Coagulase-negative staphylococci are a diverse group of Gram-positive bacteria that lack the enzyme coagulase, differentiating them from the more virulent Staphylococcus aureus. Common species include Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus saprophyticus. They are part of the normal human flora but can become opportunistic pathogens under certain conditions.
