I want to do a long-term bacterial testing for orthopedic implant to determine if my antibacterial coated external fixation is capable of prolonging bacterial formation.
What I am stuck on is how to prepare the system. I am testing for at least 1 month-worth of implantation. I do not know if I should replace the broth daily or leave it until the desired date.
I fear that if I just leave it alone, bacteria will die due to lack of food, but replacing daily with a new batch of bacteria + broth seems like over-addition of bacteria from the designated initial bacteria CFU.
Most article I saw did not go beyond 2-3 days. I am not sure if I am just searching the wrong keywords.
Most important issue with implants are forming biofilm of bacteria on them, so I think first of all you must check your agent against biofilms of bacteria, then choosing animal model for your purpose.
That is my idea.
Try to simulate the in vivo situation. You keep the initial inoculum of bacteria fixed and replenish them with new media i.e. provide a continuous culture system.
Dear all,
I must apologize for forgetting to mention the most crucial part. I am not doing this in vivo but in vitro.
I want to simulate a situation in which the external fixator is fixed into a bone whereas the screws part is in the bone and the cylindrical part is surrounded by muscle/blood.
My plan was to immerse the fixator into a media containing an initial inoculum of bacteria and determine how long can the prolonged release of antibacterial agent inhibit bacterial growth. As such, why I was thinking about performing a long term experiment. From my search, external fixator normally stay in the body for at least 3-4 weeks which is why I chose this range.
Initially, I was thinking leaving the fixator inside the media until the desired date. However, I ran into the problem of not knowing if bacteria will survive without constant replenishing of media.
Therefore, I decided to change my plan to changing it everyday, but then I don't know how to exactly change it while maintaining the initial bacterial amount as the fixator will be transferred into a new media.
Hence, I was thinking of preparing the new media containing the initial bacteria amount and replace that daily. Aside from the possible bacteria adhesion on the surface, it will keep the bacteria amount pretty consistent and might be easier to evaluate.
I want to simulate the situation in vitro to avoid the more expensive in vivo. I think this method may work although now that I think about it more, it is impossible to maintain them for a month while keeping its concentration constant, no matter what I do.
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