Measurement and evaluation of microbial contamination during orthopedic implant surgery

Examensarbete för masterexamen
Stålfelt, Frans
Background: According to the Swedish Association of Local Authorities and Regions, the cost for society related to healthcare-associated infections (HAI) is estimated to be 6.5 billion SEK annually. Furthermore, the cost is expected to increase, due to an aging and growing population and the increase in antimicrobial resistance. HAIs affect 1 out of 10 patients, were surgical site infections (SSI) is the second most common HAI, after catheter related urinary tract infections. If correct precautions are performed, 30-50% of HAIs can be prevented. By measuring bacteria levels inside the operating room (OR) and analyzing the correlation to contamination of the surgical wound, the project Clean Care aims to investigate risk factors and transmission pathways for SSI. Purpose and objectives: The purpose of this thesis is to gather knowledge and deeper understanding of contamination pathways that may cause SSI. The objective is to gather data from measurements during ongoing surgeries in order to evaluate contamination pathways, such as direct airborne contamination, indirect contamination via the surgical instruments and endogenously contamination from the patient’s own skin where the incision is going to be. Method: Measurements were performed during ongoing hemiarthroplasty femoral neck fracture orthopedic surgeries in ORs equipped with either a conventional ventilation system (n=10), conventional ventilation system with mobile laminar airflow units (n=3) or laminar airflow ventilation system (n=11). The measurements were conducted via active air sampling through gelatin-filters with a Satourios MD8 device, surface sampling from instrument tables and sampling from the skin and wound collected with flocked nylon swabs. Bacterial samples were grown on agar for enumeration and determining of specie, both aerobic and anaerobic. Results and conclusions: A statistically significant higher number of bacterial-carrying particles was found in the air of the conventionally ventilated OR compared to the OR equipped with laminar airflow ventilation (p<0.001). No significant correlation between the amount of airborne contamination (direct or indirect) and contamination of the surgical wound could be seen. However, trends suggest that endogenously contamination is an influencing factor of wound contamination (R2 = 0:8071). Due to too few measurements, no statistical analysis could be performed on the influence of the mobile laminar airflow units on bacterial contamination.
Healthcare Associated Infections, Surgical Site Infections, Colony Forming Units, Postoperative Implant Related Infections, Medical Devices, Biomedical Engineering
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