CHAPEL HILL - Tests of a variety of commercial household disinfectants show the products to be highly effective in killing disease-causing organisms, according to University of North Carolina at Chapel Hill researchers.
Natural products, which might be more environmentally friendly, however, were less successful in killing the hazardous organisms and should not be relied on for that purpose.
Whether routinely disinfecting contaminated home surfaces in kitchens and bathrooms reduces common communicable illnesses among family members remains an open question, the UNC-CH School of Medicine researchers say.
"We tested the hospital disinfectants TBQ, Vesphene and ethanol and the household disinfectants Clorox, ethanol, Mr. Clean Ultra and Lysol Disinfectant Spray and Lysol Antibacterial Kitchen Cleaner," said Dr. William A. Rutala, professor of medicine. "The good news was that they were all very good, eliminating 99.9 percent or more of microbes. The bad news was that such natural products as vinegar and baking soda didn't work nearly as well."
A report on the study appears in the January issue of the journal Infection Control and Hospital Epidemiology, which has just appeared. Besides Rutala, authors are Dr. Mark D. Sobsey, professor of environmental sciences and engineering at the UNC-CH School of Public Health; Dr. David J. Weber, professor of medicine; research associate Susan L. Barbee and student Newman C. Aguiar.
The scientists tested the effect of selected disinfectants against numerous disease-causing microbes after 30-second and after five-minute exposures. Organisms included Staphylococcus aureus, Salmonella choleraesuis, Escherichia coli 0157:H7, Pseudomonas aeruginosa, poliovirus, and vancomycin-susceptible and -resistant Enterococcus species. They then cultured the microbes to see how many remained.
While the commercial products killed almost all germs, in some cases the vinegar and baking soda eliminated 90 percent or fewer, the experiments showed. Among household cleaners, only Clorox and Lysol disinfectant spray demonstrated excellent activity against poliovirus, eliminating more than 99.9 percent of the virus.
Threats from poliovirus have been eliminated almost entirely in the United States, but Rutala and his colleagues tested the virus anyway since it is harder to kill than other disease-causing organisms. As a result, it is a good indicator of successful disinfection.
UNC-CH researchers conducted the independent study because effectiveness claims by manufacturers may be exaggerated, and many products are not tested against important viruses and bacteria, he said. Growing concerns about emerging infectious diseases and antibiotic-resistant microbes also sparked their interest.
"We now know that kitchen and bathroom surfaces in most homes show high levels of contamination that can lead to disease and that disinfectants can eliminate most of that contamination," Rutala said. "What we don't know yet is whether disinfecting drains, taps, handles and toilet seats would actually decrease infection rates among family members. It may be that more direct contact in families such as touching, kissing, sneezing and sharing food or eating utensils plays a much bigger role in spreading infections."
More than 30 million food-borne infections have been estimated to occur each year, resulting in more than 9,000 deaths, the researcher said. Scientists also estimate that more than 2 million hospital-acquired infections cause more than 19,000 deaths and contribute to another 58,000 annually. Contamination in day-care centers frequently leads to diarrhea and other diseases but only rarely to fatalities in the United States.
The N.C. Statewide Program for Infection Control and Epidemiology supported the study.
Note: Rutala can be reached at (919) 966-1635 or via e-mail at email@example.com.
Contact: David Williamson, 962-8596.