**Abstract**

Enterococci, the Gram-positive, catalase negative, non-spore forming and aerotolerant fermentative organisms form the second largest group of bacteria studied with reference to microbial source tracking in view of their ability to survive adverse environmental conditions and adaptable nature to revolutionize from low number commensals to a predominant population of host microbiota thus creating a consequence for pathogenesis. Despite being a member of normal human intestinal flora, they are not regarded anymore as generally recognized as safe (GRAS) organisms and some of its species may turned out to be a major cause of nosocomial infections. Ecological and epidemiological studies showed that these bacteria enter in the environment via feces and colonize because of their high adaptability. The main contributors in pathogenesis of enterococci are the presence of various virulence factors and antibiotic resistance genes. This chapter aims to highlight the infections caused by enterococci and their respective virulent determinants.

**Keywords:** *enterococcus*, virulence, resistance, hemolysis, lactic acid bacteria, nosocomial infections
