The Importance of Effective Surface Disinfection
Infectious diseases pose a significant threat to public health, and their prevention and control are critical global challenges. The outbreak of COVID-19 has further highlighted the vital role of disinfection in breaking the transmission chain of infectious diseases. Chemical disinfection remains the most common and effective method for quickly killing or inactivating microorganisms on abiotic surfaces.
Among the various disinfection technologies, hydrogen peroxide (H2O2) has received considerable attention due to its decomposition products – water and oxygen – which do not pose threats to human health or the environment. Hydrogen peroxide has been widely used for disinfecting hospital wards, laboratories, biopharmaceutical facilities, and various biosafety equipment.
Another class of high-efficiency disinfectants are chlorine-based compounds, such as chlorine dioxide (ClO2) and sodium dichloroisocyanurate (DCCNa). These disinfectants effectively destroy a broad spectrum of microorganisms, including bacteria, spores, fungi, viruses, and protozoans. However, their corrosive effects on metals and potential for fabric bleaching and discoloration require careful consideration during application.
While disinfection methods like spraying, fumigation, immersion, and wiping are commonly used, the disinfection efficiency can be influenced by various factors, including the microbial species, surface material and texture, disinfectant susceptibility, temperature, toxicity, and economic constraints. Improper disinfection methods, excessive use, and other issues can lead to resource wastage, health hazards, and environmental pollution. Therefore, it is crucial to evaluate the effectiveness of disinfection practices and understand the disinfection levels in different locations to guide standardized and efficient disinfection protocols.
This study aimed to investigate the disinfection efficiency of commercial hydrogen peroxide products on real field surfaces and provide data to support precise disinfection strategies.
Evaluating the Disinfection Efficiency of Commercial Hydrogen Peroxide Products
The study was conducted according to the Chinese Standard for Evaluating the Efficacy of Disinfection on Site (WS/T 797-2022), with minor adjustments. Three commercial disinfectants were tested: 35% H2O2 solution, 9% ClO2 tablets, and chlorine disinfectant tablets (45% sodium dichloroisocyanurate).
Simulated Field Disinfection
The disinfection efficacy of the three disinfectants was first quantitatively evaluated using simulated field disinfection methods. Indicator cultures of Escherichia coli (ATCC 8099) and Staphylococcus aureus (ATCC 6538) were used to represent gram-negative and gram-positive bacteria, respectively.
The bacterial cultures were applied to the surfaces of horizontal, smooth, flat ceramic tiles, and the disinfectants were sprayed onto the contaminated surfaces. Samples were collected at 15, 30, and 45 minutes after disinfection, and the log10 reduction of the bacterial indicators was calculated.
Key Findings:
- All three disinfectants were effective against E. coli and S. aureus, achieving a reduction of more than 3.00 log10 colony-forming units/mL after a 15-minute exposure.
- The disinfection efficacy was significantly affected by the exposure time, with the 45-minute exposure showing higher reductions compared to the 15-minute exposure.
Field Disinfection Evaluation
The effectiveness of the disinfectants was also evaluated in a food production and processing workshop and a biosafety level 2 laboratory, using natural bacteria and molds as microbial indicators.
Food Production and Processing Workshop
- The natural bacterial load in the workshop decreased by more than 90% when using 10.5% hydrogen peroxide with a 30-minute exposure time.
- Lower concentrations of hydrogen peroxide (3.5% and 7%) did not achieve the minimum 90% killing percentage, even with longer exposure times.
Biosafety Level 2 Laboratory
- Chlorine dioxide at 500 mg/L and 60 minutes of exposure, as well as sodium dichloroisocyanurate at 450 mg/L and 60 minutes of exposure, achieved a killing percentage of over 90% for the natural bacteria and molds.
- Lower concentrations and shorter exposure times for these disinfectants were not as effective, with killing percentages below 90%.
Factors Influencing Disinfection Efficiency
The study revealed that the disinfection efficiency of the tested products was influenced by several factors:
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Disinfectant Concentration: Higher concentrations of the disinfectants, such as 10.5% hydrogen peroxide, were required to achieve the minimum 90% killing percentage in environments with a high organic load and microbial burden.
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Exposure Time: Longer exposure times, up to 60 minutes, were necessary to reach the desired disinfection level, especially for chlorine dioxide and sodium dichloroisocyanurate.
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Surface Characteristics: The rough, nutrient-rich surfaces in the food production workshop presented a greater challenge for disinfection compared to the smoother surfaces in the biosafety laboratory.
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Microbial Load: Environments with a higher natural bacterial and mold load, such as the food production workshop, required more potent disinfection strategies to reach the target disinfection level.
Selecting the Appropriate Disinfectant
The choice of disinfectant should be based on the specific needs and conditions of the environment:
- Hydrogen Peroxide: Suitable for disinfecting surfaces in the food industry, animal breeding, and various biosafety equipment due to its broad-spectrum antimicrobial activity and environmental-friendliness.
- Chlorine Dioxide and Chlorine-Containing Disinfectants: Effective for disinfecting contaminated surfaces, water, fruits, vegetables, and food/beverage utensils. However, their corrosive and irritating properties require careful consideration, especially for metal objects and colored fabrics.
- Chlorine-Containing Disinfectants: Highly suitable for environments with a high microbial load, complex components, and fewer personnel, such as open outdoor environments and waste-disposal sites. However, they can cause damage to surfaces and discomfort due to their irritating odor.
Proper surface cleaning before chemical disinfection is essential to ensure the effectiveness of the process. Disinfection strategies should be carefully evaluated and adjusted based on the specific environmental conditions, microbial load, and safety considerations to achieve the desired level of disinfection while minimizing resource wastage, health hazards, and environmental pollution.
Conclusion
This study provides valuable insights into the disinfection efficiency of commercial hydrogen peroxide products and other commonly used disinfectants. The findings highlight the importance of considering factors such as disinfectant concentration, exposure time, surface characteristics, and microbial load when developing effective disinfection strategies.
By understanding the specific requirements for different environments and the performance of various disinfectants, stakeholders can make informed decisions to implement precise, standardized, and efficient disinfection protocols. This approach can help break the transmission chain of infectious diseases, protect public health, and promote sustainable sanitation practices.
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