Routine semiquantitative cultures and central venous catheter-related bacteremia.

Semiquantitative cultures were compared with blood cultures during one year in order to see if the routine use of a semiquantitative catheter culture method (SQC) in unselected patients can detect or predict infection associated with central venous catheters. Catheter infection, i.e. greater-than-or-equal-to 15 colony forming units (cfu) per plate, occurred in 137 of 542 catheter tips (25%), mainly with coagulase-negative staphylococci. Catheter-associated bacteremia occurred in 17 of 93 cases (18%) where blood cultures had been drawn. In 15 of these, the catheter tip grew greater-than-or-equal-to 15 cfu. The predictive value for bacteremia of a positive SQC was only 21%. SQC is not a suitable method for the detection of catheter-associated bacteremia, but may be an indicator of the standard of central venous catheter hygiene.