We present a 19-year-old female, eight weeks postpartum, with a seven-week history of migratory arthralgias followed by progressive dyspnea and pleuritic chest pain. A large mass in her right lower lobe was discovered on computed tomography. Laboratory evaluation demonstrated elevated anti-proteinase 3 (PR3) antibody, along with elevated inflammatory markers. The bronchoalveolar lavage culture grew Cryptococcus neoformans, and serum cryptococcal antigen was positive. The patient was diagnosed with pulmonary cryptococcosis and treated with amphotericin and flucytosine, given the severity of her illness. Granulomatosis with polyangiitis was a part of the initial differential but was not diagnosed until she later developed transient hemoptysis, recurrent epistaxis, skin rash, and significant proteinuria. The skin biopsy was consistent with cutaneous vasculitis, and the kidney biopsy was positive for glomerulonephritis, confirming postpartum systemic vasculitis masked by a concurrent pulmonary cryptococcal infection.

Primary cutaneous cryptococcosis (PCC) is acquired through direct inoculation of Cryptococcus neoformans into wounds or damaged skin, typically resulting in a localized infection confined to a single cutaneous site. Progression of PCC to disseminated cryptococcosis is extremely rare. The purpose of this case report is to describe an unusual instance of PCC progressing into disseminated disease in an immunosuppressed older patient and to highlight the importance of considering cryptococcosis as a differential diagnosis of cutaneous lesions unresponsive to antimicrobial therapy. We report the case of an 88-year-old woman with Evans syndrome receiving oral prednisolone (17.5 mg/day) who also had diabetes mellitus and engaged in home gardening. She developed redness, swelling, and induration of the right forearm 18 days before admission and was treated with cefazolin for presumed cellulitis. Subsequently, yeast-like fungi were detected from the wound and blood cultures on hospital day 7, and C. neoformans was identified on hospital day 8, leading to the diagnosis of disseminated cryptococcosis. Antifungal therapy with amphotericin B (150 mg/day) and flucytosine (2.5 mg/day) was initiated the same day. C. neoformans was later isolated from cerebrospinal fluid. Despite antifungal treatment, her condition progressively deteriorated, and she died. This case illustrates an exceptionally rare progression of PCC to disseminated disease in an older immunosuppressed patient. It highlights the need for heightened clinical suspicion of cryptococcosis when cutaneous lesions fail to respond to antimicrobial therapy, particularly in individuals receiving corticosteroids or with additional risk factors such as diabetes or soil exposure. Early recognition and appropriate antifungal management are essential to prevent fatal outcomes.

In prodrug-activated gene therapy (PAGT), a prodrug is converted into a cytotoxic metabolite only in cells transduced with viral or bacterial genes. Recent studies have explored the combined use of cytosine deaminase/5-flucytosine (CD/5-FC) and herpes simplex virus-derived thymidine kinase/ganciclovir (HSV-TK/GCV) PAGT systems to enhance anticancer efficacy. This study aimed to develop a simultaneous analytical method for 5-FC, GCV, and valganciclovir (VGC), the prodrug of GCV, using LC-MS/MS and to investigate the pharmacokinetic differences following their coadministration in Sprague-Dawley (SD) rats. The developed simultaneous analytical method met FDA guidelines and demonstrated good reproducibility and reliability. Using this method, the pharmacokinetic characteristics of the three compounds (5-FC, GCV, and VGC) were assessed in SD rats. Following intravenous and oral administration of VGC, 61.44% of VGC converted to GCV, and the bioavailability of GCV improved from 9.78% to 61.38%. In vitro studies were conducted to evaluate the metabolic pathways and conversion rates. Slow elimination of VGC in the microsomes and plasma suggests that its primary metabolic pathway is not mediated by cytochrome P450 enzymes or plasma esterases. Although certain pharmacokinetic parameters differed between the single and coadministration groups, the differences in the maximum plasma concentration (Cmax) were small, and no significant differences were observed in area under the plasma concentration-time curve (AUC). Considering that renal excretion is the major elimination pathway for both 5-FC and GCV, the extent of drug-drug interactions appears to be minimal, suggesting that their established maximum doses can be applied without safety concerns. Our study results may provide a basis for future studies on drug-drug interactions and dosage optimization.

Although supernumerary ribs have been examined in regulatory developmental toxicity studies, their toxicological significance remains controversial because of the unclear etiology and strain-dependent background incidence of this condition. In the current study, we established a rat model of drug-induced supernumerary ribs by administering flucytosine to pregnant Sprague-Dawley rats, a strain with low natural occurrence of this skeletal anomaly. The results revealed that flucytosine exposure induced supernumerary ribs in a dose- and timing-dependent manner, accompanied by dysregulated expression of specific Hox genes. Altered expression was correlated with axial patterning defects and, in some cases, limb abnormalities. Comparative genetic analysis between Sprague-Dawley rats and BrlHan:WIST@GALAS rats, which exhibit high spontaneous incidence (~50%) of supernumerary ribs, revealed sequence variation in the upstream regulatory region of Hoxa9, particularly affecting miR-196b. These findings demonstrate that temporal dysregulation of Hox gene networks and micro RNA (miRNA)-mediated modulation are key factors in the pathogenesis of supernumerary ribs. Moreover, our results suggest that genetic background should be considered when interpreting skeletal variations in developmental toxicity studies. Mechanistic understanding of these findings may improve the relevance of endpoints in risk assessment and regulatory decision-making.

Cryptococcus neoformans causes serious infections of the central nervous system, including meningitis, encephalitis, or cryptococcomas, and is increasingly reported in immunocompetent individuals. Cryptococcal choroid plexitis is a rare entity that often presents with ependymitis and synechiae formation, resulting in "trapped ventricles." Cryptococcomas forming gelatinous pseudocysts manifest as prominent Virchow-Robin spaces and lead to false-negative smear and culture reports, leading to a delay in diagnosis. We report a 37-year-old woman from Assam with chronic headache for 3 months, recurrent seizures, and altered mentation for 15 days. Contrast-enhanced magnetic resonance imaging showed features of choroid plexitis and obstructive hydrocephalus with "trapped" temporal horns of the ventricle. Serum and cerebrospinal fluid cryptococcal antigen were weakly positive, with negative fungal smear and cultures. She was treated with liposomal amphotericin B with flucytosine but developed brainstem herniation and died. Autopsy of the brain revealed bulky choroid plexus with prominent Virchow-Robin spaces and gelatinous pseudocysts. Microscopic examination revealed multiple periventricular microabscesses teeming with cryptococcal organisms. The case, along with a systematic review of similar cases in the literature, highlights the complexities in diagnosing and managing cryptococcal meningoencephalitis in the immunocompetent host.

Cryptococcal meningitis (CM) is a severe opportunistic infection in people living with HIV (PLWH). We report a 54-year-old man with advanced HIV infection who presented with CM due to Cryptococcus neoformans. Induction therapy with liposomal amphotericin B (4 mg/kg/day) plus fluconazole (800 mg/day) was prolonged to 10 weeks because flucytosine was initially unavailable; intravenous flucytosine (25 mg/kg q6h) was introduced when accessible. Maintenance fluconazole (800 mg/day) was continued, and antiretroviral therapy (ART) with dolutegravir plus emtricitabine/tenofovir disoproxil was initiated after 8 weeks. One year later, despite virological suppression, he developed neurological deterioration compatible with recurrent CM in the absence of culture confirmation. He underwent re-induction with liposomal amphotericin B plus flucytosine, followed by off-label secondary prophylaxis with oral isavuconazole (200 mg/day). Over 6 months, he maintained HIV-RNA suppression, showed CD4+ T-cell recovery (from 94 to 165 cells/mm[3]), and experienced neurological stabilization without further CM episodes or drug-related toxicity. Isavuconazole's pharmacokinetic profile, oral availability, and limited antiretroviral drug-drug interactions supported its use as extended secondary prophylaxis in this setting, although limited access in low- and middle-income countries remains a concern. This case highlights isavuconazole as a potential alternative prophylactic strategy when fluconazole is ineffective or not tolerated.

Candida auris is an emerging pathogen known for causing invasive, multidrug-resistant infections and healthcare-associated outbreaks. Measuring the relatedness of C. auris strains is critical for detecting and preventing healthcare-associated transmission. Whole genome sequencing (WGS) and analysis of single-nucleotide polymorphisms (SNPs) offer high-resolution assessments of genetic relatedness and antifungal susceptibility; however, interpretation requires an understanding of inter- and intra-patient C. auris diversity and genotypic markers of resistance, respectively. This study aimed to define SNP thresholds for assessing C. auris relatedness in healthcare-associated outbreak investigations, predict antifungal resistance via genotypic markers, and evaluate patient risk factors to inform future surveillance strategies. WGS was performed on 68 C. auris isolates (clades I and III) obtained from 31 hospitalized patients across a healthcare system between 2021 and 2024. Using MycoSNP analysis, we observed a maximum intra-patient variation of 14 SNPs. Five probable transmission clusters were identified based on epidemiologic links, with patient isolates differing by a median of 5 SNPs (range: 0-12). Analysis with a commercial pipeline (refMLST, BugSeq) showed similar clustering patterns. All new detections occurring more than 1 month after admission were linked to a cluster, representing a highly specific indicator of healthcare-associated infection. WGS detected known genotypic markers for fluconazole (ERG11 Y132F, F126L, and MRR1 N647T) and micafungin (FKS1 F635C) resistance, with the latter emerging during antimicrobial therapy. In addition, putative FUR1 mutations (G207R and Q16::STOP) associated with flucytosine resistance were identified. These findings emphasize the utility of WGS for identifying healthcare-associated clusters of C. auris and predicting antifungal resistance.IMPORTANCECandida auris is a difficult-to-treat yeast that causes invasive infections in vulnerable patient populations. Healthcare exposure is a key risk factor for becoming colonized or infected with C. auris, and infection prevention groups focus on curbing the spread of this organism within the healthcare environment. Whole genome sequencing approaches are key for supporting these efforts, as they can help define clusters of C. auris transmission and can also provide insight into antifungal resistance. Our work provides practical guidance for interpreting genomic data in this setting, helping infection prevention teams respond more effectively to outbreaks and expanding the use of genotypic predictions for antifungal resistance.

Cryptococcus neoformans is an encapsulated yeast that typically causes cryptococcal meningitis (CM) in immunocompromised hosts. However, CM can rarely occur in immunocompetent individuals, often with atypical or insidious presentations. Persistently positive cerebrospinal fluid (CSF) cultures despite guideline-directed antifungal therapy are uncommon and pose significant management challenges. In this case report, we describe a previously healthy 40-year-old immunocompetent woman who presented with seizures, progressive headaches, and elevated intracranial pressure (ICP). CSF studies confirmed CM with positive cryptococcal antigen and cultures. She was treated with liposomal amphotericin B and flucytosine and later transitioned to high-dose fluconazole due to medication intolerance. Despite >6 weeks of antifungal therapy, serial CSF cultures remained persistently positive through hospital day 56, with clearance achieved only on day 72. ICP management required serial lumbar punctures, temporary lumbar drainage, and ultimately ventriculoperitoneal (VP) shunt placement on day 80. The patient was discharged on prolonged fluconazole consolidation therapy with resolution of headaches but residual right-eye visual deficits. This case highlights the potential for CM in immunocompetent hosts with protracted culture positivity despite guideline-directed antifungal therapy. Early recognition of antifungal intolerance, aggressive ICP management, and timely surgical intervention may be critical for optimizing outcomes in such complex cases.

Disseminated cryptococcosis, particularly cryptococcal meningitis, remains a severe fungal infection with high mortality in immunocompromised patients and usually requires prolonged azole therapy. In kidney transplant recipients receiving tacrolimus (TAC), careful management of drug-drug interactions via CYP3A is essential to maintain stable blood concentrations. We report the case of a 44-year-old man with a history of focal segmental glomerulosclerosis who had undergone a living-donor kidney transplant three years earlier. He was receiving immunosuppressive therapy with TAC, mycophenolate mofetil, and methylprednisolone. The patient developed cryptococcal meningitis and skin and soft tissue infection due to Cryptococcus neoformans, together with probable invasive aspergillosis of the paranasal sinuses. He received induction therapy with liposomal amphotericin B and flucytosine for approximately 10 weeks, but persistent intracranial hypertension required placement of a ventriculoperitoneal shunt. Consolidation and maintenance therapy with isavuconazole (ISCZ) was then initiated and has been continued successfully for more than 12 months, without adverse events and with stable TAC concentrations. At the time of writing, the treatment duration has exceeded 365 days, and he remains under outpatient management with no signs of recurrence. To our knowledge, reports describing more than 12 months of ISCZ therapy for cryptococcal infection are limited. This case highlights its potential as a maintenance option in transplant recipients, particularly when fluconazole or voriconazole are not suitable due to drug-drug interactions with TAC.

Candida auris has garnered substantial clinical and public health attention for its widespread antifungal resistance. Most isolates are resistant to fluconazole, and many, to other drug classes, with acquired resistance to all clinically available antifungal drugs reported. Antifungal resistance is rising alongside increasing case counts, threatening a sparse antifungal toolbox with multidrug and pan-resistant isolates that may cause untreatable infections. In this minireview, we examine the recent literature investigating the mechanisms and evolutionary patterns of resistance in clinical isolates of C. auris to each antifungal utilized to combat these infections. We propose a refined model of C. auris drug resistance by separating the multidrug resistance paradigm into distinct resistance challenges for each drug class. We examine how the emergence of unique resistance patterns to each drug may suggest therapeutic options even for currently available antifungals. Resistance to fluconazole is driven by drug target mutations with clade-specific representation and more diverse acquired mutations in drug efflux regulators. Recent structural insights into the context of these mutations may suggest vulnerabilities to other triazoles even in fluconazole-resistant strains. Acquired resistance to echinocandins, amphotericin B, and the pyrimidine analog flucytosine is rare but can emerge under antifungal therapy through conserved resistance mechanisms. The reportedly higher amphotericin B resistance rate in C. auris relative to other Candida species remains poorly understood and may be linked to unexplored intrinsic resistance mechanisms. We suggest that close examination and further investigation of these mechanisms may inform better therapeutic practice and may offer treatment solutions for this multidrug-resistant pathogen.

Invasive infections due to Magnusiomyces/Saprochaete species are an emerging problem in immunocompromised patients and are often underrecognized because of misidentification and intrinsic resistance to some antifungals. This multicenter study investigated the species distribution, antifungal susceptibility patterns, and key virulence traits of clinical isolates from Türkiye. A total of 133 clinical isolates collected between 2010 and 2024 from 18 hospitals in 10 cities were identified by MALDI-TOF MS and ITS/LSU sequencing. MICs of amphotericin B, fluconazole, voriconazole, itraconazole, posaconazole, and flucytosine were determined using the EUCAST broth microdilution method. Biofilm formation and esterase, caseinase, secreted aspartyl proteinase, phospholipase, and hemolysin activities were assessed phenotypically. Sequencing identified 107 isolates (80.4%) as Magnusiomyces capitatus and 26 (19.6%) as Magnusiomyces clavatus, MALDI-TOF MS identified 106 (79.7%) as M. capitatus and 27 isolates (20.3%) as M. clavatus. There was 99.2% agreement between MALDI-TOF MS and sequencing results. Voriconazole, amphotericin B, and posaconazole showed the lowest MICs, whereas fluconazole displayed wide MIC ranges and limited activity. Overall, 97.7% of isolates were strong biofilm producers, with significantly higher biofilm production in M. capitatus. In contrast, M. clavatus showed higher caseinase and esterase activity. This study provides the most extensive multicenter dataset on Magnusiomyces/Saprochaete in Türkiye and underscores their considerable pathogenic potential through strong biofilm formation and tissue-degrading enzyme activities. Accurate species-level identification using MALDI-TOF MS supported by molecular methods is essential, and limited fluconazole activity suggests that voriconazole and amphotericin B should be prioritized in species-guided treatment strategies.

Fungal mastitis is rare but poses a significant problem for dairy farmers. It is often underestimated and under-researched, with most studies and treatments focusing on bacterial infections. Antibiotics are ineffective against fungi, and they exacerbate fungal mastitis. This study aimed to determine the antifungal properties of silver (Ag), gold (Au), copper (Cu), iron with a hydrophilic carbon coating (FeC), and platinum (Pt) nanoparticles (NPs) at five different concentrations, as well as their complexes, on the survival of fungal strains such as Pichia kudriavzevii, Wickerhamiella pararugosa, Saccharomyces cerevisiae, Cutaneotrichosporon mucoides, Wickerhamomyces anomalus, Coniochaeta hoffmannii, and Kluyveromyces marxianus. The strains' susceptibility to 8 standard antifungals, along with MIC (minimal inhibitory concentration) and MFC (minimal fungicidal concentration) after NP treatment, was assessed. Clotrimazole and ketoconazole (10 µg) were most effective, while fluconazole (10 µg) and flucytosine (1 µg) showed the weakest activity. The AgCuNP complex demonstrated the strongest biocidal activity against all isolated strains, while FeCNPs and PtNPs showed very weak or no biocidal properties. The study's results provide a basis for further in vivo research, indicating the great potential of nanoparticles in combating fungal mastitis, providing an innovative solution against infections caused by drug-resistant pathogens.