Legionella are Gram-negative aerobic bacilli that live in fresh and man-made water environments.
Legionella bononiensis, magnification 20 ,000x. Image credit: Girolamini et al., doi: 10.1099/ijsem.0.005512.
Legionella, the only genus of the family Legionellaceae, acquired its name after an outbreak in 1976 of a then-unknown ‘mystery disease’ sickened over 200 people. The outbreak was first noticed among attendees at a convention of the American Legion, an association of U.S. military veterans.
To date, a total of 63 species of Legionella have been characterized, 24 of these are associated with human infections and involved in Legionnaire’s disease and Pontiac fever.
The infection is acquired via inhalation of contaminated aerosol or, less commonly, by aspiration of drinking water.
The new species of Legionella, named Legionella bononiensis, was isolated hot and cold water samples collected from a hotel in Emilia-Romagna region, Italy.
“During planned surveillance activities in a hotel facility, the laboratory staff isolated atypical colonies, which had peculiar morphological and phenotypical characteristics,” said Dr. Sandra Cristino, a researcher at the University of Bologna.
“We analyzed the collected samples using all the standardized methods suggested by reference standards, as well as the scientific literature.”
“However, the results obtained were discordant and did not allow the identification of bacteria at a species level.”
To obtain more precise answers, Dr. Cristino and her colleagues turned to genetic sequencing, the reference test for identifying microorganisms isolated environmentally or clinically.
They then further delved into the sequencing activity by analyzing other Legionella-specific genes.
They also conducted phenotyping, whole genome sequencing and mass spectroscopy studies.
“The obtained results confirmed what we had observed in culture: we were dealing with a new species, phylogenetically distant from Legionella quateirensis, which has never been documented in scientific literature,” Dr. Cristino said.
“We then began the process of officially recognizing the strain by depositing samples at two culture collections in two different countries, as required by the leading journal that allows the description of new species of prokaryotes.”
“It is essential to continue studying the pathogenicity and infectivity of the newly discovered strain, as well as the pattern of antibiotic resistance, in order to be able to carry out public health prevention activities.”
“In addition, the lab is working on two new isolates, which turn out to be two new species of the genus Legionella.”
The team’s findings were published in the International Journal of Systematic and Evolutionary Microbiology.
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Luna Girolamini et al. 2022. Legionella bononiensis sp. nov., isolated from a hotel water distribution system in northern Italy. International Journal of Systematic and Evolutionary Microbiology 72 (9); doi: 10.1099/ijsem.0.005512
