Researchers from the Microbiology group at the University of the Balearic Islands (UIB), from the Spanish company biolinethe Rotger Clinic and other European research centers described a new species of legionella bacteria, which they named Legionella Maioricensis.
The new species was isolated for the first time in Mallorca and is the first to be discovered in Spain. The discovery was recently published in the International Journal of Systematic and Evolutionary Microbiology.
The sample was isolated in 2012 by Biolinea. in routine water sampling at a hospital in Mallorca. At that time, it had not yet been identified as a new species, but due to its characteristics it was suspected that it could be a new legionella. Later, it became known that another environmental health laboratory in the Czech Republic had isolated, in another routine sampling carried out in a supermarket, a strain with characteristics similar to that isolated in Mallorca.
Delay in its characterization due to the pandemic
In a first approximation based on the partial sequencing of molecular marker genes for legionella and on several laboratory tests, it was already envisaged that it was a new species. These studies were presented for the first time at a scientific congress in Athens in 2019. The covid-19 pandemic interrupted investigations, until in 2022 the bacterium could be definitively characterized and identified as a new species of this bacterium.
According to Sebastián Crespí, first signatory of the study and scientific director of Biolinea, “as far as we know, there is no evidence that this new species has caused infections in humans, although, at least in theory, it could. “
In fact, the comparative genomic analysis performed in this study revealed the presence of a considerable number of virulence factors in the genome of Legionella Maioricensis. In addition, genetic information was detected that points to its ability to be resistant to certain antibiotics, such as penicillins, cephalosporins or monobactams.
Knowledge of the diversity of bacterial populations contributes to the effort to clarify the gaps that still exist regarding its pathogenic potential.
The discovery of this new species of legionella represents an important advance in the knowledge of the diversity of populations of the bacterium and contributes to the efforts of the scientific community to clarify the gaps that still exist regarding its pathogenic potential.
Antoni Bennàsar, UIB researcher and co-main author of the article, indicates that “knowledge about the population diversity of this bacterium is still limited. Many questions and uncertainties remain unanswered about the epidemiology of legionella, the infectivity of the strain, the infectious dose and the capacity of detection methods, in part limited by the apparent lack of knowledge of the biodiversity of the genus”.
65 species of Legionella described
One of the 65 species of legionella described so far, Legionella pneumophila, is known to be the cause of 90% of cases of legionellosis or legionnaires’ disease, a relatively uncommon respiratory disease that presents as severe pneumonia and threatens life in 10% of cases. In addition, it causes Pontiac fever, a mild non-pneumonic flu-like illness.
The main sources of infection are drinking water systems, bathing water with water and air jets and cooling towers.
The infection is mainly acquired by inhaling bioaerosols, very fine droplets of water contaminated with the bacteria. The main sources of infection are drinking water systems, especially domestic hot water, bathing water with water and air jets and cooling towers, although any system that generates aerosols outside (ornamental fountains, spray irrigation, washing stations for cars, etc.) be a potential source of infection.
In recent years, species of Legionella linked to other environments have been discovered, such as Letionella antarctica, isolated in sediments of a freshwater lake in Antarctica, which is the genetically closest variant to that of Mallorca.
Bennàsar highlighted the importance of continuing to expand knowledge about legionella, “an opportunistic pathogen of health concern”.
Crespí, S. et al. “Legionella Maioricensis, a new species isolated from the hot water distribution systems of a hospital and a shopping center during routine sampling”. International Journal of Systematic and Evolutionary Microbiology (2023)