Evaluation of antibacterial effect of hand hygiene gel on different concentrations of bacteria

For the prevention of nosocomial infections, hand hygiene is very important. One of the best ways to destroy microorganisms is using alcohol-based hand hygiene gel. The purpose of this study is was to evaluate the effectiveness of hand hygiene gel when encountering different concentrations of bacteria.
For this study we chose a common hand hygiene gel used in our hospital. Initially, serial dilutions of Staphylococcus aureus were prepared using 1 McFarland turbidity standard suspension in eight tubes. Then different concentrations of bacteria were encountered with the hand hygiene gel. After four different encounter duration a sample was obtained and cultured on blood agar medium and bacterial growth was examined.
Hand hygiene gel was not effective when encountered with the highest concentration of bacteria in all four time-tested, and the entire surfaces of the plates were coated with bacteria, and with decreasing concentrations of bacteria and increasing the encounter duration, the number of bacteria reduced.
This study showed that basic hand hygiene gel was only effective when the number of bacteria was lower than CFU per milliliter and the exposure time was at least 40 seconds. Accordingly, as the average numbers of bacteria on hands are far less than this threshold the routine use of hand hygiene gel is recommended, and in case of high pollution hands should be washed first.