Characterization of coagulase-negative staphylococci causing nosocomial infections in preterm infants.

The species spectrum, antibiotic susceptibility, and genomic profile of coagulase-negative staphylococci (CNS) isolated from infected preterm infants were compared with those obtained in CNS from nursery personnel. Staphylococcus epidermidis was the predominant species in the 66 investigated preterm infants (171 isolates), accounting for 64% of all isolates. A high proportion of Staphylococcus haemolyticus (32%) could be detected. In contrast to the results in patients, the spectrum in nursery personnel was broad and included more species of CNS. All isolates of CNS from preterm infants demonstrated a low rate of susceptibility to the beta-lactam antibiotics (2% sensitivity to penicillin and 6% sensitivity to oxacillin). Sensitivity to gentamicin (9%) was also rare. An unexpected observation was susceptibility to teicoplanin in only 70% of all CNS isolated from patients due to the high proportion of Staphylococcus haemolyticus. Analysis of the genomic profile of 33 isolates of Staphylococcus haemolyticus by pulsed-field gel electrophoresis revealed a relationship between the strains. An outbreak of one particular strain of Staphylococcus haemolyticus in the neonatal intensive care unit investigated can therefore not be excluded.