Regular Hand Rubbing with Alcohol Results in a Sustained Reduction of Bacterial Numbers, and May Also Increase Carriage Rate of Gram-negative Bacteria

Background: Alcohol-based hand rubbing provides several advantages compared to hand washing with soap and water, and has become the primary method for hand hygiene in healthcare. However, the residual effects of frequent alcohol exposure on hand microflora are not well established.

Objective: To examine hand microecology of healthcare workers (HCW) before and after switching from hand washing to alcoholic hand rubbing as the primary method for hand hygiene in a tertiary care hospital.

Methods: Hand samples were collected by the glove juice technique. HCW were interrupted in their normal work activities without prior notice, at least 2 hours after starting their work shift. No extra hand hygiene was allowed before sampling. The samples were examined for total numbers of colony forming units (CFU) as well as presence of Staphylococcus aureus, Enterobacteriaceae and non-fermentative Gram-negative bacteria. Sampling was done 6 months before (2004) and 2 years after (2007) a hand hygiene campaign in 2005, enforcing hand disinfection with alcohol as the primary method for hand hygiene.

Results: Both hands of 132 and 155 HCW were examined in 2004 and 2007 respectively. In 2004, 61.4 % of the subjects reported no use of alcohol-based hand rub on the day of sampling, whereas this figure dropped to 18.1 % in 2007 (p < 0.001, Pearsons Chi-square).
A significantly reduced median number of CFU was found on the hands in 2007 (900 000 CFU, CI95% [212 500 – 2 825 000]) compared to 2004 (3 563 125 CFU, CI95% [1 990 000 – 5 903 125], p < 0.001, Man Withney U).
A significant difference was also observed between HCW that had not performed alcoholic hand rubbing on the day of sampling (1 203 125 in 2007 (n= 28) vs. 3 650 000 in 2004 (N=81), p < 0.001, Man Withney U). No significant differences were found in recovery of S. aureus (20.5 % vs. 23.2 %, p = 0.668, Pearsons Chi-square) or non-fermentative Gram-negative bacteria (30.3 % vs. 36.8 %, p = 0.248, Pearsons Chi-square). However, a significant increase was observed for carriage of Enterobacteriaceae (9.1 % vs. 23.2 % p = 0.001, Pearsons Chi-square).
Conclusions: The overall median bacterial load on hands was reduced by approximately 75 % after introduction of alcohol-based hand rubbing as the primary method for hand hygiene. Since a significant reduction was observed even in personnel who had not disinfected their hands on the day of sampling, we suppose that this effect is at least partly due to a reduction of the resident hand flora as a result of hand disinfection on previous days. This may have a negative impact on resistance to temporary bacterial contamination by Enterobacteriaceae and other potentially pathogenic bacteria.