Reproducibility and workability of the European test standard EN 12791 regarding the effectiveness of surgical hand antiseptics: a randomized, multicenter trial.
OBJECTIVE
To evaluate the reproducibility and workability of the in vivo test model of the European test standard EN 12791 regarding the effectiveness of surgical hand antiseptics and, as a secondary objective, to evaluate the power of the model to discriminate between the effectiveness of various formulations of surgical hand antiseptics.


METHODS
Prospective, randomized, multicenter study with a Latin square design.


METHODS
Five laboratories at 2 universities, 2 disinfectant manufacturers, and 1 private testing institution.


METHODS
Twenty healthy adults in each laboratory.


METHODS
Surgical hand antisepsis was performed by scrubbing with chlorhexidine gluconate 4% detergent (CHG) or by rubbing the hands with propan-2-OL (70% by volume; Iso 70) or ethanol 85% (E 85); rubbing the hands and forearms for 3 minutes with propan-1-OL (N 60) was used as the reference disinfection procedure. We deliberately chose to use these antiseptics at the given concentrations because they were intended to cover the range of typical antiseptics submitted for approval according to EN 12791.


METHODS
In once-weekly tests, the immediate effects of the 4 antiseptics were established according to the method laid down in EN 12791 by assessing the release of skin flora from the fingertips as viable bacteria counts per milliliter of sampling fluids before treatment and viable bacteria counts immediately after treatment, separately for both hands, such that after 4 weeks each volunteer had used every formulation once.


RESULTS
The mean log reduction factor (RF) for the release of bacterial skin flora (the log RF was calculated as the log count before treatment minus the log count after treatment) and corresponding standard deviations for the 4 hand antisepsis formulations were as follows: for CHG, 1.1+/-0.3 colony-forming units (cfu) per milliliter of sampled fluid; for Iso 70, 1.7+/-0.3 cfu/mL; for E 85, 2.1+/-0.3 cfu/mL; and for N 60, 2.4+/-0.4 cfu/mL. The differences between these values proved significant (P<.001) by analysis of variance and in Tukey's "honestly significantly different" (HSD) post hoc test. Although, with regard to their immediate antibacterial activity, the same ranking of these antiseptics was found at all laboratories, the levels of efficacy were significantly different across laboratories (P<.001); no statistical difference was found between left and right hands (P>.01). Relating the log RF values of the other 3 formulations to those of the reference formulation (N 60) abolished differences between laboratories (P=.16); in addition, the interclass correlation coefficient decreased from 9.1% to 4.5%. With 20 volunteers, a minimum difference of 0.47 log between the mean log RFs of the reference formulation and an inferior test formulation will be detected as significant at an alpha of .05 (1-sided) and a 1- beta value of .8.


CONCLUSIONS
The test method described in EN 12791 yielded the same conclusion on the effectiveness of the tested formulations in every laboratory and proved, therefore, reproducible and workable.
Rotter
Manfred
M
Institute of Hygiene and Medical Microbiology, Medical University, Vienna, Austria. manfred.rotter@meduniwien.ac.at
Kundi
Michael
M
Suchomel
Miranda
M
Harke
Hans-Peter
HP
Kramer
Axel
A
Ostermeyer
Christiane
C
Rudolph
Peter
P
Sonntag
Hans-Gunther
HG
Werner
Heinz-Peter
HP
D019840:2-Propanol / Q000494:pharmacology*; D000328:Adult; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D006235:Hand Disinfection / Q000592:standards*; D006801:Humans; D015203:Reproducibility of Results; D016896:Treatment Outcome
D000891:Anti-Infective Agents, Local; D000431:Ethanol; C010882:chlorhexidine gluconate; D019840:2-Propanol; D002710:Chlorhexidine