Abstract
The genetic diversity of 89 clinical Legionella isolates, collected between 1987 and 2012, in 22 hospitals from the five regions of Portugal, was analysed in this study using monoclonal antibodies (MAbs) of the Dresden panel and the sequence-based typing (SBT) protocol. The eBURST algorithm was used to infer levels of relatedness between isolates. All isolates collected were Legionella pneumophila, which were further characterised into four subgroups by MAbs, and 30 sequence types (STs) by SBT. Twelve of the STs were unique to Portugal; one of them (ST100) was represented by 32 epidemiologically related isolates. The ST44 was the profile with the highest number of epidemiologically unrelated isolates. The eBURST analyses indicate that, within the group formed by the 30 STs identified in this study, 17 STs were genetically close to at least another ST in the group. The comparison between the eBURST diagrams obtained with the STs from this study and the entire SBT database of the European Working Group for Legionella, showed that 24 (seven of them unique to Portugal) of our 30 STs were related with STs identified in others countries. These results suggest that the population of L. pneumophila clinical strains in Portugal includes both worldwide and local strains.
Highlights
Legionellaceae are ubiquitous in the environment, being prevalent in man-made habitats, such as cooling towers and domestic hot and cold water distribution systems
Of the 84 sg1 isolates, 83 had the virulence-associated epitope recognised by MAb3/1; belonged to the Philadelphia subgroup, 30 to the Allentown/France, 17 to the Knoxville and three to the Benidorm
In Portugal, like other countries, most of the diagnoses of Legionnaires’ disease (LD) are currently made by antigen detection in urine, due to the simplicity, rapidity and specificity of this test for L. pneumophila sg1
Summary
Legionellaceae are ubiquitous in the environment, being prevalent in man-made habitats, such as cooling towers and domestic hot and cold water distribution systems. This family consists of a single genus, Legionella, but contains 56 species/subspecies belonging to over 70 serogroups [1]. When a case of LD occurs, it is essential that public health authorities are able to detect the source of infection promptly by comparing clinical and environmental isolates, so that decontamination measures can prevent further cases. For this comparison, the sequencebased typing (SBT) scheme and monoclonal antibodies
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