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Sonication is superior to scraping for retrieval of bacteria in biofilm on titanium and steel surfaces in vitro.

Bjerkan G, Witsø E, Bergh K - Acta Orthop (2009)

Bottom Line: Using an in vitro model, we compared 4 methods of biofilm sampling from metal surfaces.Discs of titanium and steel were incubated in the presence of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Propionibacterium acnes in Mueller Hinton broth.Quantitative bacterial cultures were performed for each sampling method.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, St Olav's University Hospital, Trondheim, Norway. geir.bjerkan@ntnu.no

ABSTRACT

Background and purpose: Low-virulence implant infections are characterized by bacterial colonization of the implant with subsequent biofilm formation. In these cases, soft tissue biopsies often prove to be culture negative. Consequently, detachment of the causative adherent bacteria is crucial for correct microbiological diagnosis. Using an in vitro model, we compared 4 methods of biofilm sampling from metal surfaces.

Methods: Discs of titanium and steel were incubated in the presence of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Propionibacterium acnes in Mueller Hinton broth. Non-adherent bacteria were removed by repeated rinsing of the discs. 10 parallels of each disc were subjected to 1 of 4 methods for bacterial recovery: (A) sonication of the discs, (B) scraping of the discs using surgical blades followed by streaking of the blades onto agar plates, (C) scraping of the discs followed by vortex mixing of the surgical blades, and (D) scraping of the discs followed by sonication of the surgical blades. Quantitative bacterial cultures were performed for each sampling method.

Results: With the exception of S. epidermidis on steel, sonication efficiently and reliably dislodged biofilm bacteria. The scraping methods employed did not detach bacteria embedded in biofilm.

Interpretation: Scraping of metal surfaces is not an adequate method for sampling of biofilm bacteria in vitro.

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Arithmetic mean of the number of CFUs cultured after rinsing steps 4, 5, and 6 (final step) in all study groups. For 2 study groups (P. acnes on titanium and steel discs) culture was performed only after the final step due to limited anaerobic culture capacity.
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Figure 0002: Arithmetic mean of the number of CFUs cultured after rinsing steps 4, 5, and 6 (final step) in all study groups. For 2 study groups (P. acnes on titanium and steel discs) culture was performed only after the final step due to limited anaerobic culture capacity.

Mentions: The rinsing procedure efficiently removed non-adherent bacteria (Figure 2). The results were uniform in 7 of the 8 study groups: S. aureus on titanium and steel discs, S. epidermidis on titanium discs, E. faecalis on titanium and steel discs, and P. acnes on titanium and steel discs. Firstly, sonication of discs (method A) allowed retrieval of more bacteria than any of the scraping techniques (p < 0.001, Figure 3). Secondly, the number of CFUs detected after sonication of discs was higher compared to culture of the saline used for the final rinsing step (p < 0.001). Thirdly, all scraping techniques allowed recovery of fewer bacteria compared to the final rinsing step. Finally, only sonication recovered bacteria in 10 of 10 parallels, in contrast to scraping which yielded highly variable results (Table 2).


Sonication is superior to scraping for retrieval of bacteria in biofilm on titanium and steel surfaces in vitro.

Bjerkan G, Witsø E, Bergh K - Acta Orthop (2009)

Arithmetic mean of the number of CFUs cultured after rinsing steps 4, 5, and 6 (final step) in all study groups. For 2 study groups (P. acnes on titanium and steel discs) culture was performed only after the final step due to limited anaerobic culture capacity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823171&req=5

Figure 0002: Arithmetic mean of the number of CFUs cultured after rinsing steps 4, 5, and 6 (final step) in all study groups. For 2 study groups (P. acnes on titanium and steel discs) culture was performed only after the final step due to limited anaerobic culture capacity.
Mentions: The rinsing procedure efficiently removed non-adherent bacteria (Figure 2). The results were uniform in 7 of the 8 study groups: S. aureus on titanium and steel discs, S. epidermidis on titanium discs, E. faecalis on titanium and steel discs, and P. acnes on titanium and steel discs. Firstly, sonication of discs (method A) allowed retrieval of more bacteria than any of the scraping techniques (p < 0.001, Figure 3). Secondly, the number of CFUs detected after sonication of discs was higher compared to culture of the saline used for the final rinsing step (p < 0.001). Thirdly, all scraping techniques allowed recovery of fewer bacteria compared to the final rinsing step. Finally, only sonication recovered bacteria in 10 of 10 parallels, in contrast to scraping which yielded highly variable results (Table 2).

Bottom Line: Using an in vitro model, we compared 4 methods of biofilm sampling from metal surfaces.Discs of titanium and steel were incubated in the presence of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Propionibacterium acnes in Mueller Hinton broth.Quantitative bacterial cultures were performed for each sampling method.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, St Olav's University Hospital, Trondheim, Norway. geir.bjerkan@ntnu.no

ABSTRACT

Background and purpose: Low-virulence implant infections are characterized by bacterial colonization of the implant with subsequent biofilm formation. In these cases, soft tissue biopsies often prove to be culture negative. Consequently, detachment of the causative adherent bacteria is crucial for correct microbiological diagnosis. Using an in vitro model, we compared 4 methods of biofilm sampling from metal surfaces.

Methods: Discs of titanium and steel were incubated in the presence of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Propionibacterium acnes in Mueller Hinton broth. Non-adherent bacteria were removed by repeated rinsing of the discs. 10 parallels of each disc were subjected to 1 of 4 methods for bacterial recovery: (A) sonication of the discs, (B) scraping of the discs using surgical blades followed by streaking of the blades onto agar plates, (C) scraping of the discs followed by vortex mixing of the surgical blades, and (D) scraping of the discs followed by sonication of the surgical blades. Quantitative bacterial cultures were performed for each sampling method.

Results: With the exception of S. epidermidis on steel, sonication efficiently and reliably dislodged biofilm bacteria. The scraping methods employed did not detach bacteria embedded in biofilm.

Interpretation: Scraping of metal surfaces is not an adequate method for sampling of biofilm bacteria in vitro.

Show MeSH
Related in: MedlinePlus