USE OF PULSED-FIELD GEL-ELECTROPHORESIS TO DETERMINE THE SOURCE OF MICROBIAL-CONTAMINATION OF CENTRAL VENOUS CATHETERS

Microorganisms detected in situ on the distal tip of central venous ca theters (CVC) within 90 min of insertion were investigated using pulse d-field gel electrophoresis to analyse genomic fragments obtained with the SmaI restriction enzyme. Thirty patients received a triple lumen CVC, which was inserted directly through the skin using the Seldinger technique, In a further 30 patients a triple lumen CVC was inserted th rough a Swan sheath, thereby avoiding direct contact of the CVC with t he skin. Staphylococci were isolated from the distal tips of the cathe ters in 6 patients (5 who had the CVC inserted directly through the sk in and 1 who had the CVC inserted via a Swan sheath.) Twenty-three sta phylococcal isolates were also isolated from the insertion equipment a nd the skin swabs surrounding the insertion site of these six patients . All the isolates were genotyped. In one of the patients the organism s isolated from the skin were identical to those on the CVC tip. In tw o further patients similar organisms were isolated from the insertion equipment and the patients' skin. These results, in addition to the re duced colonisation rates observed when catheters were introduced throu gh a Swan sheath, support the hypothesis that microorganisms from the skin are impacted onto the CVC tip and the CVC insertion equipment at catheter insertion.