Efficacy of three disinfectant formulations and a hydrogen peroxide/silver fogging system on surfaces experimentally inoculated with meticillin-resistant Staphylococcus pseudintermedius.

Abstract

BACKGROUND: Effective environmental disinfection is necessary to prevent nosocomial infections from meticillin-resistant Staphylococcus pseudintermedius (MRSP). However, there are currently no commercial disinfectant sprays or fogging systems with label claims against MRSP. HYPOTHESIS/OBJECTIVES: To evaluate the efficacy of a quaternary ammonium product (QAC), an accelerated hydrogen peroxide product (AHP), a hydrogen peroxide and silver product (HAL), and a hydrogen peroxide and silver fogging system (FOG) against MRSP. METHODS AND MATERIALS: Sterile plastic surfaces inoculated with MRSP were treated with 200&#xa0;&#xb5;L of QAC, AHP or HAL for the recommended contact times. For FOG, inoculated samples were placed in eight positions within a sealed room before fogging for the recommended contact time. Post-treatment bacterial counts were compared to untreated positive controls. Sterile uninoculated surfaces served as negative controls. RESULTS: Least-squares mean reduction (log) in colony forming units (cfu) was 3.55 logfor QAC (P&#xa0;<&#xa0;0.0001), 3.60 logfor AHP (P&#xa0;<&#xa0;0.0001), 1.66 logfor HAL (P&#xa0;<&#xa0;0.0001) and 0.32 logfor FOG (P&#xa0;=&#xa0;0.004). QAC, AHP and HAL reduced MRSP cfu by 99.97%, 99.98% and 97.81%, respectively. FOG reduced cfu by 52.14%. CONCLUSIONS AND CLINICAL IMPORTANCE: QAC and AHP effectively disinfected surfaces inoculated with MRSP. Although HAL provided lower MRSP reduction, it may be considered clinically acceptable. FOG as a sole means of MRSP disinfection was not supported yet may have utility as an adjunctive disinfectant in clinical areas with bacterial densities lower than our experimental inoculum.