Genetic Variability among Blastoschizomyces Capitatus Isolates from Different Clinical Sources

Saprochaete/Magnusiomyces: identification, virulence factors, and antifungal susceptibility of a challenging rare yeast

Saprochaete/Magnusiomyces is among rare yeasts which might emerge as causes of breakthrough infections and nosocomial outbreaks. Identification to the species level might be a challenge in clinical laboratories. Data on virulence factors are scarce and antifungal susceptibility testing methodology is not definite. The aim of this study was to confirm species identification of clinical Saprochaete/Magnusiomyces isolates, find out their virulence factors, and obtain antifungal minimum inhibitory concentrations with two reference methods. Of the 57 isolates included, 54 were Saprochaete capitata and four were Saprochaete clavata as identified by ID32C, MALDI-TOF MS, and sequencing. When tested using phenotypic methods, all isolates were negative for coagulase, hemolysis, acid proteinase, and phospholipase, 56.1% were positive for esterase, and 19.3% had intermediate surface hydrophobicity. All isolates formed biofilms, with 40.4% of the isolates producing more biomass than biofilm-positive reference strain Candida albicans MYA-274. Antifungal susceptibility testing needed an adjusted spectrophotometric inoculum than recommended in reference methods for Candida/Cryptococcus. In conclusion, Saprochaete/Magnusiomyces species could be identified using methods available in the clinical laboratories. Despite the disadvantages of the phenotypic methods, esterase positivity was observed for the first time. A high biomass production was observed in biofilms. The need for standardization of antifungal susceptibility testing was brought to attention.

Blastoschizomyces capitatus pulmonary infections in immunocompetent patients: case report, case series and literature review

Blastoschizomyces capitatus is an uncommon opportunistic yeast associated with infections in neutropaenic patients secondary to haematological malignancies, with a special predilection for the lungs. Globalisation and population migration impact on the epidemiology of infection with this organism but its effect on the immunocompetent population has rarely been described. We present here a case report, an overview of 11 other cases published between 2000 and 2016, and a comprehensive literature review of Blastoschizomyces pneumonia in the non-immunocompromised. The median age at diagnosis was 68 years (range 40-86 years) and more than half the cases reported a positive history of either current or past tobacco smoking. Six cases had either clinical or radiological evidence of chronic obstructive pulmonary disease and three had a history of prior treated tuberculosis. Fluconazole and itraconazole, alone or in combination, was the most utilised treatment. We conclude that unlike most other invasive yeast species, B. capitatus poses an infectious risk for immunocompetent patients, usually of middle to older age with risk factors for distorted lung architecture. Further research is warranted into the pathophysiology of Blastoschizomyces infections in the immunocompetent, including standardised treatment options.