Sonicating multi-lumen sliced catheter tips after the roll-plate technique improves the detection of catheter colonization in adults

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Highlights

  • We assessed in 252 CVC tips the yield of Maki and sonication (after slicing) to predict colonization and C-RBSI.

  • Maki and sonication were both positive only in 58.3% and 60.0% of the colonized catheters, respectively.

  • Sonication recovered > 25.0% of the colonized catheters and C-RBSI episodes that would have gone undetected by Maki.

  • We recommend performing both techniques in the Microbiology laboratory to detect catheter tip colonization.

Abstract

The Maki technique is the standard method for detecting catheter tip (CT) colonization. However, some “multi-lumen” catheters finish in a vaulted fornix and end at different distances from the CT. Therefore, we compared the traditional Maki technique with the sonication method using several cross-cut fragments of the CT. Our objective was to assess the yield of the Maki technique followed by sonication in the detection of adult CT colonization and catheter-related bloodstream infection (C-RBSI). For 3 months, we prospectively performed CT cultures of polyurethane catheters from adult patients admitted to our institution. First, we performed CT culture using the Maki technique on blood agar plates and then sonicated small fragments of CTs in 5 ml of BHI followed by culture of 100 μl of the sonicate. We included a total of 252 CVCs, with overall colonization and C-RBSI rates of 14.3% (36/252) and 5.9% (15/252). Of the 36 colonized CVCs, 21 (58.3%) were detected both by Maki and sonication, 6 (16.7%) were detected only by Maki technique, and 9 (25.0%) only by sonication method. Among 15 episodes with concomitant bacteremia, both techniques were positive and concordant in 9 cases (60.0%), the result of the Maki was positive in only 1 (6.7%), and sonication in 5 (33.3%).

Our study shows that both techniques are complementary. We recommend sonicating fragments of the CT from patients with bacteremia of unknown origin and a negative CT culture by the Maki technique.

Introduction

The microbiological diagnosis of colonization of the catheter tip (CT) can be made either by rolling the catheter tip on agar (Maki technique) or by sonication of the distal 4–5 cm segment of the catheter (Maki et al., 1977, Sherertz et al., 1990, Mermel et al., 2009).

Several authors have shown that the Maki technique is appropriate as a standard method for detecting CT colonization (Raad et al., 1992, Sherertz et al., 1997, Bouza et al., 2005, Erb et al., 2014). However, some “multi-lumen” catheters have a vaulted fornix, end at different distances from the CT, and may yield false-negative cultures with the Maki technique. Therefore, an alternative method for CT processing is necessary.

Our objective was to assess the yield of the Maki technique followed by sonication (after slicing) to assess adult CT colonization and catheter-related bloodstream infection (C-RBSI).

Section snippets

Setting

The study was carried out at the laboratory of the Clinical Microbiology and Infectious Disease Department of Hospital General Universitario Gregorio Marañón, Madrid, Spain.

Methodology

We prospectively performed CT cultures of polyurethane central venous catheters (CVCs) from adult patients over a 3-month period. We first performed CT culture by Maki's technique on blood agar plates and then sonicated (1 min + vortexing) small fragments (1 cm) of CVC tips in 5 ml of brain heart infusion (BHI). We cultured 100 μl

Results

We included a total of 252 CVCs, with CT colonization and C-RBSI rates of 14.3% (36/252) and 5.9% (15/252), respectively. Of the 36 colonized CVCs, 21 (58.3%) were detected both by Maki technique and sonication, 6 (16.7%) were detected only by Maki technique, and 9 (25.0%) only by sonication method (Table 1a). Among 15 episodes with concomitant bacteremia, the results for both techniques were positive and concordant in 9 cases (60.0%), positive for the Maki technique in 1 case (6.7%), and

Discussion

Sonication of sliced catheter tips showed a better sensitivity and negative predictive value than the Maki technique for the detection of CT colonization and C-RBSI.

Current international guidelines for the diagnosis of catheter-related infections recommend performing either the Maki technique or sonication for the detection of CT colonization (Mermel et al., 2009). Based on the data from the general population, sonication has not proven to be better than the Maki technique. In addition, it is

Conclusions

We consider that both techniques are complementary. However, in microbiology laboratory routine, we recommend sonication of small fragments of the CT only in patients with bacteremia of unknown origin and a negative CT culture by the Maki technique.

Financial support

M. Guembe (CP13/00268) was supported by the Fondo de Investigación Sanitaria.

Potential conflicts of interest

The authors declare no conflicts of interest.

Acknowledgments

We thank Thomas O'Boyle for his help in the preparation of the manuscript.

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