Multimethod typing reveals predominance of ST1 and detection of a novel sequence type among Legionella pneumophila from hotels plumbing systems in Morocco

ABSTRACT

Legionnaires' disease is an infection caused by Legionella, a waterborne pathogen found in aquatic environments, particularly hot water plumbing systems and cooling towers. A selection of 29 Legionella pneumophila strains isolated from hotels hot water systems were typed by monoclonal antibodies, pulsed-field gel electrophoresis (PFGE) and new generation sequencing (NGS). MAb analysis results demonstrated a prevalence of MAb 3/1 negative isolates (n = 100%), with six subgroups of Camperdown (30%), seven Oxford (35%) and seven OLDA (35%). PFGE analysis showed three different clones, some of which are present in several buildings in different Moroccan cities. After sequencing, SBT (sequence-based type) analysis showed 3 sequence types (STs) with a high prevalence of ST1 found in 13 strains (65%), followed by ST560 in 4 (20%), and a new ST was found in 3 samples (15%), to which ESGLI assigned the ST number ST2897. 46% of ST1 are Oxford, 23% of Camperdown and 31% of OLDA. These findings revealed the genetic diversity of environmental L. pneumophila strains in Morocco, enriching the database and providing a useful basis for epidemiological investigations related to travel-associated diseases.