Hand sanitizer alert.

Community-based epidemiologic studies have shown that hand sanitizers have beneficial effects. Hand sanitizers have been found to be effective in reducing gastrointestinal illnesses in households (Sandora et al., 2004), in curbing absentee rates in elementary schools (Hammond, Ali, Fendler, Dolan, & Donovan, 2000), and in reducing illnesses in university dormitories (White et al., 2003). An Internet search retrieved recommendations for hand hygiene from schools, daycare centers, outdoor guides, and animal shelters.

To reduce infections in health care settings, alcohol-based hand sanitizers are recommended as a component of hand hygiene (Boyce & Pittet, 2002). For alcohol-based hand sanitizers, the Food and Drug Administration (FDA) recommends a concentration of 60 percent to 95 percent ethanol or isopropanol (FDA, 1994), the concentration range of greatest germicidal efficacy While non-health-care groups also recommend alcohol-based hand sanitizers, they usually do not specify an appropriate concentration of alcohol.

Some products marketed to the public as antimicrobial hand sanitizers are not effective in reducing bacterial counts on hands. In the course of a classroom demonstration of the comparative efficacy of hospital-grade antimicrobial soap and alcohol-based sanitizers, a product with 40 percent ethanol as the active ingredient was purchased at a retail discount store. Despite a claim on the label that the product reduces "germs and harmful bacteria" by 99.9 percent, we observed an apparent increase in the concentration of bacteria in handprints impressed on agar plates after cleansing. Such an effect was not found with any of the other hand cleaners.

Subsequently, we conducted more formal handwashing trials to verify the preliminary finding. Our goal was not to test the products by using the FDA tentative final monograph standard (FDA, 1994), but to determine whether a marketed product fails as an antiseptic because of its low alcohol content. To test whether the relatively low concentration of ethanol was the source of treatment failure, we included trials with laboratory-formulated 40 percent ethanol; we also supplemented the suspect gel with ethanol to a final concentration of 62 percent. Five hand hygiene treatments were compared: tap water (four trials), 40 percent ethanol (five trials), commercial gels with active ingredients of either 40 percent or 62 percent ethanol (nine trials each), and commercial 40 percent gel supplemented to 62 percent (five trials).

At the beginning of each work day, the dominant hand of each volunteer was placed on 150-mm tryptic soy agar plates for 5 seconds; hand treatment followed. Each alcohol-based hand treatment involved wetting the hands with 1.5 mL of test product then vigorously rubbing the hands together for 15 seconds. The tap water treatment differed: Hands were held under running water and vigorously rubbed together for 15 seconds, and air drying followed. After hands were dry, they were reapplied to a fresh plate for 5 seconds. Participants were assigned to treatments randomly, but each had to complete each treatment in a week. CFU counts before and after treatment were log-transformed to normalize data and compared through paired t-tests.

Tap water, 40 percent ethanol, and 40 percent ethanol gel yielded no significant reductions in CFUs. The 40 percent gel supplemented with ethanol to a final concentration of 62 percent reduced the mean CFUs by 90 percent, a level of reduction similar to that provided by the 62 percent ethanol gel. Moreover, the 62 percent gel and the supplemented 40 percent gel reduced CFUs by >50 percent for all participants. In contrast, only one-third of participants showed >50 percent reductions with 40 percent gel, one-fifth with 40 percent ethanol, and none with tap water. Differences in pretreatment CFUs were not significant (analysis of variance: F = 1.81, df = 4, 27, p = .16). In addition to failing to decrease CFUs, use of 40 percent gels resulted in more even distribution of colonies on postwash plates. The even postwash colony distribution may be caused by dispersion of aggregates of microbes without sufficient killing.

Qualitative colony assessment suggested that 40 percent gel and 40 percent ethanol were as effective as 62 percent gel against fungi; in contrast, bacterial CFUs tended to show little change or increases. The most prevalent bacteria were staphylococci, including those with characteristics of Staphylococcus aureus.

After the experiments were conducted, a survey of six local retail chains found no substandard products. In the fall of 2005, a more extensive survey of 18 retail chains (supermarkets, drugstores, general retailers, specialty shops) uncovered a substandard product at all three stores of one deep-discount chain. The marketing profile of deep-discount chains suggests that poorer segments of the population may be more at risk of purchasing inadequate antiseptic gels. Moreover, 40 percent ethanol products may be stockpiled in homes and offices. An extensive Internet survey identified no additional substandard commercial products. The alcohol content of less common brands was not always available online, however, and several Internet sites provide recipes for a bubble gum-scented children's hand sanitizer that contains 33 percent isopropanol as the sole active ingredient. Educational efforts should emphasize that effective sanitizers must contain a sufficient alcohol concentration.

The efficacy experiments reported here reinforce what has been known for more than 50 years: 40 percent ethanol is a less effective bacterial antiseptic than 60 percent ethanol (Price, 1939). Consumers should be alerted to check the alcohol concentration in hand sanitizers, because substandard products may be marketed to the public.

(Adapted with permission from Emerging Infectious Diseases, Vol. 12, No. 3, March 2006. The original article is available from www.cdc.gov/ncidod/EID/voll2no03/05-0955.htm.)

References

Boyce, J.M., & Pittet, D. (2002). Healthcare Infection Control Practices Advisory Committee, HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. Guideline for hand hygiene in health-care settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. MMWR Recommendations and Reports, 51 (RR-16), 1-45.

Food and Drug Administration. (1994). Topical antimicrobial products for over-the-counter use: Tentative final monograph for healthcare antiseptic drug products. Federal Register, 59, 31221-31222.

Hammond, B., Ali, Y., Fendler, E., Dolan, M., Donovan, S. (2000). Effect of hand sanitizer use on elementary school absenteeism. American Journal of Infectious Control, 28, 340-346.

Price, P.B. (1939). Ethyl alcohol as a germicide. Archives of Surgery, 38, 528-542.

Sandora, T.J., Taveras, E.M., Shih, M-C, Resnick, E.A., Lee, G.M., Ross-Degnan, D., et al. (2004). Hand sanitizer reduces illness transmission in the home [Abstract 106]. In Abstracts of the 42nd annual meeting of the Infectious Disease Society of America; Boston, Massachusetts; 2004 Sept 30-Oct 3. Alexandria: Infectious Disease Society of America.

White, C., Kolble, R., Carlson, R., Lipson, N., Dolan, M., Ali, Y., et al. (2003). The effect of hand hygiene on illness rate among students in university residence halls. American Journal of Infectious Control, 31, 364-370.