Thursday, March 6, 2014
In vitro and in vivo investigation of the influence of implant surface on the formation of bacterial biofilm in mammary implants
At least twice a month, PRSonally Speaking posts full abstracts of interesting or potentially controversial articles from a future issue. This 'sneak preview' of a hot article is meant to give you some food for thought and provide you with topic for conversation among colleagues.
When the article is published in print with the April issue, it will be FREE for a period of Two Months, to help the conversation continue in the PRS community and beyond. So read the abstract, join the conversation and spread the word.
This week we present the introduction to "In vitro and in vivo investigation of the influence of implant surface on the formation of bacterial biofilm in mammary implants" by Jacombs et al.
Background: Capsular contracture remains the most common complication following breast augmentation surgery. There is increasing evidence that bacterial biofilm on the implant surface is responsible for initiating inflammation leading to capsular contracture in the majority of cases. We have used pooled data from the in vivo porcine model of capsular contracture to determine if the interaction of bacterial biofilm with smooth and textured implants independently determines progression to capsule formation. In addition, we performed an in vitro experiment to investigate the rate of bacterial growth and adhesion on textured versus smooth implants.
Methods: A total of 16 adult female pigs had 121 breast implants inserted. Of these, 66 implants - 23 smooth and 43 textured - were inoculated with a human strain of Staphylococcus epidermidis and received no other treatment. The implants were left in situ for an average of 19 weeks, after which Baker grading was performed and implants retrieved for analysis. Analysis included scanning electron microscopy (n=66) and determination of the number of infecting bacteria in capsules (n=23) and implants (n=19) by quantitative polymerase chain reaction. For the in vitro analysis 14 sterile
smooth and 14 sterile textured mini implants were incubated separately in 10% tryptone soy broth (TSB, Oxoid) inoculated with 5.8 x 106 colony forming units of S. epidermidis. Samples were removed at 3 time points (2, 6 and 24 hours) for both quantitative bacterial analysis and imaging using confocal laser scanning and scanning electron microscopy.
Results: At explantation, there was no significant difference (p=1.0) in the presence of capsular contracture (Baker grade III and IV) between smooth implants (19/23, 83%) and textured implants (36/43, 84%). Biofilm was confirmed on 60 of the 66 capsules. Capsules from smooth and textured implants had the same number of infecting bacteria (3.01x108/gram for textured versus 3.00x108/gram for smooth). Interestingly, there were 20 fold more bacteria attached to the surface of textured implants when compared
with the surface of smooth implants (1.18x108/gram for textured versus 5.75x106/gram for smooth). For the in vitro analysis, the surface of textured implants showed 11x, 43x and 72x more bacteria at 2, 6, and 24 hours respectively when compared with smooth implants (p<0.001). These findings were confirmed by imaging analysis.
Conclusion: These results show that both in the porcine model of breast implant contracture and in vitro analysis, textured implants develop a significantly higher load of bacterial biofilm in comparison to smooth implants. Furthermore, in vivo, once a threshold of biofilm forms on either smooth or textured implant surfaces, there seems to be an equal propensity to progress to capsular contracture. The significantly higher
number of bacteria attached to the surface of textured implants is a novel finding and further investigation is warranted to delineate the host response to this higher bacterial
load at the implant/tissue interface.
The full article will be published with the April 2014 issue of PRS, and will be free online for non-subscribers. Until then, we hope this "sneak peek" will pique your interests and start a healthy, meaningful conversation.