Dynamics of fungal colonization in a new medical mycology laboratory

Can Aspergillus fumigatus conidia cause false-positive results in the galactomannan enzyme immunoassay test?

INTRODUCTION

Several factors can cause false-positive results in the galactomannan (GM) test; however, others remain unknown. Presently, the impact of airborne contamination by Aspergillus conidia during enzyme-linked immunosorbent assay (ELISA) remains uninvestigated.

METHODS

We studied 12 A. fumigatus isolates. Fungal conidia were serially diluted and tested for GM detection using the Platelia® Aspergillus enzyme immunoassay (EIA).

RESULTS

The conidia concentration required for an EIA-positive result was 4.8 × 103 (median).

CONCLUSIONS

This is the first study to evaluate the impact of environmental contamination on the Platelia® Aspergillus EIA assay. Only massive contamination can interfere with GM optical readings, suggesting that environmental contamination does not cause false-positive test results.

Successful treatment of pulmonary invasive fungal infection by Penicillium non-marneffei in lymphoblastic lymphoma: case report and literature review

Penicillium non-marneffei species rarely cause disease in humans and are encountered most commonly in the clinical laboratory as culture contaminants; however, recently they have emerged as opportunistic pathogens in immunocompromised hosts; therefore, it should not be routinely disregarded without a thorough investigation, especially if normally sterile sites are involved.

Production of an extracellular matrix as an isotropic growth phase of Penicillium rubens on gypsum

Indoor mold represents an important environmental concern, but a fundamental knowledge of fungal growth stages is needed to limit indoor fungal proliferation on finishing materials used in buildings. The present study focused on the succession of germination stages of the common indoor fungus Penicillium rubens on a gypsum substrate. This substrate is used as a model system representing porous materials that are widely used in indoor environments. Imaging with cryo-scanning electron microscopy showed that the formation of an extracellular matrix (ECM) is a phase of the isotropic growth of P. rubens that is uniquely related to germinating conidia. Furthermore, the ECM is observed only when a dry-state inoculation of the surface is applied, i.e., applying conidia directly from a 7-day-old colony, mimicking airborne contamination of the surface. When inoculation is done by spraying an aqueous conidial suspension, no ECM is observed. Moreover, it is concluded that the formation of an ECM requires active processes in the fungal cell. The porosity of the substrate proved that the ECM substance has high-viscosity characteristics. The present results stress that studies of indoor fungal growth should consider the method of inoculation, knowing that the common aqueous suspension may obscure specific stages in the initial phases of germination.