Bacterial air contamination and the protective effect of coverage for sterile surgical goods: A randomized controlled trial

Background: There is limited knowledge regarding how long prepared sterile goods can wait before becoming contaminated. We investigated whether surgical goods could be prepared the day before surgery and kept sterile overnight in the operating room, if protected by sterile covers.

Methods: Sterile surgical goods for open-heart surgeries (n=70) were randomized to preparation on the morning of the operation or on the previous evening. Exposure time was the total time between preparation and use. Primary outcome was bacterial growth reported as colony forming units (cfu), isolated on 840 agar plates. The protocol was registered with ClinicalTrials.gov (NCT05597072).

Results: When the agar plates were protected with sterile covers, exposure time had no impact (intervention group: 7 cfu, control group: 17 cfu). Without protection, longer exposure time was associated with more cfu (p=0.016). A total of 499 cfu were isolated, displaying 59 different types of bacteria including 13 resistant Staphylococcus epidermidis, 6 (46%) of which were multidrug resistant.

Conclusions: Sterile goods could wait in the operating room for at least 15 hours before use without increased risk of bacterial air contamination, if protected with sterile covers. However, if the goods were not covered, bacterial air contamination occurred over time.