# Dissemination of Enterococcuscal Genetic Lineages: A One Health Perspective
## 4 Enterococcal Genetic Traits: Dissemination in the One Health Continuum
### Human Healthcare-Associated Genetic Traits  
As aforementioned, enterococci have emerged as one of the most frequent causes of infections in clinical and healthcare settings [56]. Among all species of _Enterococcus_ spp., _E. faecalis_ and _E.ecium_ are the main healthcare-related pathogens, despite a fast-epidemic growth of multidrug-resistant _E. facoium_ clones, which has resulted in increased prevalence of _E. facoium_ in comparison to _E. faecalis_[15; 57]. According to previous studies [29; 58] using MLST, there are host-specific genetic clusters of _E. faecalis_ and _E. facoium_ isolated from hospital-acquired infections, defined as clonal complexes (CCs), in which a variety of sequence types (STs) are assembled. From an evolutionary perspective, the gain and loss of virulence and ARGs via MGEs directly influence the emergence of new specific lineages in a particular geographic area, which could quickly disperse in healthcare-associated settings worldwide [59; 60]. The existence of certain resistance genes and virulence factors in a specific local environment induces the acquisition of these traits by epidemic clones via HGT, which may influence evolutionary development toward genetic subpopulations, completely adapted to healthcare settings [58]. Table 2 summarizes some genetic features of the most relevant enterococcal clinical clonal lineages. Given the worldwide heterogenous epidemiology, data are displayed focusing on STs. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Species**} & \multirow{2}{*}{**Source**} & \multirow{2}{*}{**Location (Date)**} & \multirow{2}{*}{**Clade**} & \multicolumn{3}{c}{**Clonal lineages**} & \multirow{2}{*}{**Virulence**} & \multirow{2}{*}{**Antimicrobial**} & \multirow{2}{*}{**Resistance Genes**} & \multirow{2}{*}{**Ref.**} \\ \cline{5-8} \cline{7-9}  & & & & & **MST Sequence Type** & & & & \\ \hline \multirow{5}{*}{_E. faecalis_} & \multirow{5}{*}{\begin{tabular}{c} Septicemias and \\ endocarditis \\ \end{tabular} } & \multirow{5}{*}{Worldwide} & \multirow{5}{*}{NA} & \multirow{5}{*}{ST2} & \multirow{5}{*}{CC2} & \multirow{5}{*}{_gdE_} & \multirow{5}{*}{_h2Z_, _anc_/_gd_-_sph_2_.\"} & \multirow{5}{*}{[61; 62; 63]} \\ \cline{5-8} \cline{8-9}  & & & & & & _csp_, _gdE_ & _whz_, _anc_/_gd_-_sph_2_.\", _emh_, _snuA_, _cunB_ & & [61; 63] \\ \cline{1-1} \cline{2-9}  & \multirow{2}{*}{\
\begin{tabular}{c} Healthcare- \\ insecticides \\ \end{tabular} } & \multirow{2}{*}{Worldwide (first in Argentina the USA)} & \multirow{2}{*}{NA} & \multirow{2}{*}{ST9} & \multirow{2}{*}{CC9} & \multirow{2}{*}{_exp_, _gdE_} & \multirow{2}{*}{_whz_, _anc_/_gd_-_sph_2_.\"} & \multirow{2}{*}{[29; 61; 64]} \\ \cline{5-8} \cline{8-9}  & & & & & & _csp_, _gdE_ & _whz_, _anc_/_gd_-_sph_2_.\", _emh_ & & [61; 62; 64] \\ \cline{1-1} \cline{2-9}  & \multirow{2}{*}{
\begin{tabular}{c} Beatremia \\ \end{tabular} } & \multirow{2}{*}{Poland} & \multirow{2}{*}{NA} & \multirow{2}{*}{ST28} & \multirow{2}{*}{CC87} & \multirow{2}{*}{_asl_, _anc_/_gd_-_sph_2_.\", _snuA_} & \multirow{2}{*}{[61; 62; 64]} \\ \cline{1-1} \cline{2-9}  & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Most relevant healthcare-associated enterococcal STs. Information was gathered considering enterococcal species allocation, source, geographic location, virulence, and antimicrobial resistance genes. Most _E. faecalis_ isolated from healthcare environments have been associated with HiRECCs such as CC2 and CC9, which have spread globally [29; 64; 72]. However, in Europe, CC87 may replace CC9 as a potential high-risk complex [63]. Particularly, CC2, CC8, and CC9 lineages have revealed higher acquired antimicrobial resistance; CC2, CC16, and CC87 were associated with multidrug resistance, of which CC2 and CC87 were associated with healthcare-associated infections (HAIs) [73]. _E. faecalis_ CC2 comprises various strains in which the genetic determinants are variably present, differences being associated with distinct lineages.