Small volumes of n-propanol (60%) applied for 3 minutes may be ineffective for surgical hand disinfection

BACKGROUND: There is a trend in some countries to recommend the use of surgical hand disinfectants at volumes as low as 4 ml per application. AIM: To determine whether the volume applied and hand size influence the efficacy of surgical hand disinfection. METHODS: Thirteen experiments, according to EN 12791, resulting in 269 datasets from 75 subjects were analyzed. Hands were first washed for one minute with soap. The pre-values were obtained by rubbing the finger tips in tryptic soy broth for one minute. Each subject treated his/her hands with n-propanol (60%, v/v), with as many portions as necessary to keep the hands wet for three minutes (6–12 ml). Bacterial post-values were taken from one hand (immediate effect); the other hand was gloved for three hours (sizes 7–9). The second post-value was taken when the glove was removed (3 h effect). RESULTS: The mean immediate log(10) reduction of CFU was 2.56 ± 1.12. The glove size had no significant effect on the efficacy of disinfection (p = 0.182; ANOVA). However, a volume of 6 ml was significantly less effective than 9 ml for glove sizes of 7.5–8 (p < 0.05; Tukey post hoc analysis). The mean log(10) reduction after 3 h was 2.12 ± 1.24. A volume of 6 ml was again significantly less effective than 12 ml for glove size 7 and than 9 ml for glove sizes 7.5–8 (p < 0.05). CONCLUSIONS: The application of small volumes of surgical hand disinfectant when using the EN 12791 reference procedure is likely to yield poor efficacy results, regardless of hand size.