Perioperative Strategies to Prevent Surgical Site Infection After Shoulder Surgery

Abstract: In Sweden, about 18 000 patients undergo shoulder surgery each year. The current surgical site infection (SSI) rate after planned shoulder surgery is 0,3-5 %, which means that approximately 300 people are affected each year in Sweden. Treatment of deep SSIs always involves at least one reoperation followed by long-lasting treatment with antibiotics. In addition to pain and reduced mobility, an SSI can also have a negative effect on mental health. It is not possible to pinpoint exactly what causes an SSI. However, in today´s modern operating theatres with ultra clean air, tightly woven gowns, and surgical practice that strictly adheres to aseptic guidelines, SSIs after orthopaedic surgery are predominately caused by bacteria from the patient’s skin.The aim of this thesis was to evaluate perioperative strategies to prevent surgical site infection after shoulder surgery, focusing on bacterial burden on the skin. Cutibacterium acnes (C. acnes), a skin commensal, thrives in the sebaceous glands and causes most infections after shoulder surgery. Despite strict standardised preoperative preparation with 0.5% chlorhexidine solution in 70% ethanol, studies have shown that C. acnes are only partially eradicated. Topical treatment with benzoyl peroxide (BPO) over several months has been used to treat acne vulgaris for more than 50 years.In two randomised studies, we compared prophylactic topical treatment with BPO (applied five times over a period of 48 hours before surgery), with a control group with no BPO treatment. In the BPO group, the burden of C. acnes prior to incision and at the end of the surgery decreased significantly.When studying the effects of skin preparation, the technique and method used to capture the microbiome while maintaining the skin’s barrier, is crucial. In a pilot study, we developed a novel Pencil Eraser Swab-technique (PES) and compared this with two established swab techniques. The PES-technique was found to be significantly better, both in terms of sensitivity in detecting C. acnes and in quantification of viable bacteria.Following closure of a surgical incision, the wound is re-epithelialised within 24-72 hours. Choice of dressing is usually a question of personal preference and tradition rather than evidence based. The degree of colonisation of bacteria beneath wound dressings with different occlusive properties is not known. To investigate this, we compared three wound dressings of varying permeability on healthy skin. After 48 hours we found that recolonisation of bacteria was significantly higher beneath the semipermeable and occlusive wound dressings, than beneath the airy (gauze) dressing.Perioperative reduction of the bacterial burden on the skin is important in the fight against surgical site infection. A reliable technique to capture bacteria is essential when evaluating different methods.