Abstract (EN):
Infections caused by Legionella spp. are considered at the present time, an emerging public health problem and
are linked to high rates of mortality and morbidity, if not properly treated. In this study were analyzed 54 samples of water
from 8 counties at Northern Portugal, with the aim of obtaining a collection of strains of the genus Legionella and to characterize
them genetically and phenotypically. Another objective of this study was to evaluate the effectiveness of the technique
of cultivation, a standard method according to International Organization for Standardization ISO 11731:1998, for
detection and enumeration of species of Legionella. For laboratory processing, after the filtration of samples (1 L), the filtrate
was resuspended in sterile distilled water (5 ml). Heat treatment for selective inhibition of non-Legionella bacteria was
performed. Subsequently, 100 ¿l of the suspension was spread in GVPC selective agar medium, and incubated (7 to 10 days)
at 37 ¿. Colonies that were morphologically characteristic of the genus were sub-cultured onto BCYE agar and blood agar
for verification. According to the procedure recommended by the standard method, only the colonies which grew in BCYE
agar and not on blood agar were considered as suspected Legionella strains. The identification of these initially selected
colonies was performed by sequencing the 16S rRNA gene, which revealed that none of the isolates were identified as belonging
to the genus Legionella. However, through the ISO 11731:1998 they were interpreted as positive, corresponding
therefore to ¿false-positive¿ results. The methods used in this study allowed the isolation of a number of isolates (40), which
form an independent group of all genus of the family Chitinophagaceae outlined so far, and that by their phylogenetic distance
might be a genus not yet described and therefore a new species. The results obtained, highlighted the importance of
using culture and genetic methods in parallel for the proper identification of microorganisms
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
8