Host-pathogen interactions upon Candida auris infection: fungal behaviour and immune response in Galleria mellonella.

Candida auris has globally emerged as a multidrug-resistant fungus linked to healthcare-associated outbreaks. There is still limited evidence on its virulence, pathogenicity determinants, and complex host-pathogen interactions. This study analyzes the in vivo fungal behaviour, immune response, and host-pathogen interactions upon C. auris infection compared to C. albicans and C. parapsilosis in G. mellonella. This was performed by immunolabelling fungal structures and larval plasmatocytes and using a quantitative approach incorporating bioinformatic morphometric techniques into the study of microbial pathogenesis. C. auris presents a remarkably higher immunogenic activity than expected at its moderate degree of tissue invasion. It induces a greater inflammatory response than C. albicans and C. parapsilosis at the expense of plasmatocyte nodule formation, especially in non-aggregative strains. It specifically invades the larval respiratory system, in a pattern not previously observed in other Candida species, and presents inter-phenotypic tissue tropism differences. C. auris filaments in vivo less frequently than C. albicans or C. parapsilosis mostly through pseudohyphal growth. Filamentation might not be a major pathogenic determinant in C. auris, as less virulent aggregative phenotypes form pseudohyphae to a greater extent. C. auris has important both interspecific and intraspecific virulence and phenotype heterogeneity, with aggregative phenotypes of C. auris sharing characteristics with low pathogenic species such as C. parapsilosis. Our work suggests that C. auris owns an important morphogenetic plasticity that distinguishes it from other yeasts of the genus. Routine phenotypic identification of aggregative or non-aggregative phenotypes should be performed in the clinical setting as it may impact patient management.

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.

The transcription factor Ndt80 is a repressor of Candida parapsilosis virulence attributes.

Candida parapsilosis is an emergent opportunistic yeast among hospital settings that affects mainly neonates and immunocompromised patients. Its most remarkable virulence traits are the ability to adhere to prosthetic materials, as well as the formation of biofilm on abiotic surfaces. The Ndt80 transcription factor was identified as one of the regulators of biofilm formation by C. parapsilosis; however, its function in this process was not yet clarified. By knocking out NDT80 (CPAR2-213640) gene, or even just one single copy of the gene, we observed substantial alterations of virulence attributes, including morphogenetic changes, adhesion and biofilm growth profiles. Both ndt80Δ and ndt80ΔΔ mutants changed colony and cell morphologies from smooth, yeast-shaped to crepe and pseudohyphal elongated forms, exhibiting promoted adherence to polystyrene microspheres and notably, forming a higher amount of biofilm compared to wild-type strain. Interestingly, we identified transcription factors Ume6, Cph2, Cwh41, Ace2, Bcr1, protein kinase Mkc1 and adhesin Als7 to be under Ndt80 negative regulation, partially explaining the phenotypes displayed by the ndt80ΔΔ mutant. Furthermore, ndt80ΔΔ pseudohyphae adhered more rapidly and were more resistant to murine macrophage attack, becoming deleterious to such cells after phagocytosis. Unexpectedly, our findings provide the first evidence for a direct role of Ndt80 as a repressor of C. parapsilosis virulence attributes. This finding shows that C. parapsilosis Ndt80 functionally diverges from its homolog in the close related fungal pathogen C. albicans.

A medical epopee: recurrent fungal endocarditis, heart transplantation and chylopericardium.

BACKGROUND: Candida prosthetic endocarditis is associated with high mortality rates and valve replacement surgery, together with antifungal treatment, play a major role in eradicating the fungal infection. Valve reoperations in these scenarios may be relatively common due to the high infection relapse rates and, in some cases, heart transplantation may be an imposing therapy for infection resolution and for the heart failure related to the myocardial reoperation injury. Among the many postoperative complications related to heart transplantation, chylopericardium is a rare but challenging example. CASE PRESENTATION: We report the case of a 55-year-old man who was admitted to our hospital with a 1-month history of progressive dyspnea and fatigue. His past medical history included four open-heart surgeries for aortic and mitral valve replacement due to recurrent Candida parapsilosis infective endocarditis. Transthoracic echocardiogram showed a markedly reduced left ventricular systolic function and normofunctioning bioprosthetic valves. An inotropic dependency condition led to heart transplantation surgery. In the early postoperative period, a persistent chylous fluid started to drain from the pericardial tube, compatible with the diagnosis of chylopericardium. The lack of clinical response to total parenteral nutrition and intravenous infusion of octreotide imposed the need of interventional radiology with diagnostic lymphography through cisterna chyli puncture and thoracic duct catheterization, confirming the presence of a lymphatic fistula. A successful treatment outcome was achieved with percutaneous thoracic duct embolization using coils and n-butyl-cyanoacrilate glue, possibiliting hospital discharge. CONCLUSIONS: Fungal endocarditis requires combined treatment (surgical and antimicrobial) for eradication. Valve replacement, while necessary, may lead to severe ventricular deterioration and heart transplantation may be the only viable therapeutic solution. Among the several postoperative complications of heart transplantation, chylopericardium is an uncommon and defiant example. Advances in interventional radiology like the percutaneous embolization allow a less invasive and highly efficient approach for this complication.

Candida parapsilosis Infection: A Multilocus Microsatellite Genotyping-Based Survey Demonstrating an Outbreak in Hospitalized Patients.

Microsatellite analysis identifies specific genotypes and the genetic relationship between strains. Our objective was to analyze the genotypes of C. parapsilosis strains isolated on different wards of a Tertiary-Referral University Center. We evaluated 70 C. parapsilosis strains in total, isolated from samples of patients admitted to five different wards over two years (January 2015-December 2016). Eight microsatellite markers were selected, and two multiplex PCR assays were set up for microsatellite analysis. The 70 strains, examined at eight microsatellite loci, showed 46 different multilocus genotypes profiles. A total of 74 alleles were detected, with an average of 9.25 alleles per locus. The most variable loci were CP6 and CP4, with 20 and 15 alleles, respectively. Four clusters were detected in four out of five wards. A significant cluster that involved 16 patients in the General Surgery department was also found in two patients who had been transferred to the General Medicine ward. Two multiplex PCRs allowed us to minimize costs, define genotypes and study the isolates' genetic diversity with extreme accuracy, demonstrating the high discriminative power of the microsatellite markers. Molecular epidemiology constitutes an appropriate tool for evaluating horizontal transmission of C. parapsilosis in different clinical settings. Microsatellite genotyping and the utilization of Bruvo's genetic distance are suitable for detecting and appraising nosocomial fungal infections.

Triazole Evolution of Candida parapsilosis Results in Cross-Resistance to Other Antifungal Drugs, Influences Stress Responses, and Alters Virulence in an Antifungal Drug-Dependent Manner.

The number of invasive infections caused by Candida species is increasing worldwide. The incidence of candidiasis cases caused by non-albicans Candida species, such as Candida parapsilosis, is also increasing, and non-albicans Candida species are currently responsible for more invasive infections than C. albicans Additionally, while the development of azole resistance during invasive disease with C. albicans remains uncommon, azole-resistant C. parapsilosis strains are frequently isolated in the hospital setting. In this study, we applied direct selection to generate azole-adapted and azole-evolved C. parapsilosis strains in order to examine the effect of azole resistance development on fungal viability and pathogenesis progression. Depending on the drug applied, the different evolved strains developed distinct cross-resistance patterns: the fluconazole-evolved (FLUEVO) and voriconazole-evolved (VOREVO) strains gained resistance to fluconazole and voriconazole only, while posaconazole evolution resulted in cross-resistance to all azoles and the posaconazole-evolved (POSEVO) strains showed higher echinocandin MIC values than the FLUEVO and VOREVO strains. Whole-genome sequencing results identified the development of different resistance mechanisms in the evolved strains: the FLUEVO and VOREVO strains harbored amino acid substitutions in Mrr1p (A808T and N394Y, respectively), and the POSEVO strain harbored an amino acid change in Erg3p (D14Y). By revealing increased efflux pump activity in both the FLUEVO and the VOREVO strains, along with the altered sterol composition of the POSEVO strain, we now highlight the impact of the above-mentioned amino acid changes in C. parapsilosis azole resistance development. We further revealed that the virulence of this species was only slightly or partially affected by fluconazole and voriconazole adaptation, while it significantly decreased after posaconazole adaptation. Our results suggest that triazole adaptation can result in azole cross-resistance and that this process may also result in virulence alterations in C. parapsilosis, depending on the applied drug.IMPORTANCECandida parapsilosis causes life-threatening fungal infections. In the last 2 decades, the increasing number of azole-resistant C. parapsilosis clinical isolates has been attributable to the overuse and misuse of fluconazole, the first-line antifungal agent most commonly used in several countries. To date, the range of applicable antifungal drugs is limited. As a consequence, it is essential to understand the possible mechanisms of antifungal resistance development and their effect on virulence in order to optimize antifungal treatment strategies in the clinical setting. Our results revealed that the prolonged exposure to azoles resulted not only in azole resistance but also in cross-resistance development. Our data further indicate that resistance development may occur through different mechanisms that can also alter the virulence of C. parapsilosis These results highlight the consequences of prolonged drug usage and suggest the need for developing alternative antifungal treatment strategies in clinical practice.

The Transcriptional Aftermath in Two Independently Formed Hybrids of the Opportunistic Pathogen Candida orthopsilosis.

Interspecific hybridization can drive evolutionary adaptation to novel environments. The Saccharomycotina clade of budding yeasts includes many hybrid lineages, and hybridization has been proposed as a source for new pathogenic species. Candida orthopsilosis is an emerging opportunistic pathogen for which most clinical isolates are hybrids, each derived from one of at least four independent crosses between the same two parental lineages. To gain insight into the transcriptomic aftermath of hybridization in these pathogens, we analyzed allele-specific gene expression in two independently formed hybrid strains and in a homozygous strain representative of one parental lineage. Our results show that the effect of hybridization on overall gene expression is rather limited, affecting ∼4% of the genes studied. However, we identified a larger effect in terms of imbalanced allelic expression, affecting ∼9.5% of the heterozygous genes in the hybrids. This effect was larger in the hybrid with more extensive loss of heterozygosity, which may indicate a tendency to avoid loss of heterozygosity in these genes. Consistently, the number of shared genes with allele-specific expression in the two independently formed hybrids was higher than random expectation, suggesting selective retention. Some of the imbalanced genes have functions related to pathogenicity, including zinc transport and superoxide dismutase activities. While it remains unclear whether the observed imbalanced genes play a role in virulence, our results suggest that differences in allele-specific expression may add an additional layer of phenotypic plasticity to traits related to virulence in C. orthopsilosis hybrids.IMPORTANCE How new pathogens emerge is an important question that remains largely unanswered. Some emerging yeast pathogens are hybrids originated through the crossing of two different species, but how hybridization contributes to higher virulence is unclear. Here, we show that hybrids selectively retain gene regulation plasticity inherited from the two parents and that this plasticity affects genes involved in virulence.

In vitro characterization of virulence factors among species of the Candida parapsilosis complex.

INTRODUCTION: Candida parapsilosis complex species differ from each other with regard to their prevalence and virulence. METHODS: The hydrolytic enzyme activity, biofilm production, and adhesion to epithelial cells were analyzed in 87 C. parapsilosis complex strains. RESULTS: Among the studied isolates, 97.7%, 63.2%, and 82.8% exhibited very strong proteinase, esterase, and hemolysin activity, respectively. All the C. parapsilosis complex isolates produced biofilms and presented an average adherence of 96.0 yeasts/100 epithelial cells. CONCLUSIONS: Our results show that Candida parapsilosis complex isolates showed different levels of enzyme activity, biofilm production, and adhesion to epithelial cells.

Candida isolates causing candidemia show different degrees of virulence in Galleria mellonella.

We aim to assess intra- and interspecies differences in the virulence of Candida spp. strains causing candidemia using the invertebrate Galleria mellonella model. We studied 739 Candida spp. isolates (C. albicans [n = 373], C. parapsilosis [n = 203], C. glabrata [n = 92], C. tropicalis [n = 53], and C. krusei [n = 18]) collected from patients with candidemia admitted to Gregorio Marañon Hospital (Madrid, Spain). Species-specific infecting inocula (yeast cells/larva) were adjusted (5 × 105 [C. albicans, and C. tropicalis], 2 × 106-5 × 106 [C. parapsilosis, C. glabrata, and C. krusei]) and used to infect 10 larvae per isolate; percentage of survival and median survival per isolate were calculated. According to the interquartile range of the median survival, isolates with a median survival under P25 were classified as of high-virulence and isolates with a median survival over P75 as of low virulence. The median survival of larvae infected with different species was variable: C. albicans (n = 2 days, IQR <1-3 days), C. tropicalis (n = 2 days, IQR 1.5-4 days), C. parapsilosis (n = 2 days, IQR 2-3.5 days), C. glabrata (n = 3 days, IQR 2-3 days), and C. krusei (n = 7 days, 6.5->8 days) (P < .001). Differences in virulence among species were validated by histological examination (day +1 post-infection) in the larvae infected by the isolates of each virulence category and species. Virulence-related gene expression in C. albicans isolates did not reach statistical significance. We report species-specific virulence patterns of Candida spp. and show that isolates within a given species have different degrees of virulence in the animal model.

CpALS4770 and CpALS4780 contribution to the virulence of Candida parapsilosis.

The ability of yeast to adhere to biotic and abiotic surfaces represents an essential trait during the early stages of infection. Agglutinin-like sequence (Als) cell-wall proteins play a key role in adhesion of Candida species. Candida parapsilosis genome encompasses 5 ALS members, of which only the role of CPAR2_404800 has been elucidated. The present project was aimed at investigating the contribution of C. parapsilosis Als proteins by generating edited strains lacking functional Als proteins. CPAR2_404770 and CPAR2_404780, further indicated as CpALS4770 and CpALS4780, were selected for the generation of single and double edited strains using an episomal CRISPR/Cas9 technology. Phenotypic characterization of mutant strains revealed that editing of both genes had no impact on the in vitro growth of C. parapsilosis or on morphogenesis. Notably, CpALS4770-edited strain showed a reduction of biofilm formation and adhesive properties to human buccal cells (HBECs). Conversely, single CpALS4780-edited strain did not show any difference compared to the wild-type strain in all the assays performed, while the double CpALS4770-CpALS4780 mutant revealed an increased ability to produce biofilm, a hyper-adhesive phenotype to HBECs, and a marked tendency to form cellular aggregates. Murine vaginal infection experiments indicated a significant reduction in CFUs recovered from BALC/c mice infected with single and double edited strains, compared to those infected with the wild-type strain. These finding clearly indicate that CpAls4770 plays a role in adhesion to biotic and abiotic surfaces, while both CpALS4770 and CpALS4780 genes are required for C. parapsilosis ability to colonize and persist in the vaginal mucosa.

In vitro characterization of virulence factors among species of the Candida parapsilosis complex

Abstract INTRODUCTION: Candida parapsilosis complex species differ from each other with regard to their prevalence and virulence. METHODS: The hydrolytic enzyme activity, biofilm production, and adhesion to epithelial cells were analyzed in 87 C. parapsilosis complex strains. RESULTS: Among the studied isolates, 97.7%, 63.2%, and 82.8% exhibited very strong proteinase, esterase, and hemolysin activity, respectively. All the C. parapsilosis complex isolates produced biofilms and presented an average adherence of 96.0 yeasts/100 epithelial cells. CONCLUSIONS: Our results show that Candida parapsilosis complex isolates showed different levels of enzyme activity, biofilm production, and adhesion to epithelial cells.

Filamentation Is Associated with Reduced Pathogenicity of Multiple Non-albicans Candida Species.

Candidiasis affects a wide variety of immunocompromised and medically compromised patients. Candida albicans, a major human fungal pathogen, accounts for about 50% of all cases, while the remainder are caused by the less pathogenic non-albicans Candida species (NACS). These species are believed to be less pathogenic, in part, because they do not filament as readily or robustly as C. albicans, although definitive evidence is lacking. To address this question, we used strains for two NACS, Candida tropicalis and Candida parapsilosis, which were genetically engineered to constitutively express the key transcriptional regulator UME6 and drive strong filamentation both in vitro and during infection in vivo Unexpectedly, both strains showed a dramatic reduction in organ fungal burden in response to UME6 expression. Consistent with these findings, we observed that a C. tropicalis hyperfilamentous mutant was significantly reduced and a filamentation-defective mutant was slightly increased for organ fungal burden. Comprehensive immune profiling generally did not reveal any significant changes in the host response to UME6 expression in the NACS that could explain the increased clearance of infection. Interestingly, whole-genome transcriptional profiling indicated that while genes important for filamentation were induced by UME6 expression in C. tropicalis and C. parapsilosis, other genes involved in a variety of processes important for pathogenesis were strongly downregulated. These findings suggest that there are fundamental evolutionary differences in the relationship between morphology and pathogenicity among Candida species and that NACS do not necessarily possess the same virulence properties as C. albicansIMPORTANCE Many immunocompromised individuals, including HIV/AIDS and cancer patients, are susceptible to candidiasis. About half of all cases are caused by the major fungal pathogen Candida albicans, whereas the remainder are due to less pathogenic non-albicans Candida species (NACS). Generation of filamentous cells represents a major virulence property of C. albicans, and the NACS are believed to be less pathogenic, in part, because they do not filament as well as C. albicans does. To address this question, we determined the pathogenicity of two NACS strains that have been genetically engineered to promote filamentation during infection. Surprisingly, these strains showed a dramatic reduction in pathogenicity. The host immune response did not appear to be affected. However, unlike C. albicans, filamentation of the NACS was associated with downregulation of several genes important for pathogenicity processes. Our results suggest that there are fundamental evolutionary differences in the relationship between filamentation and pathogenesis in NACS compared to C. albicans.

Functional Characterization of Secreted Aspartyl Proteases in Candida parapsilosis.

Candida parapsilosis is an emerging non-albicans Candida species that largely affects low-birth-weight infants and immunocompromised patients. Fungal pathogenesis is promoted by the dynamic expression of diverse virulence factors, with secreted proteolytic enzymes being linked to the establishment and progression of disease. Although secreted aspartyl proteases (Sap) are critical for Candida albicans pathogenicity, their role in C. parapsilosis is poorly elucidated. In the present study, we aimed to examine the contribution of C. parapsilosisSAPP genes SAPP1, SAPP2, and SAPP3 to the virulence of the species. Our results indicate that SAPP1 and SAPP2, but not SAPP3, influence adhesion, host cell damage, phagosome-lysosome maturation, phagocytosis, killing capacity, and cytokine secretion by human peripheral blood-derived macrophages. Purified Sapp1p and Sapp2p were also shown to efficiently cleave host complement component 3b (C3b) and C4b proteins and complement regulator factor H. Additionally, Sapp2p was able to cleave factor H-related protein 5 (FHR-5). Altogether, these data demonstrate the diverse, significant contributions that SAPP1 and SAPP2 make to the establishment and progression of disease by C. parapsilosis through enabling the attachment of the yeast cells to mammalian cells and modulating macrophage biology and disruption of the complement cascade.IMPORTANCE Aspartyl proteases are present in various organisms and, among virulent species, are considered major virulence factors. Host tissue and cell damage, hijacking of immune responses, and hiding from innate immune cells are the most common behaviors of fungal secreted proteases enabling pathogen survival and invasion. C. parapsilosis, an opportunistic human-pathogenic fungus mainly threatening low-birth weight neonates and children, possesses three SAPP protein-encoding genes that could contribute to the invasiveness of the species. Our results suggest that SAPP1 and SAPP2, but not SAPP3, influence host evasion by regulating cell damage, phagocytosis, phagosome-lysosome maturation, killing, and cytokine secretion. Furthermore, SAPP1 and SAPP2 also effectively contribute to complement evasion.

Epidemiology and prognostic factors of nosocomial candidemia in Northeast Brazil: A six-year retrospective study.

Candidemia has been considered a persistent public health problem with great impact on hospital costs and high mortality. We aimed to evaluate the epidemiology and prognostic factors of candidemia in a tertiary hospital in Northeast Brazil from January 2011 to December 2016. Demographic and clinical data of patients were retrospectively obtained from medical records and antifungal susceptibility profiling was performed using the broth microdilution method. A total of 68 episodes of candidemia were evaluated. We found an average incidence of 2.23 episodes /1000 admissions and a 30-day mortality rate of 55.9%. The most prevalent species were Candida albicans (35.3%), Candida tropicalis (27.4%), Candida parapsilosis (21.6%) and Candida glabrata (11.8%). Higher mortality rates were observed in cases of candidemia due to C. albicans (61.1%) and C. glabrata (100%), especially when compared to C. parapsilosis (27.3%). Univariate analysis revealed some variables which significantly increased the probability of death: older age (P = 0.022; odds ratio [OR] = 1.041), severe sepsis (P < 0.001; OR = 8.571), septic shock (P = 0.035; OR = 3.792), hypotension (P = 0.003; OR = 9.120), neutrophilia (P = 0.046; OR = 3.080), thrombocytopenia (P = 0.002; OR = 6.800), mechanical ventilation (P = 0.009; OR = 8.167) and greater number of surgeries (P = 0.037; OR = 1.920). Multivariate analysis showed that older age (P = 0.040; OR = 1.055), severe sepsis (P = 0.009; OR = 9.872) and hypotension (P = 0.031; OR = 21.042) were independently associated with worse prognosis. There was no resistance to amphotericin B, micafungin or itraconazole and a low rate of resistance to fluconazole (5.1%). However, 20.5% of the Candida isolates were susceptible dose-dependent (SDD) to fluconazole and 7.7% to itraconazole. In conclusion, our results could assist in the adoption of strategies to stratify patients at higher risk for developing candidemia and worse prognosis, in addition to improve antifungal management.

The diagnostic value of (1,3)-ß-D-glucan alone or combined with traditional inflammatory markers in neonatal invasive candidiasis.

BACKGROUND: Asymptom of invasive candidiasis (IC) and low positive rate of blood culture lead to delay diagnose of neonatal infection. Serum (1,3)-ß-D-glucan (BDG) performs well in adult IC, but its use in neonatal IC is unclear. We evaluated the use of BDG, procalcitonin (PCT), high-sensitive C-reactive protein (hsCRP) or platelet count (PC) in neonatal IC. METHODS: We collected the data of neonates admitted to our institute. Eighty neonates were enrolled, and divided into IC group, bacterial infection (BI) group and control (CTRL) group. We analyzed the difference of these indicators between groups, and generated Receiver operator characteristic (ROC) curve. The value of BDG in antifungal therapy efficacy assessment was also investigated. RESULTS: The BDG level was higher in IC group compared with BI and CTRL group. C. albicans lead to significant increase of BDG compared with C. parapsilosis. IC group had highest hsCRP level and lowest PC. PCT level was similar between groups. ROC showed that BDG or hsCRP performs well in neonatal IC, the optimal cut-off for BDG was 13.69 mg/ml. Combined BDG with hsCRP, PCT and PC increased diagnostic value. Serum BDG level was decreased during antifungal treatment. CONCLUSION: Serum BDG performs well in identification of neonatal IC and in monitoring the antifungal therapy efficacy.

Recurrent arthritis caused by Candida parapsilosis: a case report and literature review.

BACKGROUND: Candida arthritis is extremely rare and also represents a major challenge of diagnosis and treatment. Here we reported a rare case of recurrent arthritis caused by Candida parapsilosis. CASE PRESENTATION: A 56-year-old Chinese male suffered from recurrent pain and swelling in his right knee after several times of "small needle-knife" acupuncture and corticosteroid injection of the joint. Candida parapsilosis was cultured in his synovial fluid and identified by sequencing of its Internal Transcribed Spacer (ITS) gene. Here we present the radiological characteristics, arthroscopic pictures, and synovium pathology of this patient. Also, blood test and chemical analysis of his synovial fluid were listed as well as the ITS sequence of this Candida species identified. The patient underwent thorough arthroscopic debridement and then set on fluconazole 400 mg daily for 12 months. His symptoms resolved and no relapse was observed on the last follow-up. Additionally, a brief but comprehensive review of C. parapsilosis arthritis episodes from past to now were studied. CONCLUSION: With the detailed clinical information reported in this case and our literature review, we hope they would add to our knowledge of C. parapsilosis arthritis - its clinical settings, laboratory features, radiological characteristics, arthroscopic findings and experience of management.

Correlating Genotype and Phenotype in the Asexual Yeast Candida orthopsilosis Implicates ZCF29 in Sensitivity to Caffeine.

Candida orthopsilosis is diploid asexual yeast that causes human disease. Most C. orthopsilosis isolates arose from at least four separate hybridizations between related, but not identical, parents. Here, we used population genomics data to correlate genotypic and phenotypic variation in 28 C. orthopsilosis isolates. We used cosine similarity scores to identify 65 variants with potential high-impact (deleterious effects) that correlated with specific phenotypes. Of these, 19 were Single Nucleotide Polymorphisms (SNPs) that changed stop or start codons, or splice sites. One variant resulted in a premature stop codon in both alleles of the gene ZCF29 in C. orthopsilosis isolate 185, which correlated with sensitivity to nystatin and caffeine. We used CRISPR-Cas9 editing to introduce this polymorphism into two resistant C. orthopsilosis isolates. Introducing the stop codon resulted in sensitivity to caffeine and to ketoconazole, but not to nystatin. Our analysis shows that it is possible to associate genomic variants with phenotype in asexual Candida species, but that only a small amount of genomic variation can be easily explored.

Asymptomatic catheter-related venous thrombosis in a child with cystic fibrosis: When to treat?

The use of central venous catheters (CVCs) in patients with cystic fibrosis is associated with an increased incidence of right atrial thrombosis. Practically, the management of CVC-related right atrial thrombosis presents a challenge as there are no clinical trials or systematic reviews in pediatric patients with cystic fibrosis. We describe a case of a 5-year-old child who presented with a CVC-related infection due to Candida parapsilosis. Echocardiogram revealed the presence of an incidental thrombus, measuring 1.4 cm × 0.4 cm, at the tip of the catheter, adherent to the right atrial wall and discrete from the tricuspid valve leaflets. Imaging was performed at monthly intervals and showed spontaneous resolution of the thrombus after six months. Follow-up blood cultures were negative, and the course of the patient was uneventful.

Candida parapsilosis: from Genes to the Bedside.

Patients with suppressed immunity are at the highest risk for hospital-acquired infections. Among these, invasive candidiasis is the most prevalent systemic fungal nosocomial infection. Over recent decades, the combined prevalence of non-albicans Candida species outranked Candida albicans infections in several geographical regions worldwide, highlighting the need to understand their pathobiology in order to develop effective treatment and to prevent future outbreaks. Candida parapsilosis is the second or third most frequently isolated Candida species from patients. Besides being highly prevalent, its biology differs markedly from that of C. albicans, which may be associated with C. parapsilosis' increased incidence. Differences in virulence, regulatory and antifungal drug resistance mechanisms, and the patient groups at risk indicate that conclusions drawn from C. albicans pathobiology cannot be simply extrapolated to C. parapsilosis Such species-specific characteristics may also influence their recognition and elimination by the host and the efficacy of antifungal drugs. Due to the availability of high-throughput, state-of-the-art experimental tools and molecular genetic methods adapted to C. parapsilosis, genome and transcriptome studies are now available that greatly contribute to our understanding of what makes this species a threat. In this review, we summarize 10 years of findings on C. parapsilosis pathogenesis, including the species' genetic properties, transcriptome studies, host responses, and molecular mechanisms of virulence. Antifungal susceptibility studies and clinician perspectives are discussed. We also present regional incidence reports in order to provide an updated worldwide epidemiology summary.

High-resolution fingerprinting of Candida parapsilosis isolates suggests persistence and transmission of infections among neonatal intensive care unit patients in Kuwait.

Candida parapsilosis causes ~35% of all candidemia cases in neonates. High-resolution fingerprinting of C. parapsilosis isolates from neonatal intensive care unit (NICU) patients in Maternity Hospital (MH) was performed to identify epidemiologically related strains. Sixty-eight bloodstream/colonizing strains isolated from 59 NICU patients, two isolates from health care workers (HCWs) from MH and 18 bloodstream isolates from two other hospitals were used. Six microsatellite markers were employed, isolates were assigned a numerical microsatellite genotype (MSG), dendrogram was constructed and similarities between genotypes were visualized by minimum spanning tree. Fifty bloodstream isolates from MH yielded 37 MSGs with 20 isolates clustering in 7 MSGs. Duplicate isolates and colonizing strains yielded same/highly similar MSG as bloodstream isolates. Colonizing strains from two non-candidemia patients yielded unique MSGs while others belonged to a cluster. All isolates from HCWs and from two other hospitals belonged to unique MSGs. Cluster isolates came from patients in NICU-1 or from neonates in NICU-1 and other NICUs. Clonal complexes comprising closely related genotypes indicative of microevolution were also detected. Our data show that some C. parapsilosis strains have persisted in MH environment over several years and these endemic genotypes were transmitted to other patients in NICU-1 and/or other nearby NICUs.