CuO, TiO ₂ and ZnO nanoparticles for disinfecting contaminated hospital surfaces

Nosocomial infections are infections that are transmitted to people due to hospital admission and medical procedures and usually happen 48 to 72 hours after patient admission and lead to the dissemination of these infectious agents in the society. In this study the various bacteria on the floor, walls and beds of the Afzalipour hospital, Kerman, Iran were determined and the effect of the CuO, Ti0 ₂ and ZnO nanoparticles on these bacteria was investigated. Two hundred and ten (210) samples were taken from the floor, walls and beds of the Afzalipour hospital during 7 months. The samples were transferred to the culture medium, Nutrient Agar. In order to determine the bacteria type, specific culture media and biochemical tests were used. After the type of the bacteria was determined, a uniform suspension of the bacteria with certain density was prepared. Then the suspensions were added to culture mediums containing certain concentrations of nanoparticles and were incubated under proper conditions. The efficacy of the different nanoparticles was determined based on comparing the different growth rates of colonies in the control and the experimental media. The majority of bacteria recognized in this study were Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. Results showed that ZnO at the concentration of 1500 mg/L can eliminate Staphylococcus aureus and Escherichia coli by 100% and at the concentration of 4000 mg/L can eliminate Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa by 100% and CuO at the concentration of 4000 mg/L can decrease the density of Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa by 98%. For Ti0 ₂ at 4000 mg/L concentration the bacteria elimination rate for Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli was 100%, 55%, 80% and 59% respectively. According to these results, the highest antibacterial effect belonged to ZnO, CuO and Ti0 ₂ respectively. The most resistant bacteria to the CuO, ZnO and Ti0 ₂ nanoparticles were Bacillus subtilis, Pseudomonas aeruginosa and Bacillus subtilis respectively. The most sensitive bacteria to all three nanoparticles were gram positive Staphylococcus aureus.