Initial adhesion of methicillin-sensitive and methicillin-resistant Staphylococcus aureus strains to untreated and electropolished surgical steel drill bits

Abstract

Electropolishing of stainless steel has been thoroughly investigated as a prophylactic measure to prevent bacterial colonization of orthopaedic implants and infection. Initial bacterial adhesion onto surgical drill bits as a possible factor for orthopaedic surgical site infections has not yet been documented. The present study investigated the influence of electropolishing on initial staphylococcal adhesion onto AISI 440A stainless steel drill bits. Specifically, one methicillin-susceptible standard laboratory Staphylococcus aureus type strain (DSM 20231T), one methicillin-resistant S. aureus reference strain (DSM 46320) and one methicillin-resistant clinical isolate from an infected orthopaedic implant were used. After standard sterilization, drill bits were immersed in the respective bacterial suspension; bacteria adherent to surface were harvested by vortexing the drill bits in phosphate-buffered saline and viable counts of bacteria transferred from the suspension were made (transferred to log10 for further analysis). Electropolishing significantly reduced adhesion of the clinical S. aureus strain and the S. aureus DSM 20231T. However, electropolishing significantly increased adhesion of the S. aureus DSM 46320. These results show that electropolishing significantly influences initial adhesion of S. aureus strains to surgical drill bits and that the nature of this influence depends on the S. aureus strain examined. For a general recommendation of electropolishing drill bits and guidelines for their handling during surgery, further studies with more strains isolated from infected wounds are suggested.