Robust MLPA find more clusters of strains with identical STs or belonging to CCs were identified among the population, mainly among the 3 main clades this study. Each of these clusters included a limited number of strains (2 to 6 strains) that were further shown to be unrelated based on epidemiological data and/or PFGE results, and 52 out of the 191 fully analyzed strains (27.2%) were involved in these clusters. Twelve clusters grouped
strains from a unique host, i.e., a fish-associated subset within A. salmonicida and 11 human-associated subsets within the A. veronii (n = 6), A. caviae (n = 3) and A. hydrophila (n = 2) clades. Nine of these subsets included only disease-associated strains. Notably, all of the A. veronii human-associated clusters were disease associated. Among these clusters, ST13, which was shared by 6 strains of human origin and was mainly recovered during wound infections, may reflect a host (niche)-adapted pathogenic cluster among the A. veronii clade, which was otherwise characterized by high genetic diversity. The striking, unique PFGE pattern and ST may reflect the adaptation of this cluster to a niche in which genetic and genomic variability is not permitted due to strong constraints. However, because of the small number of strains included in these clusters, an increased number of strains should be studied to confirm whether specific lineages or CCs are more likely to contain
clinical isolates or be associated with a specific illness. The present see more study showed a relatively low frequency of recombination events compared to previous studies [15, 28]. This result may originate in the Selleck MGCD0103 differences between these studies in the genes evaluated and the population sampling strategies employed. The population sample studied by Martino et al. differed significantly from ours, as most of their isolates were obtained from fish, crustaceans
or mollusks . Silver et al. deliberately included a very small number of isolates (n = 12) of host-associated strains (e.g., only strains isolated from leeches, human wounds or human feces), which may constitute a recruitment bias because these strains may be host Dimethyl sulfoxide adapted . Interestingly, the recombination events encountered in our study were predominantly observed within clonal complexes (e.g., CC “D”, grouping A. veronii strains recovered during human diarrhea episodes), which supported the previous hypothesis of the study by Silver et al. . Taxonomic considerations MLPA may be helpful for identification purposes. Indeed, strains that have previously rarely been reported in the literature were recognized among the study population, among which an A. jandaei isolate from a human urinary tract infection and an A. allosaccharophila strain recovered during human bacteremia were particularly remarkable. Moreover, MLPA may allow the correct identification of strains deposited in strain collections under erroneous or incomplete nomenclature, as observed for A.