Efficacy of hand hygiene agents at short application times

How effective are hand antiseptics for the postcontamination treatment of hands when used as recommended?

BACKGROUND

Alcohol-based hand antiseptics are often tested using 3 or 5 mL per application, but smaller volumes are likely to be applied in clinical practice. For that reason, we investigated the efficacy of 2 different volumes of 4 marketed hand rubs when applied to contaminated hands.

METHODS

Hands of 16 volunteers were contaminated with Serratia marcescens. Hand rub A (85% ethanol), hand rub B (60% ethanol), hand rub C (62% ethanol), and hand rub D (61% ethanol) were applied as blinded formulations, each in single applications of 2.4 or 3.6 mL. Hibiclens (4% chlorhexidine gluconate) served as the reference treatment. Each hand rub was rubbed into the hands until dry. Preintervention and postintervention bacterial populations were obtained by the glove juice method. Neutralization of residual activity was validated.

RESULTS

A 2.4-mL aliquot of a hand rub product was sufficient to cover both hands in 96.9% of the subjects. Applied in that volume, hand rubs produced a log(10)-reduction in bacterial populations of 2.79 for hand rub A, 2.26 for hand rub C, 1.96 for hand rub D, and 1.90 for hand rub B. Application of 3.6 mL was significantly more effective for hand rubs B, C, and D. The reference treatment reduced test bacteria by 2.39 log(10). Analysis of variance revealed that both the type of hand rub and the applied volume had a highly significant influence on the mean log(10) reduction on artificially contaminated hands (P < .001).

CONCLUSIONS

Hand rubs applied in amounts sufficient to cover both hands may not reduce the bacterial density by even 2 log(10) steps. Based on our findings, the general trend toward alcohol-based hand rubs should not overlook evidence of significant differences in efficacy that appear to be related primarily to a product's overall concentration of alcohol.

Suitability of vaccinia virus and bovine viral diarrhea virus (BVDV) for determining activities of three commonly-used alcohol-based hand rubs against enveloped viruses

BACKGROUND

A procedure for including activity against enveloped viruses in the post-contamination treatment of hands has been recommended, but so far no European standard is available to implement it. In 2004, the German Robert Koch-Institute (RKI) and the German Association for the Control of Virus Disease (DVV) suggested that vaccinia virus and bovine viral diarrhea virus (BVDV) should be used as test viruses in a quantitative suspension test to determine the activity of a disinfectant against all enveloped viruses.

METHODS

We have studied the activities of three commonly-used alcohol-based hand rubs (hand rub A, based on 45% propan-2-ol, 30% propan-1-ol and 0.2% mecetronium etilsulfate; hand rub B, based on 80% ethanol; hand rub C, based on 95% ethanol) against vaccinia virus and BVDV, and in addition against four other clinically relevant enveloped viruses: herpes simplex virus (HSV) types 1 and 2, and human and avian influenza A virus. The hand rubs were challenged with different organic loads at exposure time of 15, 30 and 60 s. According to the guidelines of both BGA/RKI and DVV, and EN 14476:2005, the reduction of infectivity of each test virus was measured on appropriate cell lines using a quantitative suspension test.

RESULTS

All three alcohol-based hand rubs reduced the infectivity of vaccinia virus and BVDV by > or = 4 log10-steps within 15 s, irrespective of the type of organic load. Similar reductions of infectivity were seen against the other four enveloped viruses within 15 s in the presence of different types of organic load.

CONCLUSION

Commonly used alcohol-based hand rubs with a total alcohol concentration > or = 75% can be assumed to be active against clinically relevant enveloped viruses if they effectively reduce the infectivities of vaccinia virus and BVDV in a quantitative suspension test.