Nano-TiO2-based photocatalytic disinfection of environmental surfaces contaminated by meticillin-resistant Staphylococcus aureus

Background: Traditional cleaning and disinfection methods are inefficient for complete decontamination of hospital surfaces from meticillin-resistant Staphylococcus aureus (MRSA). Additional methods, such as nano-TiO2-based photocatalytic disinfection (PCD), could be helpful. Aim: To evaluate anti-MRSA activity of PCD on polyvinyl chloride (PVC) surfaces in naturallike conditions. Methods: Two identical PVC surfaces were used, and nano-TiO2 was incorporated into one of them. The surfaces were contaminated with MRSA isolated from hospitalized patients using a mist sprayer to simulate the mode of environmental contamination caused by a carrier. MRSA cell density was assessed before contamination until 180 min after contamination using Rodac plates. The differences between test and control surfaces in terms of MRSA density and log MRSA density reduction were assessed using parametric and non-parametric statistical tests. Five strains were tested, and each strain was tested five times. Findings: The highest median MRSA densities [46.3 and 43.1 colony-forming units (cfu)/ cm2 for control and test surfaces, respectively] were detected 45 min after contamination. Median MRSA densities 180 min after contamination were 10.1 and 0.7 cfu/cm2 for control and test surfaces, respectively (P<0.01). Log MRSA density reduction attributable to PCD was 1.16 log cfu/cm2 , corresponding to 93% reduction of the baseline MRSA contamination. Conclusions: The disinfectant activity remained stable throughout the 25 testing occasions, despite between-test cleaning and disinfection. The anti-MRSA activity of PCD was compatible with the benchmark for surface hygiene in hospitals (<1 cfu/cm2 ), but required 3 h of exposure to photocatalysis. Thus, PCD could be considered for non-clinical surfaces. However, for clinical surfaces, PCD should be regarded as supplemental to conventional decontamination procedures, rather than an alternative.