The Effect of Organic Soil Load on the Virucidal Efficacy of a Disinfectant Utilizing Duck Hepatitis B Virus and Human Immunodeficiency Virus (HIV)

Background: Ortho-phthalaldehyde (OPA) has emerged since 2000 as the new alternate high-level disinfectant for reprocessing medical devices.  Virus inactivation studies were performed using duck hepatitis B virus (a surrogate for human hepatitis B) and human immunodeficiency virus (HIV) exposed to diluted OPA solution with soil loads added.

Objective: To evaluate the effect of organic soil type and/or concentration on the virucidal efficacy of dilute OPA.  

Methods: Organic soil (either duck serum, human whole blood, or fetal bovine serum at differing concentrations) was incorporated into each virus inoculum.  Films of virus were prepared by spreading 0.2 mL of virus inoculum uniformly over the bottom of a 100 x 15 mm sterile glass petri dish, and air-dried at 10-30°C until visibly dry.  The dried film with soil was exposed to 2 mL of diluted OPA for 5 minutes at 50-52.5°C.  Following exposure time, each plate was scraped with a cell scraper to resuspend the contents and the virus-disinfectant mixture was immediately passed through individual Sephadex columns to separate the virus from the disinfectant.  The filtrates were then titered by serial dilution and assayed for infectivity and cytotoxicity.

Results: All studies demonstrated at least a 3-log reduction of viral titer.

Conclusions: The origin and concentration of organic soil load did not adversely affect the efficacy of the disinfectant.  The results of each virus type, duck hepatitis B and HIV, have similar log reductions of viral titer regardless of the soil load type and concentration.