Rapid Diagnosis of Intravascular Catheter-Associated Infection by Direct Gram Staining of Catheter Segments

Abstract We conducted a study to determine the usefulness of the Gram stain in the detection of intravascular catheter-associated infection. A total of 330 intravascular catheters were prospectively collected from adults and children suspected of having such an infection. Semiquantitative solid-agar cultures of the distal catheter tip were correlated with blood cultures. Catheter-associated bacteremia occurred in 34 per cent of cases in which catheter tips were colonized (≥15 colonies per agar plate). There were no cases of catheter-associated bacteremia in patients with uncolonized catheters. Immediately after culture, whole catheter segments were stained by the Gram technique. Gram-negative and gram-positive bacteria and yeast were easily identifiable under oil immersion (X1000), located predominantly on external catheter surfaces. Any catheter with at least one organism per 20 oil-immersion fields was designated as positive by Gram stain, but the majority of the 41 positive catheters had much larger nu...