Does local infiltration analgesia in total joint arthroplasty offer any protection from prosthetic joint infections? An invitro experimental study.

Many local anaesthetic agents are now reported to have anti-microbial properties in various studies, and this ability to inhibit microbial growth is not uniform. As local anaesthetics are commonly infiltrated into the surgical field for perioperative pain management, it is very important to know if this practice offers any protection against surgical site infections.


METHODS
In this study, three of the most common prosthetic joint infection-causing organisms, namely, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, were chosen and tested against the commonly used local anaesthetics. The suspension of each organism was inoculated onto three different Mueller-Hinton agar plates and a drop of an undiluted solution of each local anaesthetic agent is inoculated onto one of the three culture plates; vancomycin and gentamicin discs were used as controls.


RESULTS
The local anaesthetic agents tested could not inhibit the growth of any of the microorganisms. As there was no inhibition of bacterial growth in the experiment with the above three agents, further experiment with a diluted mixture was not performed.


CONCLUSIONS
It can be concluded that local infiltration of anaesthetic agents is less likely to provide any perioperative protection against prosthetic joint infections but may interfere with some diagnostic tests for microbiology.