What Is the Duration of Irrigation? An In Vitro Study of the Minimum Exposure Time to Eradicate Bacteria With Irrigation Solutions

Background: Antiseptic irrigation solutions are commonly used by arthroplasty surgeons to reduce intraoperative bacterial colonization with the goal of reducing postoperative infections in the setting of primary total joint arthroplasty. Currently, the minimum irrigation time to eliminate common microbes implicated in periprosthetic joint infection is unknown. We sought to determine the minimum effective exposure time required to prevent growth of Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes with common antiseptic solutions. Methods: S aureus, S epidermidis, and C acnes cultures were treated with povidone-iodine (0.35%), chlorhexidine (0.05%), sodium hypochlorite (0.5%), polyhexamethylene biguanide, and an acetic acid–based solution for 15, 30, 60, 90, and 120 seconds in triplicate. Bacterial growth was quantified using the drop plate method. Failure to eliminate all bacteria was considered “not effective” at that time point. Results: Povidone-iodine 0.35% (Betadine), sodium hypochlorite 0.5% (HySept), and acetic acid (Bactisure) eradicated all bacterial growth after 90 seconds of treatment, and as low as 15 seconds in S aureus and C acnes (Betadine) or S epidermidis (Bactisure). Polyhexamethylene biguanide (Prontosan) required 90 seconds for elimination of S aureus and S epidermidis, and 120 seconds for C acnes. Chlorhexidine 0.05% (Irrisept) did eliminate S epidermidis at 120 seconds but did not effectively eradicate S aureus or C acnes. Conclusion: All tested antiseptic solutions demonstrated successful eradication of all bacterial growth in under 2 minutes of treatment time except chlorhexidine. Povidone-iodine may require the shortest duration of treatment time to successfully eradicate common bacteria.