The West Bank can be considered a high-risk area for Legionnaires’ disease (LD) due to
its hot climate, intermittent water supply and roof storage of drinking water. Legionella, mostly
L. pneumophila, are responsible for LD, a severe, community-acquired and nosocomial pneumonia.
To date, no extensive assessment of Legionella spp and L. pneumophila using cultivation in combination
with molecular approaches in the West Bank has been published. Two years of environmental
surveillance of Legionella in water and biofilms in the drinking water distribution systems (DWDS)
of eight hospitals was carried out; 180 L. pneumophila strains were isolated, mostly from biofilms in
DWDS. Most of the isolates were identified as serogroup (Sg) 1 (60%) and 6 (30%), while a minor
fraction comprised Sg 8 and 10. Multilocus Variable number of tandem repeats Analysis using
13 loci (MLVA-8(12)) was applied as a high-resolution genotyping method and compared to the
standard Sequence Based Typing (SBT). The isolates were genotyped in 27 MLVA-8(12) genotypes
(Gt), comprising four MLVA clonal complexes (VACC 1; 2; 5; 11). The major fraction of isolates
constituted Sequence Type (ST)1 and ST461. Most of the MLVA-genotypes were highly diverse and
often unique. The MLVA-genotype composition showed substantial regional variability. In general,
the applied MLVA-method made it possible to reproducibly genotype the isolates, and was consistent
with SBT but showed a higher resolution. The advantage of the higher resolution was most evident
for the subdivision of the large strain sets of ST1 and ST461; these STs were shown to be highly
pneumonia-relevant in a former study. This shows that the resolution by MLVA is advantageous for
back-tracking risk sites and for the avoidance of outbreaks of L. pneumophila. Overall, our results
provide important insights into the detailed population structure of L. pneumophila, allowing for better
risk assessment for DWDS.