Bloodstream infection after positive catheter cultures: what are the risks in the intensive care unit when catheters are routinely cultured on removal?

OBJECTIVES

The aim of the study was to assess whether an isolated positive catheter culture is predictive of a subsequent bloodstream infection in intensive care unit patients.

DESIGN

Retrospective clinical study between 2000 and 2007.

SETTING

Intensive care unit of a university hospital.

SUBJECTS

All arterial, central venous, and dialysis catheters yielding selected pathogenic microorganisms from isolated positive catheter cultures. Positive catheter culture was defined by a catheter tip culture performed with the Brun-Buisson technique yielding ≥103 colony-forming units/mL; isolated positive catheter culture by a positive catheter culture without concomitant bloodstream infection due to the microorganism of the positive catheter culture evidenced within 48 hrs before or after catheter removal; and subsequent bloodstream infection by a bloodstream infection developing between 48 hrs and 30 days after catheter removal and due to a selected pathogenic microorganism of an isolated positive catheter culture. Active antibiotic therapy was active if at least one of the antibiotics administered was effective against the selected pathogenic microorganism of the positive catheter culture.

INTERVENTION

None.

MEASUREMENT AND MAIN RESULTS

The end point of the study was the ratio of the number of subsequent bloodstream infections to that of selected pathogenic microorganisms isolated from positive catheter culture 30 days after catheter removal. A total of 138 isolated positive catheter cultures for 149 selected pathogenic micro-organisms was included in the study. Only two cases (1.3%) of subsequent bloodstream infection were evidenced, one resulting from Escherichia coli and the other from Staphylococcus epidermidis. The incidence of subsequent bloodstream infection did not differ with regard to the presence or absence of active antibiotics at catheter removal: zero of 23 vs. two of 121 (p = 1), respectively.

CONCLUSIONS

Our results suggest that the risk of subsequent bloodstream infection in intensive care unit patients when the Brun-Buisson technique is used to define isolated positive catheter culture is low.