A Multi-level Antimicrobial Surface Coating for a Healthier Environment

• A multi-level antimicrobial coating was produced in the Hong Kong University of Science and Technology (HKUST) laboratory using the newly developed staged flow micromixing to prepare contact-killing and anti-adhesion coating made of US-FDA approved polymeric materials. The process was optimized to scale-up the production to 5 liters per hour. 300 liters of the multi-level antimicrobial coating was prepared for the study for a total of 24 weeks as three liters of the coating was needed for one patient privacy curtain.
• The study was conducted in the rehabilitation ward of the Kowloon Hospital including both male and female cubicles. It was carried out in three stages with each stage consisting of survey and a four weeks' observation period, separated by three weeks' washout period. In the rehabilitation ward of Kowloon Hospital, a set of male and female cubicle was recruited for the study after getting maximum number of bacterial contamination on patient privacy curtains in pilot study of 8 weeks. Each cubicle had 12 curtains besides admitted patients where all the samples are collected.
• Environmental sampling was carried out using sponge swab on the surfaces of the patient privacy curtains. The total bacteria count and quantitative isolation of MRSA was done using established protocols. The total bacteria count provides a quantitative measure of surface cleanliness, while the methicillin-resistant Staphylococcus aureus (MRSA) count was indicative of the risk of contact transmission from contaminated surfaces. 2-4 weeks survey provided control data on the cleanliness of patients privacy curtains in terms of total bacteria and MRSA counts.

During the study period, the Kowloon Hospital/Queen Elizabeth Hospital infection control team monitored MDROs regularly as part of their routine operation. The procedure and schedule was followed strictly the infection control protocol. All infection control measures implemented after isolation of MDROs were followed according to the hospital's usual practice as advised by the infection control team. In the study, the identification of the organisms in patients more than 48 hours after admission without prior isolation of the organisms in clinical or screening specimens was defined as nosocomial.

• The investigators demonstrated a cross-over intervention study. In the first stage of study, half of the patient privacy curtains were considered as treatment (antimicrobial coated) and the other half of the curtains as control in the same setting in a cubicle. As the study was double blind, so coding was done to identify the treatment as control curtains.
• Sample were taken from eight highly touched areas of 50x50 cm² on weekly bases for three consecutive weeks on 7th day of first installation. On each period/phase 480, 576 and 786 samples were collected accordingly using the developed sample protocol. In total, the investigators collected 1824 samples from 76 patient privacy curtains in which 912 (50%) were control curtain and 912 (50%) are antimicrobial coated curtains.
• Healthcare workers from the participating wards were assessed for their acceptance of the multilevel antimicrobial disinfectant coating by way of a questionnaire. Additional reformulation may be necessary to increase the acceptability of the coating technology to the healthcare workers.
• For the bacteria count, duplicate plates of tryptic soy agar (TSA) for total bacteria count and Chromagar MRSA (selective agar for MRSA detection) were used for enumeration. CFU/m² is calculated after 48 hours incubation at 37°C. Data was analyzed using Statistical Package for the Social Sciences (SPSS) V.25 to assess the effectiveness of the coating in reducing the contamination level of the surface. The total bacteria count on the patient privacy curtains was compared between the control and treatment group using Mann-Whitney test and T-test. ANOVA analysis allowed the comparison of different periods of study of phase wise as well as week wise. The significance of the statistical test is defined to have a P value <0.05.

Inclusion criteria

• A convalescence ward with reasonable amount of nursing activities
• No recent history of outbreaks of communicable diseases in the wards

Exclusion criteria

• Wards with little nursing activities including infirmary wards
• Wards with frequent outbreaks which lead to excessive curtain changes