Organisms in the genus Enterococcus are facultative anaerobic Gram positive cocci. In neonates, enterococcus may cause meningitis and bacteremia, and endocarditis in adults. Enterococcus are one of the leading causes of problematic nosocomial infections, particularly in intensive care units. The major problem with these organisms is that they can be very resistant to antibiotics (e.g. vancomycin).