Rapid detection of biofilm-producing Candida species via MALDI-TOF mass spectrometry

AIMS

The aim of this study was to evaluate the formation of biofilm by Candida spp. isolated from the bloodstream, using traditional spectrophotometric methodologies. In addition, the goal was to compare the results with those obtained through MALDI-TOF/MS, as well as to verify its use as a potential tool for the detection of biofilm-forming strains.

METHODS AND RESULTS

Hundred and thirteen isolates of Candida spp. were studied: 41 were Candida albicans, 27 C. tropicalis, 18 C. glabrata, 17 C. parapsilosis and 10 C. krusei. Metabolic activity was determined through the tetrazolium salt (XTT) reduction assay and biomass by staining with Crystal Violet. All isolates were able to form biofilm, 94% of which were strong producers, with high biomass quantification (95%; 107/113) and high metabolic activity (99%; 112/113). Mass spectra of the biofilm-producing isolates showed differences in the intensity of mass peaks when compared with the spectra of the nonproducing strains.

CONCLUSIONS

It was demonstrated that MALDI-TOF/MS was able to detect specific biofilm proteins, as the mass spectra of the isolates presented differences when compared with nonproducing strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

MALDI-TOF/MS can become a valuable tool for biofilm detection at the moment of the identification of the microorganism, thus contributing greatly to the management of patients with Candidemia.

Isolation of Cryptococcus species from the external environments of hospital and academic areas

INTRODUCTION

Fungi of the genus Cryptococcus are cosmopolitan and may be agents of opportunistic mycoses in immunocompromised and sometimes immunocompetent individuals. Cryptococcus species are frequently isolated from trees and bird excreta in the environment and infection occurs by inhalation of propagules dispersed in the air. The aim was to investigate Cryptococcus species in bird excreta and tree hollows located in a university hospital area and in an academic area of a university campus.

METHODOLOGY

A total of 40 samples of bird excreta and 41 samples of tree hollows were collected. The identification of the isolates was done by classical methodology and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

Twenty (62.5%) isolates of Cryptococcus were found in bird excreta and 12 (37.5%) in tree hollows. C. laurentii (currently Papiliotrema laurentii) was the most frequent species in both samples, being found in 5 samples of excreta and in 8 tree hollows. The diversity of species found in excreta (C. laurentii, C. albidus [currently Naganishia albida], C. liquefaciens [currently N. liquefaciens], C. friedmanii [currently N. friedmannii] and others) was higher than in tree hollows (C. laurentii, C. flavescens [currently Papiliotrema flavescens], and other yeasts).

CONCLUSION

Many Cryptococcus species were isolated from excreta and tree hollows, and this fact is important for understanding the environmental epidemiology of those emerging pathogens for public health, as a way to implement surveillance actions and control of cryptococcosis.