Legionella pneumophila monoclonal antibody subgroups and DNA sequence types isolated in Canada between 1981 and 2009: Laboratory Component of National Surveillance

Abstract

Legionella pneumophila (Lp) is a significant cause of nosocomial, community-acquired, and travel-associated pneumonia in industrialized regions. Legionellosis has been a nationally notifiable disease in Canada since 1986, with an average of 75 cases reported annually; however, only the most severe, and often fatal, cases are reported or investigated. Here, epidemiological relationships, types, and distribution of Lp referrals to the Canadian national reference center were studied. Lp strains from different years, sources, and geographic locations were subtyped using a sequence-based typing (SBT) scheme and by the 'Joly' and/or 'Dresden' monoclonal antibody panels. Included were 128 epidemiologically unrelated clinical and 86 unrelated environmental strains. Sixty-four (index of diversity [IOD] = 0.964) and 45 (IOD = 0.888) sequence types (STs) were observed among clinical and environmental sources, respectively. Serogroup (sg) 1 was represented by 60.2% (77/128) and 52.3% (45/86) of clinical and environmental strains, respectively, and 63.6% (49/77) and 15.6% (7/45) of those were mAb2-positive, respectively. Serogroup 1, ST1 accounted for 14.1% (18/128) and 30.2% (26/86) of unrelated clinical and environmental isolates, respectively. This database will serve as a basis for Canadian epidemiological surveillance efforts and is linked to global surveillance initiatives curated by the European Working Group for Legionella Infections (EWGLI) network.

Prevalence of 7 virulence genes of <i>Legionella</i> strains isolated from environmental water sources of public facilities and sequence types diversity of <i>L. pneumopila</i> strains in Macau

“…One report in South Korea showed that the mompS locus had the most alleles (2). Similarly, another study conducted in Canada obtained the same result that locus mompS provided the most alleles (22). However, one study on SBT of L. pneumophila strains in mainland China indicated that mip and flaA individually provided the most alleles in the isolates from cooling water and hot spring water (19).…”

“…Among eight complexes generated in the minimum spanning tree, only four were related to Macau STs. The subtype distribution of L. pneumophlia strains isolated from Macau was not as extensive as that from other cities (20,22,23). However, in complex I, ST1 from Macau was the major STs involved in, which reflects the concentration of local types.…”

Insertion Sequences as Highly Resolutive Genomic Markers for Sequence Type 1 Legionella pneumophila Paris

“…A consensus trend emerged, with all data revealing both a high level of genetic diversity in Legionella and the emergence of specific groups of clones that showed high similarities and were responsible for both sporadic legionellosis cases and worldwide outbreaks (1,4,26,34,35,37,49,58). In particular, isolates from ST1 (which includes the widely distributed Paris strain), ST47, and ST222 have been detected in sporadic and outbreak cases.…”

“…Several studies combined these different methodologies to infer the distribution of Legionella isolates, especially from L. pneumophila serogroup 1, using collections of isolates sampled all over the world-in Japan (1), Canada (49,58), the United States (35), South Korea (37), and Europe (22,23,26). A consensus trend emerged, with all data revealing both a high level of genetic diversity in Legionella and the emergence of specific groups of clones that showed high similarities and were responsible for both sporadic legionellosis cases and worldwide outbreaks (1,4,26,34,35,37,49,58).…”

The N -Acylneuraminate Cytidyltransferase Gene, neuA , Is Heterogenous in Legionella pneumophila Strains but Can Be Used as a Marker for Epidemiological Typing in the Consensus Sequence-Based Typing Scheme

“…By using the published neuA primers (15), standard SBT could be applied in all strains belonging to SG1 and to some other SGs. However, in some non-SG1 L. pneumophila strains, the neuA gene could not be amplified (1,11,16,20). It was considered likely therefore that this was due to either the heterogeneity of neuA DNA sequence preventing primer binding or the absence of the gene in some of these non-SG1 strains, as suggested by microarray analysis (3).…”