Statistically discernible distribution of Selleckchem Ro-3306 virulence-markers along the up-to-down-gradient landscape was observed (Table 3). In addition, the active gelatinase phenotype was observed in 19.05% E. faecalis isolates [see Additional file 2]. The background level of virulence-markers in the up-to-down gradient landscape exist at least for two virulence-markers predominantly gelE + esp + (26.19%) followed by gelE + efaA + (7.14%). The only exception was site 3 with median value of one which otherwise exhibited the range of Tucidinostat manufacturer one to four virulence-markers gelE + efaA +, gelE + efaA + esp +,gelE + ace + efaA + and gelE + ace + efaA + esp
+. The impact of landscape and associated environmental factors seem to affect the dissemination of all four virulence-markers at site 3 which receives contamination from hospital wastes, municipal sewage and tannery
effluents. Enterococci isolates from the most polluted downstream site exhibited a range of two to three virulence-markers per isolate; gelE + esp + and gelE + efaA + esp + combinations were the most prevalent multiple-virulence-traits. Significantly, the correlation of four virulence-markers was identified either singly or in combination with Enterococcus spp. diversity from river Ganga surface waters (Table 4). Earlier reports on dissemination of virulence-markers in PND-1186 mw different enterococci suggest virulence-markers are common trait in the genus Enterococcus[7, 32–34]. A recent study has reported the prevalence of gelatinase phenotype of enterococci mafosfamide in agricultural environment and suggested it as reservoir of clinically relevant strains [35]. The pervasiveness of virulence-markers investigated in the current study may be due to the evolution of pathogenic enterococci by natural conjugation in environmental waters that receive potential pathogenic enterococci from various point and non-point sources including urban land use, agriculture, intensive livestock operations, hospital and industrial wastes. The natural processes are too complex to comprehend although the transconjugation experiments
conducted elsewhere demonstrated in vitro transfer of additional virulence determinants from clinical strains to starter strains [7]. In the present study, the phenotypic assay for gelatinase activity revealed that certain E. faecalis and different Enterococcus spp. isolates contained apparently silent gelE determinant. This observation is supported by an earlier report on presence of silent gelE gene possibly due to inactive gene product or down regulation of gene expression influenced by various environmental factors resulting in lack of phenotypic activity [7]. Further, the activation of silent genes by temporal factors existing in our body, the response of other commensal microbes in the gastrointestinal tract and the persistent presence of large numbers of preexisting commensal enterococci cannot be ignored.