The benefits of Isolator cultures in the management of suspected catheter sepsis.

Until recently, when a patient receiving total parenteral nutrition (TPN) was suspected of having catheter-related sepsis, the catheter was removed and the tip and the patient's blood was cultured. Using this method at our institution, greater than two thirds of the central venous catheters (CVC) removed were sterile, or if colonized, proved not to be the source of sepsis. This practice led to the unwarranted removal of numerous catheters and posed a clinical dilemma because it necessitated replacement of the catheter with its attendant risks, cost, and inconvenience. To address this problem, we instituted a protocol for determining in situ catheter-related sepsis based on a quantitative blood culture method using lysis centrifugation (Isolator; Dupont Co., Wilmington, Del.). When catheter-related sepsis was clinically suspected, quantitative blood cultures were obtained simultaneously via a peripheral (PER) vein and through the CVC suspected as the source of sepsis. The CVC, however, remained in situ pending culture results (approximately 16 to 24 hours). A CVC colony of greater than or equal to five times the PER colony count was considered significant and the catheter was removed. Equivocal colony counts between the CVC and PER cultures were interpreted as incriminating a source of sepsis other than the CVC. An 8-month prospective study was undertaken to evaluate the efficacy of this method for determining in situ catheter sepsis. One hundred third-eight patients received TPN by means of 160 catheters. In 113 patients no sepsis-related problems were noted. In the remaining 25 patients, 28 catheters were suspected as the source of sepsis. Twenty-six catheters were evaluated by the Isolator culture method. In eight instances significant differences in colony counts between the CVC and PER cultures were seen, implicating the CVC as the source of infection. In all these cases the CVC was removed and the patients underwent defervescence. In 18 cases, the CVC samples revealed either no growth or insignificant differences between the CVC and PER colony counts. Nine of these CVCs were removed without clinical improvement. The remaining nine catheters were left in place, and another source of sepsis was ultimately identified and treated. These results confirm the use of the quantitative blood culture method for determining in situ catheter-related sepsis. In all cases, when the catheter was incriminated by culture data, removal of the CVC led to patient improvement.(ABSTRACT TRUNCATED AT 400 WORDS)