals, so the rapid and specific identification of yeasts is crucial for a timely diagnosis and optimal treatment of patients. Multiple molecular assays have been developed, based mainly on polymerase chain reaction (PCR), showing high specificity and sensitivity to detect and identify Candida spp. Nevertheless, its application in diagnosis has been limited due to specialized infrastructure or methodological complexity. The objective of this study was to develop a PCR assay that detects and identifies some of the most common pathogenic Candida species and evaluate their diagnostic utility in blood samples and bronchial lavage. A pair of oligonucleotides was designed, CandF and CandR, based on sequence analysis of the 18S-ITS1-5.8S-ITS2-28S region of the rDNA of Candida spp., deposited in GenBank. The designed oligonucleotides identified C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei/Pichia kudriazevii, C. guilliermondii/Meyerozyma guilliermondii, C. lusitaniae/Clavispora lusitaniae, and C. dubliniensis using simplex PCR based on the amplicon size, showing a detection limit of 10 pg/μL of DNA or 10³ yeasts/mL. Based on cultures as the gold standard, it was determined that the sensitivity (73.9%), specificity (96.3%), and the positive (94.4%) and negative (81.2%) predictive values of the PCR assay with the designed oligonucleotides justify their reliable use in diagnosis.

Identification of a novel Candida metapsilosis isolate reveals multiple hybridization events

Candida metapsilosis is a member of the Candida parapsilosis species complex, a group of opportunistic human pathogens. Of all the members of this complex, C. metapsilosis is the least virulent, and accounts for a small proportion of invasive Candida infections. Previous studies established that all C. metapsilosis isolates are hybrids, originating from a single hybridization event between two lineages, parent A and parent B. Here, we use MinION and Illumina sequencing to characterize a C. metapsilosis isolate that originated from a separate hybridization. One of the parents of the new isolate is very closely related to parent A. However, the other parent (parent C) is not the same as parent B. Unlike C. metapsilosis AB isolates, the C. metapsilosis AC isolate has not undergone introgression at the mating type-like locus. In addition, the A and C haplotypes are not fully collinear. The C. metapsilosis AC isolate has undergone loss of heterozygosity with a preference for haplotype A, indicating that this isolate is in the early stages of genome stabilization.

Species distribution, azole resistance and related molecular mechanisms in invasive Candida parapsilosis complex isolates: Increase in fluconazole resistance in 21 years

BACKGROUND

Candida parapsilosis complex consists of three species, the prevalence and geographical distribution of which might vary. Increasing rates of fluconazole resistance among C. parapsilosis complex were reported from various centres.

OBJECTIVES

Aim of this study was to identify invasive C. parapsilosis complex strains up to species level, explore rates and molecular mechanisms of azole resistance and analyse temporal changes at a single centre.

METHODS

Isolates from blood cultures from 1997 to 2017 were included. Species were identified using RFLP of the SADH gene and confirmed with ITS sequencing when needed. In vitro susceptibility to fluconazole, voriconazole and posaconazole was tested and evaluated using EUCAST guidelines. Sequences of ERG11 and MRR1 genes were analysed for fluconazole non-susceptible isolates.

RESULTS

A total of 283 isolates from 181 patients were tested for azole susceptibility. All were C. parapsilosis sensu stricto, except one C. orthopsilosis. All three azoles were effective against 213 of the isolates from 135 patients, including one C. orthopsilosis. Fluconazole resistance was 13.3% (24/181 patients). While the first fluconazole-resistant isolates were detected in 2004, increase was evident after 2011. In ERG11, Y132F mutation was the most common among fluconazole non-susceptible isolates (71.7%), followed by G458S (10.9%) and D421N (4.3%). In MRR1, R405K (56.5%) and G927C (8.7%) were detected. However, association of these mutations to azole resistance is yet to be investigated.

CONCLUSIONS

Rising azole resistance rates in C. parapsilosis sensu stricto isolates particularly after 2011 were of concern. The well-known Y132F mutation was the predominant mechanism of azole resistance while accompanied with other genetic mutations.

Candida parapsilosis complex infection in a cutaneous lesion from a dog: Spotlight on an opportunistic pathogen of potential increasing importance

Fine-needle aspirates from a 1.5-cm cutaneous mass in a Cocker Spaniel were submitted for cytologic examination. Marked pyogranulomatous inflammation and fungal organisms were present, identified as Candida parapsilosis complex by MALDI-ToF following fungal culture. The fungal infection was considered secondary or an incidental finding, following the diagnosis of a benign keratinizing lesion by histopathologic examination of the excised mass. This case is presented to increase awareness and describe the cytologic features of a potential pathogen, which is of increasing importance in human medicine but has a limited presence in the veterinary literature despite the potential for a similar significance.

Comparative in vitro activities of seven antifungal drugs against clinical isolates of Candida parapsilosis complex

OBJECTIVE

Candida parapsilosis species complex, an important set of non-albicans Candida species, is known to cause candidaemia particularly in neonates and infants. However, the incidence has increased in recent years, owing to higher numbers of at individuals at risk for these infections. Our objective was to evaluate the in vitro susceptibility of clinical isolates of C. parapsilosis complex isolates from Iran to seven antifungal drugs.

MATERIAL AND METHODS

One hundred-one clinical isolates of C. parapsilosis species complex cultured from humans were included. Species identification had been previously confirmed by combined phenotypic characteristics, matrix-assisted laser desorption ionization-time of flight mass spectrometry-based assay and reconfirmed by DNA sequence analysis of the ITS rDNA region and D1/D2 gene. Minimum inhibitory concentrations (MICs) for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, micafungin and anidulafungin were determined against well-characterized isolates by broth microdilution susceptibility testing according to the CLSI M27-A3 guideline.

RESULTS

Species identifications were performed on 101 isolates, of which 88 (87.2%) C. parapsilosis sensu stricto and 13 (12.8%) C. orthopsilosis. Amphotericin B and posaconazole were the most active drugs with 100% of isolates being wild-type (WT). Voriconazole and micafungin, 99% of isolates were WT. The low activity was recorded for fluconazole and itraconazole with 93.1% and 89.1% of isolates being WT, respectively. At the species level, all Candida parapsilosis sensu stricto isolates were WT to amphotericin B and posaconazole and all Candida orthopsilosis isolates were WT to amphotericin B, voriconazole, posaconazole, anidulafungin and micafungin. In contrast, the highest rate of non-WT was observed in C. orthopsilosis to itraconazole (4 of 13, 30.8%).

CONCLUSIONS

Although almost all of the tested drugs demonstrated potent activity against C. parapsilosis species complex, it seems that more especially C. orthopsilosis isolates had decreased susceptibility to itraconazole. Further studies are needed to determine how these findings may switch into in vivo efficacy.

Exposure of Candida parapsilosis complex to agricultural azoles: An overview of the role of environmental determinants for the development of resistance

This work investigated the phenotypic behavior of Candida parapsilosis species complex in response to exposure to agricultural azoles and fluconazole. Three fluconazole-susceptible strains of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis were used. Initial minimum inhibitory concentrations (iMICs) for agricultural and clinical azoles were determined by broth microdilution. Then, the strains were exposed to tebuconazole, tetraconazole and fluconazole for 15 days, at concentrations that were two-folded daily, starting at one-eighth the iMIC (iMIC/8) up to 64 times iMIC (64xiMIC). After 15-day-exposure, antifungal susceptibility, biofilm formation, CDR, MDR and ERG expression were evaluated. The three cryptic species developed tolerance to the antifungals they were exposed and presented reduction (P < 0.05) in fluconazole susceptibility. In addition, C. parapsilosis sensu stricto and C. metapsilosis also presented reduced susceptibility to voriconazole, after fluconazole exposure. Azole exposure decreased (P < 0.05) biofilm production by C. parapsilosis sensu stricto and C. orthopsilosis and increased (P < 0.05) the expression of ERG11 in all tested strains. The results show that exposure to agricultural azoles and fluconazole induces changes in the phenotypic behavior and gene expression by the three cryptic species of C. parapsilosis complex, highlighting the importance of environmental determinants for the development of antifungal resistance.

Nosocomial outbreak of Candida parapsilosis sensu stricto fungaemia in a neonatal intensive care unit in China

BACKGROUND

Candida parapsilosis is a common agent of fungaemia, but few outbreaks of Candida parapsilosis infection have been reported in China.

AIM

To elaborate an outbreak of nosocomial Candida parapsilosis sensu stricto fungaemia in a neonatal intensive care unit (NICU) of a comprehensive hospital in China from July to October 2017.

METHODS

Epidemics and characteristics of fungaemia cases were investigated. Surveillance samples were collected. Vitek 2 Compact System, internal transcribed spacer sequencing, and random amplified polymorphic DNA (RAPD) typing were conducted to identify the isolates. Antifungal susceptibility test was performed for all bloodstream isolates.

FINDINGS

Sixteen neonates were diagnosed as Candida parapsilosis sensu stricto fungaemia during this period. Presenting symptoms included leucopenia, thrombocytopenia, and respiratory crackles. Fifteen cases were cured whereas one case who suffered from severe concomitant diseases died. The isolates were susceptible to fluconazole, amphotericin B, itraconazole, voriconazole, and 5-fluorocytosine. A total of 313 surveillance samples were collected, and Candida parapsilosis sensu stricto was identified from 16 environmental samples and one sample from an ultrasonographer's hand. The colonized locations included wiping cloths, faucets, sinks, operating table, puddles in the bathroom, a ventilator, and an ultrasonic probe. The RAPD patterns of all the Candida parapsilosis sensu stricto isolates from bloodstream and surveillance samples were identical. The outbreak was controlled after a series of infection control measures.

CONCLUSION

Contaminated environment was associated with this outbreak. Close attention to immunocompromised patients, thorough environmental disinfection and hand hygiene should be strengthened in NICU.

Development of the Human Mycobiome over the First Month of Life and across Body Sites

With the advent of next-generation sequencing and microbial community characterization, we are beginning to understand the key factors that shape early-life microbial colonization and associated health outcomes. Studies characterizing infant microbial colonization have focused mostly on bacteria in the microbiome and have largely neglected fungi (the mycobiome), despite their relevance to mucosal infections in healthy infants. In this pilot study, we characterized the skin, oral, and anal mycobiomes of infants over the first month of life (n = 17) and the anal and vaginal mycobiomes of mothers (n = 16) by internal transcribed spacer 2 (ITS2) amplicon sequencing. We found that infant mycobiomes differed by body site, with the infant mycobiomes at the anal sites being different from those at the skin and oral sites. The relative abundances of body site-specific taxa differed by birth mode, with significantly more Candida albicans fungi present on the skin of vaginally born infants on day 30 and significantly more Candida orthopsilosis fungi present in the oral cavity of caesarean section-born infants throughout the first month of life. We found the mycobiomes within individual infants to be variable over the first month of life, and vaginal birth did not result in infant mycobiomes that were more similar to the mother's vaginal mycobiome. Therefore, although vertical transmission of specific fungal isolates from mother to infant has been reported, it is likely that other sources (environment, other caregivers) also contribute to early-life mycobiome establishment. Thus, future longitudinal studies of mycobiome and bacterial microbiome codevelopment, with dense sampling from birth to beyond the first month of life, are warranted. IMPORTANCE Humans are colonized by diverse fungi (mycobiome), which have received much less study to date than colonizing bacteria. We know very little about the succession of fungal colonization in early life and whether it may relate to long-term health. To better understand fungal colonization and its sources, we studied the skin, oral, and anal mycobiomes of healthy term infants and the vaginal and anal mycobiomes of their mothers. Generally, infants were colonized by few fungal taxa, and fungal alpha diversity did not increase over the first month of life. There was no clear community maturation over the first month of life, regardless of body site. Key body-site-specific taxa, but not overall fungal community structures, were impacted by birth mode. Thus, additional studies to characterize mycobiome acquisition and succession throughout early life are needed to form a foundation for research into the relationship between mycobiome development and human disease.

MTL genotypes, phenotypic switching, and susceptibility profiles of Candida parapsilosis species group compared to Lodderomyces elongisporus

Reference isolates of Candida parapsilosis (n = 8), Candida metapsilosis (n = 6), Candida orthopsilosis (n = 7), and Lodderomyces elongisporus (n = 11) were analyzed to gain insight into their pathobiology and virulence mechanisms. Initial evaluation using BBL Chromagar Candida medium misidentified L. elongisporus isolates as C. albicans. Polymerase chain reaction analysis of isolate MTL idiomorphs revealed that all C. parapsilosis isolates were MTLa homozygous and no MTL α1, α2, a1, or a2 gene was detected in L. elongisporus isolates. For C. orthopsilosis, two isolates were MTLa homozygous and five were MTL-heterozygous. Similarly, one C. metapsilosis isolate was MTLα homozygous whereas five were MTL-heterozygous. Isolate phenotypic switching analysis revealed potential phenotypic switching in the MTLα homozygous C. metapsilosis isolate, resulting in concomitant elongated cell formation. Minimum inhibitory concentrations of fluconazole (FLC) and FK506, alone or in combination, were determined by checkerboard assay, with data analyzed using the fractional inhibitory concentration index model. Synergistic or additive effects of these compounds were commonly observed in C. parapsilosis and L. elongisporus isolates. No killer activity was observed in the studied isolates, as determined phenotypically. No significant difference in virulence was seen for the four species in a Galleria mellonella model (P > 0.05). In conclusion, our results demonstrated phenotypic switching of C. metapsilosis CBS 2315 and that FLC and FK506 represent a promising drug combination against C. parapsilosis and L. elongisporus. The findings of the present study contribute to our understanding of the biology, diagnosis, and new possible treatments of the C. parapsilosis species group and L. elongisporus.

Hyphal wall protein 1 gene: A potential marker for the identification of different Candida species and phylogenetic analysis

BACKGROUND AND PURPOSE

Hyphal wall protein 1 (HWP1) is an important adhesin which usually is expressed on the germ tube and hyphal surface produced by different Candida species. The hyphal wall protein-coding gene (HWP1) was evaluated as a novel identification and phylogenetic marker in Candida tropicalis, C. orthopsilosis, C. parapsilosis and C. glabrata.

MATERIALS AND METHODS

Initially, four specific primer pairs were designed, and the target was amplified and finally sequenced. A total of 77 Candida isolates from four different species were included in the study. Consensus sequences were used for the evaluation of phylogenetic tree using the CLC Genome Workbench, GENEIOUS, and MEGA softwares and the levels of nucleotide and amino acid polymorphism were assessed.

RESULTS

According to the results, the specific amplified fragments of HWP1 gene were useful for the differentiation of four species. Intra-species variation was observed only in C. tropicalis with two DNA types. The phylogenetic tree of Candida species based on the HWP1 gene showed consistency in topology with those inferred from other gene sequences.

CONCLUSION

We found that HWP1 gene was an excellent marker for the identification of non-albicansCandida species as well as the phylogenetic analysis of the most clinically significant Candida species.

Outbreak of candidemia caused by fluconazole resistant Candida parapsilosis strains in an intensive care unit

Background

Candidemia is an increasing problem in tertiary care hospitals worldwide. Here, we report the first outbreak of candidemia caused by fluconazole-resistant C. parapsilosis (FRCP) strains in Brazil.

Methods

This was a cross-sectional study of clinical and microbiological data of all candidemic episodes diagnosed from July 2011 to February 2012 in a 200-bed tertiary care hospital. Initial yeast identification and susceptibility testing were performed using the VITEK 2 - System. Isolates of Candida spp. resistant to fluconazole were sent to a reference laboratory (LEMI-UNIFESP) for further molecular identification and confirmation of resistance by CLSI microdilution test. A multivariate analysis was conducted to identify factors associated with FRCP infection.

Results

We identified a total of 40 critically ill patients with candidemia (15 women) with a median age of 70 years. The incidence of candidemia was 6 cases/1,000 patients admissions, including 28 cases (70 %) of infection with C. parapsilosis, 21 of which (75 %) were resistant to fluconazole. In only 19 % of FRCP candidemia cases had fluconazole been used previously. The results of our study indicated that diabetes is a risk factor for FRCP candidemia (p = 0.002). Overall, mortality from candidemia was 45 %, and mortality from episodes of FRCP infections was 42.9 %.

Conclusions

The clustering of incident cases in the ICU and molecular typing of strains suggest horizontal transmission of FRCP. Accurate vigilant monitoring for new nosocomial strains of FRCP is required.

Genome comparison of Candida orthopsilosis clinical strains reveals the existence of hybrids between two distinct subspecies

The Candida parapsilosis species complex comprises a group of emerging human pathogens of varying virulence. This complex was recently subdivided into three different species: C. parapsilosis sensu stricto, C. metapsilosis, and C. orthopsilosis. Within the latter, at least two clearly distinct subspecies seem to be present among clinical isolates (Type 1 and Type 2). To gain insight into the genomic differences between these subspecies, we undertook the sequencing of a clinical isolate classified as Type 1 and compared it with the available sequence of a Type 2 clinical strain. Unexpectedly, the analysis of the newly sequenced strain revealed a highly heterozygous genome, which we show to be the consequence of a hybridization event between both identified subspecies. This implicitly suggests that C. orthopsilosis is able to mate, a so-far unanswered question. The resulting hybrid shows a chimeric genome that maintains a similar gene dosage from both parental lineages and displays ongoing loss of heterozygosity. Several of the differences found between the gene content in both strains relate to virulent-related families, with the hybrid strain presenting a higher copy number of genes coding for efflux pumps or secreted lipases. Remarkably, two clinical strains isolated from distant geographical locations (Texas and Singapore) are descendants of the same hybrid line, raising the intriguing possibility of a relationship between the hybridization event and the global spread of a virulent clone.

The identification and differentiation of the Candida parapsilosis complex species by polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer region of the rDNA

Currently, it is accepted that there are three species that were formerly grouped under Candida parapsilosis: C. para- psilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. In fact, the antifungal susceptibility profiles and distinct virulence attributes demonstrate the differences in these nosocomial pathogens. An accurate, fast, and economical identification of fungal species has been the main goal in mycology. In the present study, we searched sequences that were available in the GenBank database in order to identify the complete sequence for the internal transcribed spacer (ITS)1-5.8S-ITS2 region, which is comprised of the forward and reverse primers ITS1 and ITS4. Subsequently, an in silico polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to differentiate the C. parapsilosis complex species. Ninety-eight clinical isolates from patients with fungaemia were submitted for analysis, where 59 isolates were identified as C. parapsilosis sensu stricto, 37 were identified as C. orthopsilosis, and two were identified as C. metapsilosis. PCR-RFLP quickly and accurately identified C. parapsilosis complex species, making this method an alternative and routine identification system for use in clinical mycology laboratories.

Molecular Identification and Echinocandin Susceptibility of Candida parapsilosis Complex Bloodstream Isolates in Italy, 2007-2014

The Candida parapsilosis group encompasses three species: C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Here, we describe the incidence and echinocandin susceptibility profile of bloodstream isolates of these three species collected from patients admitted to an Italian university hospital from 2007 to 2014. Molecular identification of cryptic species of the C. parapsilosis complex was performed using polymerase chain reaction amplification of the gene encoding secondary alcohol dehydrogenase, followed by digestion with the restriction enzyme BanI. Minimum inhibitory concentrations were determined using the broth microdilution method according to European Committee for Antimicrobial Susceptibility Testing (EUCAST EDef 7.2) and Clinical Laboratory Standards Institute (CLSI M27-A3) guidelines, and the results were compared with those obtained using the E-test and Sensititre methods. Of the 163 C. parapsilosis complex isolates, 136 (83.4%) were identified as C. parapsilosis, and 27 (16.6%) as C. orthopsilosis. The species-specific incidences were 2.9/10,000 admissions for C. parapsilosis and 0.6/10,000 admissions for C. orthopsilosis. No resistance to echinocandins was detected with any of the methods. The percent essential agreement (EA) between the EUCAST and E-test/Sensititre methods for anidulafungin, caspofungin, and micafungin susceptibility was, respectively, as follows: C. parapsilosis, 95.6/97.8, 98.5/88.2, and 93.4/96.3; C. orthopsilosis, 92.6/92.6, 96.3/77.8, and 63.0/66.7. The EA between the CLSI and E-test/Sensititre methods was, respectively, as follows: C. parapsilosis, 99.3/100, 98.5/89.0, and 96.3/98.5; C. orthopsilosis, 96.3/92.6, 100/81.5, and 92.6/88.9. Only minor discrepancies, ranging from 16.9% (C. parapsilosis) to 11.1% (C. orthopsilosis), were observed between the CLSI and E-test/Sensititre methods. In conclusion, this epidemiologic study shows a typical C. parapsilosis complex species distribution, no echinocandin resistance, and it reinforces the relevance of using commercially available microbiological methods to assess antifungal susceptibility. These data improve our knowledge of the national distribution of species of the psilosis group, as there are very few studies of these species in Italy.

Antifungal Susceptibility Patterns of Candida Species Recovered from Endotracheal Tube in an Intensive Care Unit

Aims. Biofilms formed by Candida species which associated with drastically enhanced resistance against most antimicrobial agents. The aim of this study was to identify and determine the antifungal susceptibility pattern of Candida species isolated from endotracheal tubes from ICU patients. Methods. One hundred forty ICU patients with tracheal tubes who were intubated and mechanically ventilated were surveyed for endotracheal tube biofilms. Samples were processed for quantitative microbial culture. Yeast isolates were identified to the species level based on morphological characteristics and their identity was confirmed by PCR-RFLP. Antifungal susceptibility testing was determined according to CLSI document (M27-A3). Results. Ninety-five strains of Candida were obtained from endotracheal tubes of which C. albicans (n = 34; 35.7%) was the most frequently isolated species followed by other species which included C. glabrata (n = 24; 25.2%), C. parapsilosis (n = 16; 16.8%), C. tropicalis (n = 12; 12.6%), and C. krusei (n = 9; 9.4%). The resulting MIC90 for all Candida species were in increasing order as follows: caspofungin (0.5 μg/mL); amphotericin B (2 μg/mL); voriconazole (8.8 μg/mL); itraconazole (16 μg/mL); and fluconazole (64 μg/mL). Conclusion. Candida species recovered from endotracheal tube are the most susceptible to caspofungin.

First isolation of Candida metapsilosis in Kuwait, an emerging global opportunistic pathogen

Invasive infections due to uncommon and rare yeast species are increasing worldwide in prevalence and are associated with high mortality rates. Here, we describe the first isolation and characterization of Candida metapsilosis cultured from the blood sample of a 10-year-old Saudi girl, who suffered from a neurodegenerative disorder, in Kuwait. The yeast isolate was identified by sequencing of ITS region and D1/D2 domains of rDNA. The report extends the geographic distribution of C. metapsilosis to the Middle East and highlights the emerging role of uncommon yeast species causing infections in susceptible hosts.

Simple, Low-Cost Detection of Candida parapsilosis Complex Isolates and Molecular Fingerprinting of Candida orthopsilosis Strains in Kuwait by ITS Region Sequencing and Amplified Fragment Length Polymorphism Analysis

Candida parapsilosis has now emerged as the second or third most important cause of healthcare-associated Candida infections. Molecular studies have shown that phenotypically identified C. parapsilosis isolates represent a complex of three species, namely, C. parapsilosis, C. orthopsilosis and C. metapsilosis. Lodderomyces elongisporus is another species phenotypically closely related to the C. parapsilosis-complex. The aim of this study was to develop a simple, low cost multiplex (m) PCR assay for species-specific identification of C. parapsilosis complex isolates and to study genetic relatedness of C. orthopsilosis isolates in Kuwait. Species-specific amplicons from C. parapsilosis (171 bp), C. orthopsilosis (109 bp), C. metapsilosis (217 bp) and L. elongisporus (258 bp) were obtained in mPCR. Clinical isolates identified as C. parapsilosis (n = 380) by Vitek2 in Kuwait and an international collection of 27 C. parapsilosis complex and L. elongisporus isolates previously characterized by rDNA sequencing were analyzed to evaluate mPCR. Species-specific PCR and DNA sequencing of internal transcribed spacer (ITS) region of rDNA were performed to validate the results of mPCR. Fingerprinting of 19 clinical C. orthopsilosis isolates (including 4 isolates from a previous study) was performed by amplified fragment length polymorphism (AFLP) analysis. Phenotypically identified C. parapsilosis isolates (n = 380) were identified as C. parapsilosis sensu stricto (n = 361), C. orthopsilosis (n = 15), C. metapsilosis (n = 1) and L. elongisporus (n = 3) by mPCR. The mPCR also accurately detected all epidemiologically unrelated C. parapsilosis complex and L. elongisporus isolates. The 19 C. orthopsilosis isolates obtained from 16 patients were divided into 3 haplotypes based on ITS region sequence data. Seven distinct genotypes were identified among the 19 C. orthopsilosis isolates by AFLP including a dominant genotype (AFLP1) comprising 11 isolates recovered from 10 patients. A rapid, low-cost mPCR assay for detection and differentiation of C. parapsilosis, C. orthopsilosis, C. metapsilosis and L. elongisporus has been developed.

The Genomic Aftermath of Hybridization in the Opportunistic Pathogen Candida metapsilosis

Candida metapsilosis is a rarely-isolated, opportunistic pathogen that belongs to a clade of pathogenic yeasts known as the C. parapsilosis sensu lato species complex. To gain insight into the recent evolution of C. metapsilosis and the genetic basis of its virulence, we sequenced the genome of 11 clinical isolates from various locations, which we compared to each other and to the available genomes of the two remaining members of the complex: C. orthopsilosis and C. parapsilosis. Unexpectedly, we found compelling genomic evidence that C. metapsilosis is a highly heterozygous hybrid species, with all sequenced clinical strains resulting from the same past hybridization event involving two parental lineages that were approximately 4.5% divergent in sequence. This result indicates that the parental species are non-pathogenic, but that hybridization between them formed a new opportunistic pathogen, C. metapsilosis, that has achieved a worldwide distribution. We show that these hybrids are diploid and we identified strains carrying loci for both alternative mating types, which supports mating as the initial mechanism for hybrid formation. We trace the aftermath of this hybridization at the genomic level, and reconstruct the evolutionary relationships among the different strains. Recombination and introgression -resulting in loss of heterozygosis- between the two subgenomes have been rampant, and includes the partial overwriting of the MTLa mating locus in all strains. Collectively, our results shed light on the recent genomic evolution within the C. parapsilosis sensu lato complex, and argue for a re-definition of species within this clade, with at least five distinct homozygous lineages, some of which having the ability to form hybrids.

Candida parapsilosis (sensu lato) isolated from hospitals located in the Southeast of Brazil: Species distribution, antifungal susceptibility and virulence attributes

Candida parapsilosis (sensu lato), which represents a fungal complex composed of three genetically related species - Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis, has emerged as an important yeast causing fungemia worldwide. The goal of the present work was to assess the prevalence, antifungal susceptibility and production of virulence traits in 53 clinical isolates previously identified as C. parapsilosis (sensu lato) obtained from hospitals located in the Southeast of Brazil. Species forming this fungal complex are physiologically/morphologically indistinguishable; however, polymerase chain reaction followed by restriction fragment length polymorphism of FKS1 gene has solved the identification inaccuracy, revealing that 43 (81.1%) isolates were identified as C. parapsilosis sensu stricto and 10 (18.9%) as C. orthopsilosis. No C. metapsilosis was found. The geographic distribution of these Candida species was uniform among the studied Brazilian States (São Paulo, Rio de Janeiro and Espírito Santo). All C. orthopsilosis and almost all C. parapsilosis sensu stricto (95.3%) isolates were susceptible to amphotericin B, fluconazole, itraconazole, voriconazole and caspofungin. Nevertheless, one C. parapsilosis sensu stricto isolate was resistant to fluconazole and another one was resistant to caspofungin. C. parapsilosis sensu stricto isolates exhibited higher MIC mean values to amphotericin B, fluconazole and caspofungin than those of C. orthopsilosis, while C. orthopsilosis isolates displayed higher MIC mean to itraconazole compared to C. parapsilosis sensu stricto. Identical MIC mean values to voriconazole were measured for these Candida species. All the isolates of both species were able to form biofilm on polystyrene surface. Impressively, biofilm-growing cells of C. parapsilosis sensu stricto and C. orthopsilosis exhibited a considerable resistance to all antifungal agents tested. Pseudohyphae were observed in 67.4% and 80% of C. parapsilosis sensu stricto and C. orthopsilosis isolates, respectively. The secretion of phytase (93% versus 100%), aspartic protease (88.4% versus 90%), esterase (20.9% versus 50%) and hemolytic factors (25.6% versus 40%) was detected in C. parapsilosis sensu stricto and C. orthopsilosis isolates, respectively; however, no phospholipase activity was identified. An interesting fact was observed concerning the caseinolytic activity, for which all the producers (53.5%) belonged to C. parapsilosis sensu stricto. Collectively, our results add new data on the epidemiology, antifungal susceptibility and production of potential virulence attributes in clinical isolates of C. parapsilosis complex.

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.

The calcineurin inhibitor cyclosporin A exhibits synergism with antifungals against Candida parapsilosis species complex

Candida parapsilosis complex comprises three closely related species, C. parapsilosis sensu stricto, Candida metapsilosis and Candida orthopsilosis. In the last decade, antifungal resistance to azoles and caspofungin among C. parapsilosis sensu lato strains has been considered a matter of concern worldwide. In the present study, we evaluated the synergistic potential of antifungals and the calcineurin inhibitor cyclosporin A (Cys) against planktonic and biofilms of C. parapsilosis complex from clinical sources. Susceptibility assays with amphotericin, fluconazole, voriconazole, caspofungin and Cys were performed by microdilution in accordance with Clinical and Laboratory Standards Institute guidelines. Synergy testing against planktonic cells of C. parapsilosis sensu lato strains was assessed by the chequerboard method. Combinations formed by antifungals with Cys were evaluated against mature biofilms in microtitre plates. No differences in the antifungal susceptibility pattern among species were observed, but C. parapsilosis sensu stricto strains were more susceptible to Cys than C. orthopsilosis and C. metapsilosis. Synergism between antifungals and Cys was observed in C. parapsilosis sensu lato strains. Combinations formed by antifungals and Cys were able to prevent biofilm formation and showed an inhibitory effect against mature biofilms of C. parapsilosis sensu stricto, C. metapsilosis and C. orthopsilosis. These results strengthen the potential of calcineurin inhibition as a promising approach to enhance the efficiency of antifungal drugs.

Characterization of virulence properties in the C. parapsilosis sensu lato species

The C. parapsilosis sensu lato group involves three closely related species, C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis. Although their overall clinical importance is dramatically increasing, there are few studies regarding the virulence properties of the species of the psilosis complex. In this study, we tested 63 C. parapsilosis sensu stricto, 12 C. metapsilosis and 18 C. orthopsilosis isolates for the ability to produce extracellular proteases, secrete lipases and form pseudohyphae. Significant differences were noted between species, with the C. metapsilosis strains failing to secrete lipase or to produce pseudohyphae. Nine different clinical isolates each of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis were co-cultured with immortalized murine or primary human macrophages. C. parapsilosis sensu stricto isolates showed a significantly higher resistance to killing by primary human macrophages compared to C. orthopsilosis and C. metapsilosis isolates. In contrast, the killing of isolates by J774.2 mouse macrophages did not differ significantly between species. However, C. parapsilosis sensu stricto isolates induced the most damage to murine and human macrophages, and C. metapsilosis strains were the least toxic. Furthermore, strains that produced lipase or pseudohyphae were most resistant to macrophage-mediated killing and produced the most cellular damage. Finally, we used 9 isolates of each of the C. parapsilosis sensus lato species to examine their impact on the survival of Galleriamellonella larvae. The mortality rate of G. mellonella larvae infected with C. metapsilosis isolates was significantly lower than those infected with C. parapsilosis sensu stricto or C. orthopsilosis strains. Taken together, our findings demonstrate that C. metapsilosis is indeed the least virulent member of the psilosis group, and also highlight the importance of pseudohyphae and secreted lipases during fungal-host interactions.

Comparison of Candida parapsilosis, Candida orthopsilosis, and Candida metapsilosis adhesive properties and pathogenicity

Retrospective studies indicate that Candida metapsilosis and Candida orthopsilosis each represents 1-10% of the infections/colonisations attributed to C. parapsilosis by conventional biochemical tests. Little is known on the virulence properties of these fungi and on their role in the establishment/progression of the infection. In this study, the adhesive properties of clinical isolates belonging to the 'psilosis' species were assessed in an in vitro model of co-incubation with human buccal epithelial cells (HBECs). Ectophosphatase activity was also measured for all isolates, since the activity of this enzyme has previously been linked to adhesion properties in C. parapsilosis. The results indicate that whilst C. parapsilosis and C. orthopsilosis strains showed similar adhesion abilities, C. metapsilosis isolates displayed a significantly lower ability to adhere to HBECs (P<0.05). No evidence of a correlation between ectophosphatase activity and adhesion was observed, and this finding was also confirmed by phosphatase inhibition experiments. Experimental vaginal candidiasis induced in oestrogen-treated mice with representative isolates of the 3 species indicated that mice infected with C. metapsilosis displayed a reduced vaginal fungal burden, especially in the early stages of the infection. The overall findings confirm that C. orthopsilosis has a comparable behaviour to C. parapsilosis, whilst C. metapsilosis seems to possess a reduced virulence potential.

Prevalence and antifungal susceptibility of Candida parapsilosis complex isolates collected from oral cavities of HIV-infected individuals

At present, few data are available on the prevalence and antifungal susceptibility of Candida parapsilosis complex isolates from HIV-infected individuals. The C. parapsilosis complex comprises three species, C. parapsilosis sensu stricto, C. metapsilosis and C. orthopsilosis. Fifteen of 318 Candida isolates were identified as members of the C. parapsilosis complex by PCR and restriction fragment length polymorphism (RFLP). The prevalence of C. parapsilosis complex isolates was 4.7 %, 2.2 % being identified as C. parapsilosis sensu stricto and 2.5 % as C. metapsilosis, while no C. orthopsilosis was isolated. This is believed to be the first study that has identified isolates of C. metapsilosis obtained from the oral cavity of HIV-infected individuals. Antifungal susceptibility tests indicated that all the isolates were susceptible to amphotericin B (AMB), fluconazole (FLC), ketoconazole (KTC), itraconazole (ITC), voriconazole (VRC) and caspofungin (CASPO). Although isolates of C. parapsilosis sensu stricto and C. metapsilosis were susceptible to FLC, isolates of C. metapsilosis showed a tendency for higher MICs (≥1.0 µg ml(-1)). Based upon the frequency of candidiasis and the fact that certain isolates of the C. parapsilosis complex respond differently to FLC therapy, our data may be of therapeutic relevance with respect to susceptibility and potential resistance to specific antifungal agents. Our data suggest that C. metapsilosis can be a human commensal; its importance as a pathogen has yet to be confirmed.