P-1093. Role of antiseptic formulation/treatment protocols in reduction of S. aureus colonization on ex-vivo porcine tissue model

Abstract Results SNA showed persistent bactericidal activity ( > 5.5 log reduction compared to saline) at all time points from 1 hour to up to 5 days (1-10 treatments) with explants inoculated with MRSA (106CFU/mL). In addition, SNA had a statistically significant greater log reduction compared to all other antiseptic treatments at 24 hours and 3 days and mupirocin treatment at 3 days. At 5 days, SNA was not statistically different from Nozin® and mupirocin. The mean recovery of saline for 24 hours, 3 days and 5 days was ∼5x107 CFU/mL (see Figure 1). Conclusion This study highlights the role of the antiseptic formulation/ treatment protocols for antimicrobial efficacy. Not all antiseptics provide immediate and continued antimicrobial efficacy. Disclosures Ranjani Parthasarathy, Ph.D., Solventum: Employee|Solventum: Stocks/Bonds (Public Company) Shazia Siddiqui, MS, RM(NRCM), Solventum: Grant/Research Support Isaac Salvatierra, MB (ASCP), Solventum: Grant/Research Support Marnie Peterson, PharmD, PhD, Solventum: Advisor/Consultant Background Recently, a study found that a nasal Iodophor antiseptic did not meet the criteria for noninferiority compared to nasal mupirocin antibiotic in reducing Staphylococcus aureus clinical cultures among adult ICU patients undergoing daily CHG bathing (Huang et al., JAMA, 330, no. 14 [2023]: 1337). An ex-vivo tissue model was created to test the efficacy of commercially available povidone iodine and alcohol based nasal antiseptics compared to mupirocin for one or more treatments. Methods Porcine mucosal tissue explants (5 mm) were placed on culture inserts incubated with media and infected with methicillin-resistant S. aureus (MRSA) Xen30 to achieve 10⁶ CFU/explant. After 2 hour incubation, explants were treated by swabbing with antiseptic formulations (3M™ Skin and Nasal Antiseptic (SNA), Betadine® Antiseptic (10% Povidone Iodine), Profend™ and Nozin® Popswab® brands) per manufacturer’s instructions, rinsed with mucin after 1 hour and incubated for 1 hour or 24 hours at 37 °C. For the 3-day and 5-day study, explants were swabbed twice daily with antiseptic and mupirocin treatments, followed by mucin rinsing. Infected explants were collected, treated with neutralizing solution, vortexed, sonicated, and plated.