Genetic analysis of human clinical isolates of Lactococcus garvieae: Relatedness with isolates from foods

摘要

Lactococcus garvieae is a Gram-positive bacterium well-known as an important pathogen in aquaculture, and it is also a human pathogen of increasing clinical significance. Forty-three human L. garvieae isolates from clinical specimens were characterized by Multilocus Sequence Typing (MLST). Twenty-six different sequence types (STs) were identified among the human isolates, of which 20 were novel STs. Most human isolates clustered into four clonal complexes, with a predominance of CC3. Within CC3, ST10 was the most common genotype, indicating the existence of a circulating genetic lineage among the human isolates analyzed. The four CCs also grouped L garvieae strains isolated from meat, dairy and fish, indicating a genetic overlap between isolates from human and these foods. Genetic relatedness among human and food L garvieae isolates was confirmed by phylogenetic analysis based on the concatenated sequences of the seven MLST genes. These results represent the first evidence of genetic relatedness between isolates of L garvieae of human and those isolated meat, milk and dairy products and suggest that, in addition to fish and seafood, these foods might represent important sources of human L garvieae infections. (C) 2015 Elsevier B.V. All rights reserved.