Use of ribotyping to investigate tracheal colonisation by Staphylococcus epidermidis as a source of bacteremia in ventilated newborns.

Ribotyping was used to determine whether a relationship exists between endotracheal tube colonisation with Staphylococcus epidermidis and bacteremia with this organism. Over a three-week period, four mechanically ventilated preterm babies presented with five episodes of infection and bacteremia. For each blood specimen obtained for culture a tracheal aspirate sample was collected at the same time by suctioning. After DNA extraction and cleavage by EcoRI, hybridisation was performed with a digoxigenin-labelled 16S-rDNA probe from Escherichia coli. Five different band patterns were recognised on the membrane. In two children the same band pattern was found in Staphylococcus epidermidis isolated from both blood and tracheal aspirate. Ribotyping thus could be used to differentiate a series of infections from an outbreak and showed that a relationship may exist between tracheal colonisation and bacteremia in mechanically ventilated newborns.