Comparison of the Roll Plate Method to the Sonication Method To Diagnose Catheter Colonization and Bacteremia in Patients with Long-Term Tunnelled Catheters: a Randomized Prospective Study

Abstract

Diagnosing catheter-related bloodstream infection (CRBSI) still often involves tip culture. The conventional method is the semiquantitative roll plate method. However, the use of a quantitative sonication technique could have additional value, as it may detect endoluminal microorganisms more easily. Because endoluminal infection tends to occur in long-term central venous catheters, we compared both techniques for patients with long-term tunnelled catheters. For 313 consecutive Hickman catheter tips from 279 hematological patients, colonization detection rates were compared by performing both techniques in a random order, using conventional detection cutoffs. Additionally, for the subgroup of patients with clinical suspicion of CRBSI (n ‫؍‬ 89), the diagnostic values of both techniques were compared. The overall tip colonization rate was 25%. For each technique, the detection rate tended to be better if that technique was performed first. The diagnostic performance for the subgroup of patients with clinical suspicion of CRBSI was limited and not different for both methods. Sensitivity and specificity were 45% and 84%, respectively, for sonication versus 35% and 90%, respectively, for the roll plate technique. The fact that 35 of 40 patients with CRBSI received antimicrobial therapy before catheter removal and tip culture, in an attempt to salvage the catheter, may partly explain this poor performance. No differences were observed when catheters were stratified according to in situ time below or above the median of 4 weeks. The sonication culture technique was not better than the roll plate method to diagnose tip colonization or CRBSI in patients with long-term tunnelled catheters.

Sonication of catheter tips for improved detection of microorganisms on external ventricular drains and ventriculo-peritoneal shunts

“…The efficacy of sonication as opposed to alternative detachment methods has been shown in one experimental model [23], but other investigators found no advantage over conventional methods [24,25]. Although we have not compared this new method to other methods of culturing catheters such as the Maki roll-out method [26] it appears that sonication culture of catheter tips may improve the diagnosis of catheter-related meningoventriculitis.…”

Bacteriological profile and their antimicrobial susceptibility pattern in central venous catheter tip culture

“…Using sterile forceps, the catheter tip was removed from transport tube and laid on Blood agar plate. The tip was rolled back and forth across the entire surface of blood ager plate using sterile forceps and exerting slight downward pressure and incubated aerobically at 37 0 C. 4,5 Agar plates were examined at 24 hours, 48 hours and 72 hours. Significant growth was defined as >=15 colony forming unit.…”

Density of Microbial Colonization on External and Internal Surfaces of Concurrently Placed Intravascular Devices

“…Microbial colonization was heaviest on the external surfaces of IVDs, suggesting that the devices are colonized down from the proximal end of the catheter toward the distal tip, possibly originating from the skin around the IVD insertion site. Our finding that microbial growth was heaviest on the surfaces of the proximal intravascular segment of the IVDs brings into question the current reliance on culturing only the tip of a catheter to diagnose CRBSI, [21][22][23] a choice based on the apparent assumption that regardless of microbial colonization of different parts of a catheter, the risk for blood-borne microbial dissemination does not begin to increase markedly until colonization at the tip reaches a level of more than 15 CFUs/mL. The number of CRBSIs in our study was insufficient to confirm this assumption.…”