The sterile containers containing the PNC were stored at 4°C and were sent to the laboratory the same day for microbiological analysis of the PNC: The PNC were rolled onto sheep blood agar plates (Becton Dickinson BD, Basel, Switzerland) similar to the semiquantitative culture method for intravenous catheters [10] and thereafter immediately transferred to a liquid enrichment medium (thioglycolate medium, BD Basel Switzerland). Sheep blood agar was incubated for 2 days and thioglycolate for 5 days. In case of growth in the enrichment media only, an aliquot of the liquid was subcultured on solid media. Reports were considered to be positive if any growth was present. Identification of the isolated bacteria and susceptibility testing were performed according to standard methods.