Molecular epidemiology of Staphylococcus epidermidis in a neonatal intensive care unit over a three-year period

Coagulase-negative staphylococci, especially Staphylococcus epidermidis, ar e increasingly important nosocomial pathogens, particularly in critically i ll neonates, A 3-year prospective surveillance of nosocomial infections in a neonatal intensive care unit (NICU) was performed by traditional epidemio logic methods as well as molecular typing of microorganisms, The aims of th e study were (i) to quantify the impart of S. epidermidis on NICU-acquired infections, (ii) to establish if these infections are caused by endemic clo nes or by incidentally occurring bacterial strains of this ubiquitous speci es, (iii) to evaluate the use of different methods for the epidemiologic ty ping of the isolates, and (iv) to characterize the occurrence and the sprea d of staphylococci with decreased glycopeptide susceptibility, Results conf irmed that S. epidermidis is one of the leading causes of NICU-acquired inf ections and that the reduced glycopeptide susceptibility, if investigated h y appropriate detection methods such as population analysis, is more common than is currently realized, Typing of isolates, which can be performed eff ectively through molecular techniques such as pulsed-field gel electrophore sis but not through antibiograms, showed that many of these infections are due to clonal dissemination and, thus, are potentially preventable by stric t adherence to recommended infection control practices and the implementati on of programs aimed toward the reduction of the unnecessary use of antibio tics. These strategies are also likely to have a significant impact on the frequency of the reduced susceptibility of staphylococci to glycopeptides, since this phenomenon appears to be determined either by more resistant clo nes transmitted from patient to patient or, to a lesser extent, by strains that become more resistant as a result of antibiotic pressure.