Enterococci

They are part of the normal intestinal flora of humans. They have gained notoriety due to antibiotic resistance to various drugs. The medically important species are E.faecalis and E.faecium. As they react with Group D antisera they were originally classified as Group D streptococci. They are now known to be very distinct from them.

Morphology

They appear as gram positive cocci in pairs, tetrads and small chains. They are alpha or non hemolytic on blood agar.

Classification

Not important for exam :)

Human pathology

They cause UTIs especially following genitourinary instrumentation, endocarditis, bacteremia, wound infections and catheter related infections etc.

Laboratory diagnosis of enterococcal infections

Gram stain and culture will show typical findings. They have a characteristic feature of being able to grow in 6.5% NaCl. They can hydrolyze esculin in the presence of bile, are not killed by Penicillin G, hydrolyze pyrrolidonyl-beta-naphthylamide (PYR), produce leucine aminopeptidase and can grow at both 10 degree C and 45 degree C.