Wound infection following Hepatopancreatobiliary (HPB) surgery – a measure of predictive surgical and transmission factors and patient outcomes

Chambers, Lucy Emma (2023) Wound infection following Hepatopancreatobiliary (HPB) surgery – a measure of predictive surgical and transmission factors and patient outcomes. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Incidence of surgical site infections (SSIs) following hepatopancreatobiliary (HPB) surgery can be as high as 20 – 40 %. SSIs, particularly those caused by antimicrobial resistant (AMR) organisms, are a significant burden for both patients and the NHS. The aim of this study was to determine risk factors, incidence and the source of these infections and to measure how bacteria that can cause SSIs can form biofilms. Patients’ surgical sites were swabbed before and after surgery as well as different surfaces on the HPB ward. The bacteria were identified and their AMR was determined. Patient demographics, comorbidities and full blood counts were analysed to determine risk factors associated with SSIs. Biofilm assays (crystal violet, XTT and bacterial percentage coverage), using three of the isolates found on patients (Enterobacter cloacae, Enterococcus faecium and Staphylococcus haemolyticus) were conducted. The incidence of SSIs was 23.1 % and risk factors identified included bile leak, use of drains, pancreatic surgery, open surgery, long surgery and long hospital stay. Statistical analysis showed poor post-operative nutrition, post- operative pneumonia and return to the operating theatre as being significant risk factors for SSI. The bacteria found to cause SSIs were all gut commensals that were isolated from the drain fluid and not from the wound swabs, suggesting transmission occurred during surgery. High levels of multi-drug resistant (MDR) and extensively drug resistant (XDR) species were isolated, particularly XDR coagulase negative staphylococci. The surfaces with the most MDR and XDR species included most of the bathroom surfaces, the nurses’ phone and computer keyboard, bedside cabinet and the soap dispenser. In vitro biofilm assays showed that AMR could develop among bacteria in a polymicrobial biofilm and this could therefore occur within a polymicrobial SSI and hospital setting, making treatment more difficult. It is clear that more needs to be done to prevent SSIs following HPB surgery and that the hospital can still act as a reservoir for MDR and XDR bacteria.