Genetic and biological features of catheter-associatedMalassezia furfurfrom hospitalized adults

Abstract

Malassezia furfur, an etiological agent of catheter-associated fungemia, requires long-chain fatty acids for in vitro growth. We examined the applicability of rDNA sequence analysis, autoaggregation testing in liquid culture, utilization of parenteral lipid emulsions, and phospholipase activity for discrimination of catheter-associated M. furfur strains. The rDNA sequence types of catheter-associated M. furfur strains were distinct from those of other isolates. All M. furfur isolates recovered from blood culture bottles and the tips of catheters from patients receiving fat emulsion therapy were type I-3. Only M. furfur isolate GIFU 01 from a blood culture bottle showed no autoaggregation in liquid culture. All strains of M. furfur examined grew well on Sabouraud's dextrose agar supplemented with Intralipid lipid emulsion as compared to individual Tweens (20, 40, 60, 80) and Cremophor EL. A high percentage of type I-3 M. furfur strains (80.0%) showed very high phospholipase activity compared to type I-1 and I-4 strains obtained from healthy skin of the same subjects or healthy control subjects (20.0% and 0.0%, respectively). The blood culture bottle isolate GIFU 01 showed very high lipolytic enzymes activity for Intralipid but no phospholipase activity. These results suggest that particular factors, such as non-autoaggregation and very high lipolytic enzyme activity for parenteral lipid emulsions, play important roles in the growth and pathogenicity of Malassezia-related sepsis.

Malassezia infections with systemic involvement: Figures and facts

“…Concerning the causative species, the presented data on Malassezia bloodstream infection isolates are in accordance with the findings of previous epidemiological surveys, unveiling M. furfur as the most common culprit agent . The occurrence of three cases of confirmed M. furfur bloodstream infection in a tertiary care hospital during a 2‐year period is consistent with the reported low prevalence of these invasive infections, usually confined to severely immunocompromised hosts .…”

The Malassezia Genus in Skin and Systemic Diseases

“…However, conventional culture and identification methods offer the advantage of further evaluating the isolates for possible virulence factors, such as the production of phospholipase (44,170) and indole (108,184,336) and melanin synthesis (107). Furthermore, this was highlighted in a study by Akaza et al (6), in which the seasonal rates of isolation of Malassezia species from healthy skin determined by quantitative PCR (qPCR) were compared with those determined by use of Leeming-Notman agar (197).…”

“…The poor response to amphotericin B (112), is currently supported by the in vitro-recorded high MIC values of this agent (320). Recent data showed that the M. furfur strains that have the ability to cause systemic infections belong to a distinct internal transcribed spacer 1 group and demonstrate increased phospholipase activity (170).…”

“…Molecular typing of Malassezia yeasts. Current data (Table 8) point toward the existence of pathogenic subtypes of M. furfur (113,170,350), M. globosa (112,307), and M. restricta (296,307). The Malassezia microbiota was suggested to be host specific (243).…”

Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates

“…Microscopic examination of clinical samples and colonies shows that small ovoid, ellipsoidal, or cylindrical blastoconidia (1.1 to 2.5 μm by 1.7 to 2.7 μm) with a large-base bud are characteristic of the genus Malassezia (2). Classical species identification comprises both biochemical and morphological studies, but this is rarely done due to the difficulty of interpreting lipophilic tests and the morphological closeness of the different species (16–18). Insufficiency of species identification contributes to the lack of epidemiological knowledge about Malassezia infections.…”