Targeted Swabbing of Implant-Associated Biofilm Formation-A Staining-Guided Sampling Approach for Optimizing Routine Microbiological Diagnostics.

Sylvio Redanz,Andreas Podbielski,Andreas Enz,Philipp Warnke

doi:10.3390/diagnostics11061038

Sylvio Redanz, Andreas Podbielski + Show 2 more

Open Access

https://doi.org/10.3390/diagnostics11061038

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Abstract

Background: Swabbing of implants removed from potentially infected sites represents a time saving and ubiquitously applicable alternative to sonication approaches. The latter bears an elevated risk of processing related contaminations due to the high number of handling steps. Since biofilms are usually invisible to the naked eye, adequate swabbing relies on the chance of hitting the colonized area on the implant. A targeted directed swabbing approach could overcome this detriment. Method: Three dyes were tested at different concentrations for their toxicity on biofilm-associated cells of S. epidermidis, the species most frequently identified as a causative agent of implant-associated infections. Results: Malachite green (0.2%) delivered the highest bacterial recovery rates combined with the best results in biofilm visualization. Its suitability for diagnostic approaches was demonstrated for smooth and rough implant surfaces. Biofilm-covered areas were successfully visualized. Conclusion: Subsequent targeted swab-sampling resulted in a significantly increased bacterial recovery rate compared to a dye-free “random swabbing” diagnostic approach.

Highlights

Implant-associated infections are a worldwide problem often traced back to biofilm formation started by single, surface colonizing and thereafter biofilm-forming bacteria
Malachite green is recommended to be used as a 2% (w/v) [20] solution for optimal biofilm staining
The absence of staining artefacts was evaluated by testing biofilm-free discs in the same manner as biofilm bearing discs; none of the tested staining solution resulted in unspecific coloration of the biofilm carrier itself

Summary

Introduction

Implant-associated infections are a worldwide problem often traced back to biofilm formation started by single, surface colonizing and thereafter biofilm-forming bacteria. Since such biofilm-organized bacteria are extremely resistant to host defence mechanisms as well as to antibiotic treatment [1], it is crucial to prevent this initial colonization step and to allow for a fast incorporation of the prosthesis into the host tissue. Swabbing of implants removed from potentially infected sites represents a time saving and ubiquitously applicable alternative to sonication approaches. The latter bears an elevated risk of processing related contaminations due to the high number of handling steps. Conclusion: Subsequent targeted swab-sampling resulted in a significantly increased bacterial recovery rate compared to a dye-free “random swabbing” diagnostic approach

Methods

Results

Conclusion