Süleyha Hilmioğlu Polat

Background: Mucormycosis is a life-threatening angioinvasive fungal infection that primarily affects immunocompromised individuals, especially those with diabetes mellitus or hematologic malignancies. Despite its clinical importance, a comprehensive synthesis of mucormycosis cases from Türkiye is lacking. This study aimed to review and synthesize the published case reports on mucormycosis in Türkiye systematically. Materials and Methods: Mucormycosis case reports from Türkiye published between 1 January 1966 and 30 November 2024 were reviewed and analyzed, with an emphasis on demographics, clinical characteristics, treatment strategies, and outcomes. Results: A total of 199 cases from 155 publications were included. Mean age was 47.7 years, and 51.8% of patients were male. Diabetes mellitus was the most frequent underlying condition (65.8%), followed by hematologic malignancies (16.6%). Rhino-cerebral involvement was the predominant clinical form (86.4%). Histopathological confirmation was reported in 91.0% of cases, whereas microbiological confirmation was available in 47.7%. Overall mortality was 43.7%. Surgical debridement was performed in 69.3% of cases, and crude mortality was lower among patients who underwent surgery than among those who did not. Liposomal amphotericin B was the most frequently reported antifungal agent. Conclusions: This study provides a national descriptive synthesis of published mucormycosis cases from Türkiye over nearly six decades. The findings highlight the predominance of diabetes-associated rhino-cerebral disease, frequent reliance on histopathology, and the importance of combined medical–surgical management in routine practice. Because the dataset is based on heterogeneous published case reports and case series spanning a long time period, treatment-outcome findings should be interpreted descriptively.

Antifungal tolerance can promote the emergence of resistance yet often incurs fitness costs for fungal pathogens. How tolerant populations compensate for these deficits and how they may be therapeutically targeted remain poorly understood. Here, we investigate four sequential Candida parapsilosis isolates recovered from a patient with persistent candidemia and failure of micafungin therapy. The infection was ultimately cleared with liposomal amphotericin B (LAMB). Whole-genome sequencing (WGS) confirmed clonal relatedness and the absence of known resistance mutations. Later isolates displayed marked cell wall remodeling (CWR), characterized by increased mannan and reduced β-glucan content, as revealed by microscopy and solid-state nuclear magnetic resonance. These isolates formed thicker biofilms and displayed enhanced echinocandin tolerance but paradoxically showed increased susceptibility to amphotericin B (AMB) in vitro and during systemic infection in mice. Despite a complex mutational landscape, transcriptomic profiling across planktonic and biofilm growth showed minimal divergence from the earliest isolate. Functionally, evolved isolates suppressed M1 macrophage polarization, dampened proinflammatory cytokine production, survived better during neutrophil interactions, and transiently increased fungal burden in vivo . These findings show that host-driven CWR could promote echinocandin tolerance while simultaneously sensitizing C. parapsilosis to AMB. Our results suggest that alternating echinocandin and LAMB therapy may effectively eliminate echinocandin-tolerant fungal populations. IMPORTANCE: Antifungal tolerance is increasingly recognized as a precursor to resistance, yet its clinical and biological consequences remain poorly defined. By analyzing sequential Candida parapsilosis isolates from a case of persistent candidemia, we show that cell wall remodeling is associated with echinocandin tolerance, alters host immune interactions, and increases susceptibility to amphotericin B (AMB). These findings reveal how tolerance-associated adaptations shape pathogen fitness during infection and highlight the therapeutic potential of alternating echinocandin and AMB therapy. This work advances our understanding of antifungal tolerance and suggests that exploiting opposing drug susceptibilities may improve treatment outcomes for challenging-to-treat Candida infections.

In recent decades, infections caused by C.parapsilosis have been increasingly reported, particularly strains of C.parapsilosis that are non-susceptible to

Background Homozygous mutations in the Caspase-associated recruitment domain 9 (CARD9) gene increase susceptibility to invasive fungal infections, particularly those caused by Candida species. This study aims to assess the spectrum of CARD9 gene mutations that predispose individuals in the Turkish population, especially children, to invasive fungal infections. Methods Our study included 30 patients who were admitted to Ege University due to invasive fungal infection or chronic mucocutaneous candidiasis between 2020 and 2023. Demographic and clinical data of the patients were recorded, and a sequence analysis of the CARD9 gene was performed. Results The median age of the patients was 1.8 years (interquartile range [IQR]: 11.8). Diagnoses included fungal endocarditis (n = 8, 26.6%), chronic mucocutaneous candidiasis (n = 7,23.3%), central nervous system (CNS) infections (n = 6,20%), candidemia (n = 4,13.3%), fungus ball in the kidney (n = 2, 6.7%), endophthalmitis ( n = 1, 3.3%), concurrent CNS and intra-abdominal infection (n = 1, 3.3%), and concurrent CNS infection and endophthalmitis (n = 1, 3.3%). All 12 exons and exon–intron junctions of the CARD9 (NM_052813.5) gene that encodes the CARD9 protein were analyzed. A disease-causing variant was detected in 2 patients (6.6%). One patient had a Pseudallescheria boydii brain abscess, and the other had an invasive fungal infection confirmed histopathologically. Conclusions Among the 30 patients with invasive fungal infections, a disease-causing CARD9 mutation was identified in 2 (6.6%) patients. While CARD9 mutations are known to be associated with invasive candidiasis, this study reports the first pediatric case of P. boydii infection associated with a CARD9 mutation.

Objectives: Worldwide emergence of clonal outbreaks caused by fluconazole‐resistant (FLCR) and the recent emergence of echinocandin‐ and multidrug‐resistant (ECR and MDR) Candida parapsilosis isolates pose serious threats to modern clinics. Conducting large‐scale epidemiological studies aimed at determining the genetic composition and antifungal resistance rates is necessary to devise antifungal stewardship and infection control strategies at international, national and local levels. Despite being severely hit by outbreaks due to FLCR C. parapsilosis isolates, such knowledge at the national level is lacking in Türkiye. Herein, we conducted a prospective multicentre study involving five major clinical centres in Türkiye to determine antifungal resistance rates, underlying mechanisms and genetic composition of all isolates.Methods: In total, 341 isolates were collected from 265 patients including clinical information. Antifungal susceptibility testing against common antifungals was performed in addition to sequencing of ERG11 and FKS1. Last, isolates were genotyped with short tandem repeat (STR) genotyping to investigate potential nosocomial transmission.Results: The FLCR rate was 26.7% (91/341), out of which 75.8% (69/91) harboured the ERG11^Y132F mutation. Patients infected with FLCR isolates had a higher mortality rate compared to their susceptible counterparts (49% for FLCR vs. 42% for susceptible). ECR rate was 2.1% (7/341) and isolates carried FKS1^{F652L/R658G/W1370R} mutations. Concerningly, four ECR isolates were MDR. FLCR isolates grouped in distinct clusters without evidence of inter‐hospital transmission, whereas large clusters containing susceptible isolates from all centres were noted.Conclusion: Overall, the increasing prevalence of FLCR C. parapsilosis at national level and the emergence of ECR and MDR isolates pose serious clinical challenges in Türkiye. Therefore, conducting large‐scale epidemiological studies are critical to determine the trend of antifungal resistance and to tailor pertinent antifungal stewardship and infection control strategies to effectively curb the spread of drug‐resistant C. parapsilosis.

Candida krusei also known as Pichia kudriavzevii is a potentially multidrug-resistant yeast because it is intrinsically resistant to fluconazole and develops acquired resistance to echinocandins and polyenes. Here, we aim to provide a better understanding of the epidemiology and transmission modes of C. krusei infections by comparing invasive bloodstream (n = 35) and non-invasive vaginal (n = 20) C. krusei isolates. The genetic relatedness of the isolates was assessed using a newly described short tandem repeat (STR) analysis and their sensitivity to eight antifungal compounds was evaluated by antifungal susceptibility testing using the CLSI microbroth dilution method. All C. krusei isolates revealed unique STR genotypes, indicating the absence of clonal transmission in the study group. Furthermore, no drug-resistant or non-wild-type isolates were identified. Our findings demonstrated high resolution of STR genotyping for the detection and simultaneous genetic analysis of multiple C. krusei strains in clinical samples and excellent in vitro activity of common antifungal agents against invasive strains. To gain insight into the mode of transmission and resistance development of C. krusei, we compared invasive bloodstream C. krusei isolates with non-invasive vaginal isolates using genotyping and susceptibility testing. All isolates demonstrated unique genotypes and no antifungal resistance was found, indicating the absence of clonal transmission and a high susceptibility to antifungals.

Small colony variants (SCVs) are relatively common among some bacterial species and are associated with poor prognosis and recalcitrant infections. Similarly, Candida glabrata – a major intracellular fungal pathogen – produces small and slow-growing respiratory-deficient colonies, termed “petite.” Despite reports of clinical petite C . glabrata strains, our understanding of petite behavior in the host remains obscure. Moreover, controversies exist regarding in-host petite fitness and its clinical relevance. Herein, we employed whole-genome sequencing (WGS), dual-RNAseq, and extensive ex vivo and in vivo studies to fill this knowledge gap. WGS identified multiple petite-specific mutations in nuclear and mitochondrially-encoded genes. Consistent with dual-RNAseq data, petite C . glabrata cells did not replicate inside host macrophages and were outcompeted by their non-petite parents in macrophages and in gut colonization and systemic infection mouse models. The intracellular petites showed hallmarks of drug tolerance and were relatively insensitive to the fungicidal activity of echinocandin drugs. Petite-infected macrophages exhibited a pro-inflammatory and type I IFN-skewed transcriptional program. Interrogation of international C . glabrata blood isolates ( n =1000) showed that petite prevalence varies by country, albeit at an overall low prevalence (0–3.5%). Collectively, our study sheds new light on the genetic basis, drug susceptibility, clinical prevalence, and host-pathogen responses of a clinically overlooked phenotype in a major fungal pathogen. Importance: Candida glabrata is a major fungal pathogen, which is able to lose mitochondria and form small and slow-growing colonies, called “petite”. This attenuated growth rate has created controversies and questioned the clinical importance of petiteness. Herein, we have employed multiple omicstechnologies and in vivo mouse models to critically assess the clinical importance of petite phenotype. Our WGS identifies multiple genes potentially underpinning petite phenotype. Interestingly, petite C. glabrata cells engulfed by macrophages are dormant and therefore are not killed by the frontline antifungal drugs. Interestingly, macrophages infected with petite cells mount distinct transcriptomic responses. Consistent with our ex-vivo observations, mitochondrial-proficient parental strains outcompete petites during systemic and gut colonization. Retrospective examination of C. glabrata isolates identified petite prevalence a rare entity, can significantly vary from country to country. Collectively, our study overcomes the existing controversies and provides novel insights regarding the clinical relevance of petite C. glabrata isolates.

Background: Candidemia is a life‐threatening infection in hospitalied children. This study aimed to evaluate candidemia's demographic and clinical characteristics and identify the risk factors and outcomes of Candida albicans (CA) and non‐albicans Candida (NAC) spp.Methods: A retrospective cohort was designed to evaluate paediatric patients with candidemia between January 2008 and December 2020.Results: A total of 342 episodes in 311 patients were evaluated. The median age of the patients was 2.1 years (1 month–17 years and 6 months), and 59.6% were male. The prevalence of NAC (67.5%) candidemia was higher than that of CA (32.5%). The most commonly isolated Candida species was Candida parapsilosis (43.3%), followed by C. albicans (32.5%), Candida glabrata (6.1%) and Candida tropicalis (5.0%). The length of hospital stay prior to the positive culture and the total length of hospital stay were longer in the NAC group (p = .003 and p = .006). The neutrophil count was lower in the NAC group (p = .007). In the multivariate analysis, total parenteral nutrition, antifungal prophylaxis and a history of coagulase‐negative staphylococci (CoNS) culture positivity in the past month were risk factors for developing candidemia due to NAC (p values were .003, .003 and .045). C. albicans and C. parapsilosis fluconazole resistance were 9.5% and 46.6%, respectively. The rates of amphotericin B resistance were 1.1% and 7.6% in C. albicans and C. parapsilosis, respectively. Mortality (14‐day and 30‐day) rates did not differ between the groups.Conclusions: A history of CoNS culture positivity in the past month, total parenteral nutrition, and antifungal prophylaxis increases the risk of NAC candidemia.