Abstract
The use of sub-lethal doses of cell wall active antibiotics to induce cell wall deficiency in S aureus has been described. Cell Wall Deficient S aureus show an increased in-vitro ability to form biofilm. Cephalosporins(cell wall active antibiotics.) are commonly used at time of arthroplasty surgery as antimicrobial prophylaxis. Adherence is fundamental step in biofilm formation.
The adherence of cell wall deficient S aureus versus ‘wild type’ S aureus to glass was investigated. Slides comparing the two types of organisms were analysed using fluoroscopy and J-image software. The ability to adhere to plastic was investigated using a micro-titre based absorption test. In a third investigation a centrifugal force was used to quantify the adherence ability of the cell wall deficient organisms to the glass slides.
The cell wall deficient organisms demonstrated an increased ability to adhere to glass compared to the ‘wild type’. After exposure, there was on average twenty times more cell wall deficient organisms per unit area compared to the ‘wild-type’. The micro-titre plates were similar. After incubation, the absorption of each well was measured. Compared to the ‘wild type’ there was a significantly increased absorption in wells containing the cell wall deficient organisms. Showing an increased ability to adhere to plastic. The third technique quantified the ability to adhere using a centrifugal force. The slides were exposed to ‘wild type’ and cell wall deficient organisms, however before staining they were placed in a centrifuge. On analysis there were five cell wall deficient S aureus per field of view, compared to 0.5 ‘wild-type’.
An increased ability of cell wall deficient S aureus to adhere to surfaces has been shown. Adherence is fundamental to biofilm formation. The significance to orthopaedics is that the inadequate use of Cephalosporins at time of operation may be facilitating chronic infections.
Editoral Secretary Mr Peter Howard. Correspondence should be addressed to BHS at the Royal College of Surgeons, 35 - 43 Lincoln’s Inn Fields, London WC2A 3PN.
