Effect of Fingernail Length on Antisepsis Effect and Bacterial Flora of the Hand

Abstract

  The Guidelines for Hand Hygiene in Health-Care Settings released by the CDC in 2002 and the WHO Guidelines on Hand Hygiene in Health Care released by the WHO in 2009 consider that the use of waterless alcohol-based hand rubs is effective and that the fingernails should be less than 6.35 mm long in the clinical setting. We examined the effect of fingernail length on the bacterial flora of the hands of 17 volunteers. Comparison of long fingernails (5.4 mm) with short (2.4 mm) revealed significantly more bacteria on the fingers after hand hygiene (short: 4.3 CFU; long: 40 CFU). Although we did not find any significant difference between the numbers of bacteria under the fingernails before and after hand hygiene, bacteria were detected at more than 1.6×10³ CFU/mm² despite hand hygiene. The bacteria detected at high rates under the fingernails and on the fingers were Gram-positive cocci, including coagulase-negative staphylococci, and Gram-positive bacilli, including Bacillus spp. Moreover, methicillin-resistant Staphylococcus aureus and S. aureus remained on the fingers and under the fingernails and were difficult to remove. These findings suggest that the waterless alcohol-based hand rub method is difficult to use adequately if the fingernails are long.