New aspects of staphylococcal infections: emergence of coagulase-negative staphylococci as pathogens.

In contrast to the well-established pathogen Staphylococcus aureus, the coagulase-negative staphylococci, formerly collectively called S. epidermidis, were until recently regarded as harmless commensals. During the last two decades, however, the coagulase-negative staphylococci have clearly emerged as pathogens in patients carrying artificial devices, such as prosthetic heart valves, hip prostheses and cerebrospinal fluid shunts, and in patients with compromised host defenses such as premature neonates and cancer and transplant patients. The present paper reviews current insights on classification, bacteriology, pathogenic potential and virulence factors of coagulase-negative staphylococci. In addition, the role of host defense factors in resistance to staphylococcal infection is summarized as well as the main features of the clinical syndromes in which coagulase-negative staphylococci are involved.