Techniques for the detection of pathogenic Cryptococcus species in wood decay substrata and the evaluation of viability in stored samples
Mem. Inst. Oswaldo Cruz
;
108(1): 126-129, Feb. 2013. tab
Article
in English
| LILACS
| ID: lil-666058
ABSTRACT
In this study, we evaluated several techniques for the detection of the yeast form of Cryptococcus in decaying wood and measured the viability of these fungi in environmental samples stored in the laboratory. Samples were collected from a tree known to be positive for Cryptococcus and were each inoculated on 10 Niger seed agar (NSA) plates. The conventional technique (CT) yielded a greater number of positive samples and indicated a higher fungal density [in colony forming units per gram of wood (CFU.g-1)] compared to the humid swab technique (ST). However, the difference in positive and false negative results between the CT-ST was not significant. The threshold of detection for the CT was 0.05.10³ CFU.g-1, while the threshold for the ST was greater than 0.1.10³ CFU-1. No colonies were recovered using the dry swab technique. We also determined the viability of Cryptococcus in wood samples stored for 45 days at 25ºC using the CT and ST and found that samples not only continued to yield a positive response, but also exhibited an increase in CFU.g-1, suggesting that Cryptococcus is able to grow in stored environmental samples. The ST.1, in which samples collected with swabs were immediately plated on NSA medium, was more efficient and less laborious than either the CT or ST and required approximately 10 min to perform; however, additional studies are needed to validate this technique.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Specimen Handling
/
Wood
/
Cryptococcus neoformans
/
Microbial Viability
/
Cryptococcus gattii
Type of study:
Diagnostic study
Language:
English
Journal:
Mem. Inst. Oswaldo Cruz
Journal subject:
Tropical Medicine
/
Parasitology
Year:
2013
Type:
Article
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Fiocruz/BR
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