Bloodstream infection caused by Wickerhamiella pararugosa in a patient with intestinal obstruction: A case report

The fungus Wickerhamiella pararugosa (Candida pararugosa) has been detected in various human organs but has rarely caused bloodstream infections. This report presents a case of central venous catheter-related bloodstream infection (CRBSI) of W. pararugosa in an adult. A female patient in her 80s was admitted to our facility for intestinal obstruction caused by colorectal cancer. The patient's ability to consume food was hindered, necessitating the insertion of a central venous catheter (CVC) into the internal jugular vein. On day 3 after admission, the patient developed a fever, prompting blood and CVC tip cultures to be performed. On day 5, yeast-like fungi were discovered in the blood cultures, and fosfluconazole (fluconazole [FLCZ] pro-drug) treatment was initiated. On day 8, yeast-like fungi were identified in both the blood and CVC tip cultures, leading to a diagnosis of CRBSI. The fungus was identified as W. pararugosa through biochemical and genetic characterization. This finding justified the use of micafungin (MCFG) for combination therapy. On day 17, the minimum inhibitory concentrations (MIC) for FLCZ and MCFG were 4-8 and 0.06 μg/mL, respectively. Accordingly, the treatment was changed to monotherapy with MCFG. After a 21-day treatment regimen, the patient was discharged on day 31. We present a case of CRBSI caused by W. pararugosa in an adult with intestinal obstruction. The notable increase in the MIC of FLCZ necessitated monotherapy with MCFG, which resulted in successful recovery of the patient.

Characterization of Yeasts Isolated from Parmigiano Reggiano Cheese Natural Whey Starter: From Spoilage Agents to Potential Cell Factories for Whey Valorization

Whey is the main byproduct of the dairy industry and contains sugars (lactose) and proteins (especially serum proteins and, at lesser extent, residual caseins), which can be valorized by the fermentative action of yeasts. In the present study, we characterized the spoilage yeast population inhabiting natural whey starter (NWS), the undefined starter culture of thermophilic lactic acid bacteria used in Parmigiano Reggiano (PR) cheesemaking, and evaluated thermotolerance, mating type, and the aptitude to produce ethanol and bioactive peptides from whey lactose and proteins, respectively, in a selected pool of strains. PCR-RFLP assay of ribosomal ITS regions and phylogenetic analysis of 26S rDNA D1/D2 domains showed that PR NWS yeast population consists of the well-documented Kluyveromyces marxianus, as well as of other species (Saccharomyces cerevisiae, Wickerhamiella pararugosa, and Torulaspora delbrueckii), with multiple biotypes scored within each species as demonstrated by (GTG)₅-based MSP-PCR. Haploid and diploid K. marxianus strains were identified through MAT genotyping, while thermotolerance assay allowed the selection of strains suitable to grow up to 48 °C. In whey fermentation trials, one thermotolerant strain was suitable to release ethanol with a fermentation efficiency of 86.5%, while another candidate was able to produce the highest amounts of both ethanol and bioactive peptides with potentially anti-hypertensive function. The present work demonstrated that PR NWS is a reservoir of ethanol and bioactive peptides producer yeasts, which can be exploited to valorize whey, in agreement with the principles of circularity and sustainability.