Multiple organ dysfunction syndrome and death secondary to Cyberlindnera fabianii

Spectrum and management of rare Candida/yeast infections in Kuwait in the Middle East

Invasive fungal infections (IFIs) are associated with high mortality rates and mostly affect patients with compromised immunity. The incidence of IFIs is increasing worldwide with the expanding population of susceptible patients. Candida and other yeast infections represent a major component of IFIs. Rare Candida/yeast infections have also increased in recent years and pose considerable diagnostic and management challenges as they are not easily recognized by routine phenotypic characteristic-based diagnostic methods and/or by the automated yeast identification systems. Rare Candida/yeasts also exhibit reduced susceptibility to antifungal drugs making proper management of invasive infections challenging. Here, we review the diagnosis and management of 60 cases of rare Candida/yeast IFIs described so far in Kuwait, an Arabian Gulf country in the Middle East. Interestingly, majority (34 of 60, 56.7%) of these rare Candida/yeast invasive infections occurred among neonates or premature, very-low-birth-weight neonates, usually following prior bacteremia episodes. The clinical details, treatment given, and outcome were available for 28 of 34 neonates. The crude mortality rate among these neonates was 32.2% as 19 of 28 (67.8%) survived the infection and were discharged in healthy condition, likely due to accurate diagnosis and frequent use of combination therapy. Physicians treating patients with extended stay under intensive care, on mechanical ventilation, receiving broad spectrum antibiotics and with gastrointestinal surgery/complications should proactively investigate IFIs. Timely diagnosis and early antifungal treatment are essential to decrease mortality. Understanding the epidemiology and spectrum of rare Candida/yeast invasive infections in different geographical regions, their susceptibility profiles and management will help to devise novel diagnostic and treatment approaches and formulate guidelines for improved patient outcome.

Identification, molecular characterization, and antifungal susceptibility of Cyberlindnera fabianii strains isolated from urinary tract

OBJECTIVES

Cyberlindnera fabianii is an opportunistic pathogen isolated from clinical specimens. It can be incorrectly identified as Candida utulis by phenotypic methods. This study aimed to accurately identify Cy.fabianii strains isolated from the urinary tract, and to determine their molecular characterization and antifungal susceptibilities as well.

METHODS

Twenty-nine yeast strains isolated from urinary tract samples were studied. Strains were identified by phenotypically, sequence analysis and MALDI-TOF MS. Sequence analysis using different gene regions (ITS1-2,D1/D2,EF-1-alpha) in ribosomal DNA was performed for the molecular analysis. Phylogenetic analysis was done by the neighbor-joining method. Antifungal susceptibilities of strains were determined for nine antifungals by reference broth microdilution and the Sensititre YeastOne broth microdilution method (SensititreTMYeastOneTMAST Plate, Thermo Fisher Scientific™,USA) according to CLSI M60-Ed2 recommendations.

RESULTS

All strains were identified as C.utulis phenotypically by conventional methods, however all strains were identified as Cy.fabianii by sequence analysis and MALDI-TOF MS. It was observed that the gene regions examined in terms of determining evolutionary relatedness did not show intraspecies nucleotide variations. In all strains, the MIC50/MIC90 values for fluconazole were higher than the other antifungals tested.

CONCLUSION

Cy.fabianii should be considered in fluconazole-resistant urinary tract yeast infections. Although conventional phenotypical methods were insufficient to identify Cy.fabianii, it could be correctly identified with sequence analysis using different gene regions (ITS1-2,D1/D2,EF-1-alpha) in ribosomal DNA and MALDI-TOF MS.

A case of prosthetic joint infection due to the rare opportunist yeast, Cyberlindnera fabianii

Background and Purpose

Invasive fungal infections caused by Cyberlindnera fabianii (Cy. fabianii) have recently increased despite the low virulence potential of this yeast. However, limited information about the widely-used commercial biochemical identification systems has led to an underestimation of Cy. fabianii infections in clinical settings.

Case report

This study reports a case of prosthetic joint infection in a patient who had a previous history of total knee replacement surgery. Cy. fabianii was recovered from intraoperative culture specimens identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed using molecular assays. It was, however, initially misidentified as Candida utilis by phenotypic identification.

Conclusion

Due to the emergence of uncommon yeast species, it is important to accurately identify and perform antifungal susceptibility testing on uncommon yeast isolates for appropriate management.

The In Vitro Activity of Fluconazole, Amphotericin B and Echinocandins Against Cyberlindnera fabianii Planktonic Cells and Biofilms

Until recently, little was known about the susceptibility pattern of Cyberlindnera fabianii (Cy. fabianii) planktonic cells and biofilms regarding the most frequently administered systemic antifungals, despite the high mortality rate and its potential role in catheter-related infections. In the current study, the activity of fluconazole, amphotericin B and echinocandins (anidulafungin, caspofungin and micafungin) was determined against planktonic and sessile cells of Cy. fabianii clinical isolates (n = 8). Planktonic minimum inhibitory concentrations (MICs) ranged from 1 to 2, from 0.25 to 1, from 0.015 to 0.06, from 0.03 to 0.12 and from 0.25 to 0.5 mg/l for fluconazole, amphotericin B, anidulafungin, caspofungin and micafungin, respectively. One-day-old biofilms were highly resistant to fluconazole (MIC ranged from 512 to > 512) compared to planktonic counterparts, but not to amphotericin B (MIC ranged from 0.25 to 2 mg/l) and echinocandins (MIC ranged from 0.06 to 2 mg/l). Based on the calculated planktonic killing rates, the highest activity was observed in the case of anidulafungin (k values ranged from 0.37 to 2.09), while micafungin, caspofungin, amphotericin B and fluconazole exerted 0.46–1.47, 0.14–0.86, −0.03 to 2.08 and −0.15 to 0.09 killing rate value ranges, respectively. The obtained in vitro planktonic and sessile susceptibility patterns suggest that echinocandins and amphotericin B may be the most reliable treatment option for the treatment of Cy. fabianii infections.

The Flo Adhesin Family

The first step in the infection of fungal pathogens in humans is the adhesion of the pathogen to host tissue cells or abiotic surfaces such as catheters and implants. One of the main players involved in this are the expressed cell wall adhesins. Here, we review the Flo adhesin family and their involvement in the adhesion of these yeasts during human infections. Firstly, we redefined the Flo adhesin family based on the domain architectures that are present in the Flo adhesins and their functions, and set up a new classification of Flo adhesins. Next, the structure, function, and adhesion mechanisms of the Flo adhesins whose structure has been solved are discussed in detail. Finally, we identified from Pfam database datamining yeasts that could express Flo adhesins and are encountered in human infections and their adhesin architectures. These yeasts are discussed in relation to their adhesion characteristics and involvement in infections.

Rare Invasive Yeast Infections in Greek Neonates and Children, a Retrospective 12-Year Study

Although Candida species remain the leading cause of invasive fungal infections (IFI), the list of other isolated fungal pathogens is increasing. The aim of the study was to report cases of IFI caused by rare yeasts in the largest tertiary Greek pediatric hospital. A retrospective study was performed from 6/2008–6/2020 regarding IFI caused by rare species. Identification of isolates was attained by conventional, molecular, and MALDI TOF MS methods, and susceptibility testing was performed according to the Clinical and Laboratory Standards (CLSI) methodology. During a 12-year period, 14 different rare fungal species in 33 neonates and children with IFI hospitalized in intensive care and oncology units were isolated from blood, central catheters, peritoneal, pleural, or pericardial fluid specimens. It is the first time for IFI caused by Wickerhamomyces anomalus (Candida pelliculosa), Pichia fermentans (Candida lambica), Yarrowia (Candida) lipolytica, Pichia (Hansenula) kluyveri, Rhodotorula mucilaginosa, Wickerhamiella (Candida) pararugosa and Cyberlindnera (Candida) fabianii in Greek neonates and children to be reported. For most of these rare fungal species isolated in the present study, no official antifungal breakpoints have been defined, and there are no guidelines for their treatment. Clinical laboratories should be aware of uncommon and emerging yeast pathogens and be able to detect them with molecular and proteomic methods.