Should We Use Intravenous Catheter Tip Cultures in the Determination of Bloodstream Infections?

BACKGROUND/OBJECTIVES: Intravenous catheter (IVC) tips are often cultured when IVC lines are removed from febrile patients to help determine if the patient has a line-related bloodstream infection (BSI). We wanted to determine the reliability and cost-effectiveness of IVC tip cultures in predicting bacteremia and BSI in our institution. METHODS: We perform surveillance for and maintain a database of all bloodstream infections in our 400 bed facility. Centers for Disease Control and Prevention (CDC) definitions are used. We reviewed all (339) IVC tip cultures obtained from January 1-June 30, 2005. Positive tip cultures were defined as greater then 15 colony-forming units (cfu) via the semi-quantitative roll plate method. Positive tip cultures were compared with our BSI database to determine if the culture was associated with a bloodstream infection. IVC tip cultures without a blood culture done within 24 hours of the tip culture were excluded from analysis (119 (35%)). Positive tip cultures with an associated positive blood culture were examined to determine if CDC BSI criteria were met and the patient was in our database. Cost information was obtained from the laboratory. RESULTS: Of 339 IVC tips cultured, 59 (17%) were deemed positive. 222 (65%) of tip cultures were associated with a blood culture done within 24 hours either before or after the tip culture. 246 (73%) cultures were negative for both IVC tip and blood. 13 cultures were positive for both the IVC tip and blood. Of these, 1 had a positive blood culture after the positive tip culture within 24 hours but with a different organism. Twelve had positive blood cultures before the tip culture. The predictive value of a positive tip culture (PVP) was 0/15 = 0%. The predictive value of a negative culture was 246/280 = 88%. The cost to the laboratory of processing a negative tip culture is $71, while the cost of processing a positive culture is $124. The annualized cost of IVC tip cultures in the adult critical care units is $33,142. The estimated cost hospital-wide is $54,392. CONCLUSIONS: Our data do not support the use of IVC tip cultures for the prediction of bacteremia or BSI. Discontinuation of the practice could save the hospital thousands of dollars per year. On the basis of these findings, our institution has stopped performing routine culture of IVC tips. This change has been accepted without objections.