Commercial Disinfectants Demonstrate Significantly Greater Efficacy than Natural Alternatives

William A. Rutala, Ph.D. and David J. Weber, M.D.
University of North Carolina at Chapel Hill

It has been estimated that foodborne illness results in more than 30 million infections and 9,000 deaths each year in the United States. Mechanisms of acquisition of foodborne pathogens include ingestion of contaminated raw fruits and vegetables, inadequate cooking of contaminated produce or meats and direct contact with contaminated surfaces. Because pathogens can be transferred from surfaces to humans, thereby causing illness, the importance of proper surface disinfection to decrease the number of contaminants should not be underestimated.

Numerous studies have shown that proper disinfection of surfaces decreases or eliminates potential pathogens. Many commonly used hospital and household disinfectants effectively eliminate potential pathogens and therefore may decrease the likelihood of transmission.

Search for natural alternatives

In recent years, concern about chemicals, particularly the use of chemicals in the home, has led people to look for alternatives to commercial disinfectants. However, laboratory tests conducted by researchers at the University of North Carolina at Chapel Hill have shown that the natural products most often used as substitutes for commercial disinfectants are less effective at eliminating pathogens from environmental surfaces.

Scope of the study

The study evaluated both natural products and commercial disinfectants for their efficacy against potential human pathogens. Three hospital disinfectants (Vesphene IIse, TBQ and ethanol), four household disinfectants (Clorox Bleach, Lysol Disinfectant Spray, Lysol Antibacterial Kitchen Cleaner and Mr. Clean Ultra) and two natural products (baking soda and vinegar) were tested.

All products were evaluated against the test organisms Staphylococcus aureus, Salmonella choleraesuis, E. coli O157:H7 and Pseudomonas aeruginosa. These test organisms were exposed to products or controls for 30 seconds or five minutes.

The number of surviving organisms was compared with controls to quantify microbial activity. The effectiveness of the disinfectant was calculated by comparing the number of surviving organisms in the samples exposed to each cleaning product with the average number of organisms in samples not exposed to any of the products.

Commercial disinfectants are more effective

The data demonstrated that currently available commercial disinfectants have excellent activity against potentially pathogenic bacteria likely to contaminate home environmental surfaces. In fact, all of the hospital and household disinfectants exhibited "effective" to "excellent" antimicrobial activity and are therefore sufficiently active to be recommended for use. The two natural products, vinegar and baking soda, were much less effective than commercial disinfectants.

Antibiotic resistance and poliovirus

Prompted by recent questions about the effectiveness of antimicrobials against bacteria that have developed resistance to popular antibiotics, the cleaning agents were tested against both resistant and susceptible bacteria, specifically the vancomycin-susceptible and –resistant Enterococcus species and the methicillin-susceptible and –resistant S aureus. All commercial disinfectants completely inactivated both resistant and susceptible bacteria at both 30-second and five-minute exposures.

To gauge the upper limits of effectiveness, the disinfectants were tested on poliovirus, a representation of small, nonenveloped viruses that are the most resistant to chemical agents. Of the household products tested, only Clorox Bleach and Lysol Disinfectant demonstrated excellent activity against poliovirus.

Decreasing infection rates

This study demonstrates the efficacy of commercial disinfectants for use in the home. While some studies have shown that contaminated environmental surfaces are capable of transmitting viral pathogens, a controlled trial should be undertaken to determine if routine disinfection of home environmental surfaces will lead to decreased infection rates among household members.

In the meantime, persons who wish to use the most effective disinfectant should use commercial disinfectants instead of natural alternatives to decrease potential pathogens.

For more information on antimicrobial activity of home disinfectants and natural products, visit the Inspection Control and Hospital Epidemiology website at http://www.slackinc.com/general/iche/stor0100/1rut.htm. For information on Dr. Rutala, go to http://www.unc.edu/depts/spice/bio2.htm