Comparative culture methods on 101 intravenous catheters. Routine, semiquantitative, and blood cultures.

Broth cultures and semiquantitative cultures (SQCs) were done on 101 intravenous (IV) catheters from 82 patients. Catheters were in place an average of ten days (range, one to 40 days). Twenty-eight catheters yielded 15 colonies or more to SQCs of transcutaneous catheter segments. Staphylococcus epidermidis was the most common microbial isolate found on 21 of the 28 catheters on SQC. Broth tip cultures, SQCs on tips and transcutaneous segments, qualitative blood cultures (QIBCs), and quantitative blood cultures (QnBCs) drawn via the catheters were significantly associated with peripheral bacteremia. The presence of systemic antimicrobials made no significant difference in SQC, QIBC, or QnBC positivity. With the exception of gross pus, local inflammation was not significantly associated with catheter infection. Local site care by a special team of nurses resulted in significantly fewer catheter infections than did care given by ward nurses.