The challenges of the past: Staphylococcus aureus decolonisation and antimicrobial prophylaxis in elective vascular procedures

Kaitlyn L. De Koning

BPharm (Hons) | Clinical pharmacist, Fiona Stanley Hospital

[Pharmacy GRIT article no: 20251414]

Staphylococcus aureus (S. aureus) remains a prevalent pathogen responsible for surgical site infection (SSI), accounting for more than a third of cases.1 Carriers of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) are nine and fourteen times more likely, respectively, to develop a SSI compared to non-carriers.2, 3 A study conducted by Perl et al. uncovered that patients who acquired a S. aureus SSI, had identical paired isolates from the nares 85% of the time.4 The Australian Therapeutic Guidelines recommend preoperative screening and decolonisation for patients undergoing arthroplasty procedures or cardiothoracic procedures involving sternotomy.5 However, there is less evidence available to support this practice for other surgical populations.5

After reviewing relevant literature, I determined that studies conducted within the vascular population have generally consisted of lower quality trials and demonstrated varying levels of statistical significance. As such, a retrospective, local audit of 54 elective vascular procedures was conducted to assess the impact of S. aureus colonisation on SSI rates and evaluate the potential benefit of preoperative screening, decolonisation, and antimicrobial prophylaxis. For the purposes of this audit, endovascular procedures were excluded. This study was undertaken by a small team; I acted as the primary researcher, in collaboration with the antimicrobial stewardship pharmacist and infectious diseases consultant, who both provided guidance and oversight throughout the project.

Upon reflection, it became clear that our study was influenced by limiting factors inherent in the chosen audit methodology. As this was a retrospective audit, not all patients were screened preoperatively to accurately assess colonisation status. This prevented us being able to determine a direct relationship between colonisation and SSI rates. The retrospective nature of this study was again problematic as it was determined there was likely an incomplete reporting of SSIs, as we relied solely on data documented during the patient's hospital admission. This approach would not have captured any patients who presented to their GP after discharge to manage signs and symptoms of infection. Therefore, if I were to undertake a similar project in the future, I would consider implementing a prospective study design. Firstly, this would ensure appropriate pre-screening protocols were applied, allowing us to determine a stronger relationship between colonisation and the incidence of SSIs. Secondly, this would allow us to standardise outcome measures, ensuring consistent and reliable follow up to provide an accurate overview of SSI rates.

Throughout this experience I developed valuable skills in research techniques, data collection, data analysis, and presentation of data and results. I navigated multiple databases to conduct a comprehensive literature review, which allowed me to formulate a suitable research question. Given the retrospective study design, I was able to gather a substantial dataset within the time allocated for the project. This required me to utilise effective data collection tools and methods to facilitate efficient analysis and interpretation. Additionally, I had the opportunity to collaborate closely with the antimicrobial stewardship pharmacist and infectious diseases consultant, gaining valuable insights from their expertise.

Further high-quality research is required in this patient cohort to confirm the correlation between S. aureus colonisation and SSI rates. Once this relationship is established, additional considerations, including implementation strategies and a cost-benefit analysis, will be necessary to evaluate the suitability of routine screening and decolonisation.

References

  1. Inui T, Bandyk DF. Vascular surgical site infection: risk factors and preventive measures. Semin Vasc Surg 2015; 28: 201–207.
  2. Perl TM. Prevention of Staphylococcus aureus infections among surgical patients: beyond traditional perioperative prophylaxis. Surgery 2003; 134 (5_Suppl): S10–S17.
  3. Kavanagh KT, Abusalem S, Calderon LE. View point: gaps in the current guidelines for the prevention of Methicillin-resistant Staphylococcus aureus surgical site infections. Antimicrob Resist Infect Control 2018; 7: 112.
  4. Perl TM, Cullen JJ, Wenzel RP, Zimmerman MB, Pfaller MA, Sheppard D, et al. Intranasal mupirocin to prevent postoperative Staphylococcus aureus infections. N Engl J Med 2002; 346: 1871–1877.
  5. Therapeutic Guidelines. Preventing postoperative Staphylococcus aureus infections [updated August 2022]. North Melbourne: Therapeutic Guidelines Limited; 2019.

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