Comparison of contamination rates of catheter-drawn and peripheral blood cultures
Introduction
Contamination of blood culture specimens is a common and costly problem.1 Some studies have demonstrated that bacterial contamination is higher for catheter-collected specimens,2, 3, 4 while others suggest that there is no significant difference.5, 6, 7, 8 Further studies are required to resolve this. This study compared the sensitivity, specificity and positive and negative predictive values of peripheral and catheter-drawn cultures.
Section snippets
Methods
Paired peripheral and catheter-drawn blood cultures were assessed as being true or false positives using retrospective chart review and microbiology data. Analysis was made of the contamination rate, true bacteraemia rate, sensitivity, specificity and positive and negative predictive values.
The ‘Kestral’ pathology database of the Mater Hospital, Brisbane was searched for all blood cultures for which the site of collection was specified between January 1998 and August 2002. In total, 8444 blood
Results
Of the 962 pairs of blood cultures that were included in the study, the culture results were concordant in 797 pairs. In 659 pairs, both cultures were negative, and in 138 pairs, both cultures were positive for the same organism. Of the 165 discordant pairs, 132 had negative peripheral venous cultures and positive catheter cultures. Seven of these were determined as true bacteraemias while 125 were determined to be contaminants. The remaining 33 discordant pairs tested positive from the
Discussion
False-positive blood cultures are a major problem for clinicians and pathologists. The optimal strategy to minimize false positives remains controversial, as the results of studies have been conflicting. In this study, a large retrospective analysis of blood cultures was performed. The study found that catheter-drawn blood cultures have a low specificity and positive predictive value compared with peripheral cultures. The sensitivities were similar for the two groups.
These findings are in
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Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line-associated bloodstream infections
2015, American Journal of Infection ControlCitation Excerpt :Snyder et al in 2012 conducted a systematic review of studies comparing bacterial colonization of BCs drawn either through venipuncture routes or from intravascular catheters.52 The 9 studies53-60 reported higher BCC rates ranging for samples drawn via catheters (range, 3.4%-13%) than from blood obtained by venipuncture (range, 1.2%-7.3%). Higher contamination rates occur at the time of central line insertion despite a maximal sterile technique.61
Development of subsequent bloodstream infection in patients with positive Hickman catheter blood cultures and negative peripheral blood cultures
2011, Diagnostic Microbiology and Infectious DiseaseCitation Excerpt :Physicians occasionally encounter patients who have positive catheter-drawn blood cultures (CBC) and negative peripheral blood cultures. Previous studies have indicated that these discordant results occur in 6–14% of paired blood samples, but there are limited data on the clinical significance and management of these situations (Beutz et al., 2003; DesJardin et al., 1999; Martinez et al., 2002; McBryde et al., 2005). The main findings of present study are that isolated positive catheter blood cultures are associated with an 8% incidence of subsequent BSI in cancer patients with indwelling HCs, and that these complications were more common in patients who did not receive appropriate empiric antibiotics.
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