Fingernail Length and Microbes
Relationship Between Nail Length and Microbial Yield
Several outbreaks of infection in healthcare institutions have been associated with the ineffective hand hygiene practices of healthcare workers. Some of the risk factors identified with infection have included poor hand cleansing technique, as well as wearing chipped and worn fingernail polish, artificial fingernails, and even long natural fingernails.
Hospital infection control teams struggle to reduce the risk of infection to patients in intensive care and other medical units who are especially susceptible to infection. Surgical wounds, endotracheal tubes, catheters and IV lines provide direct access into the body for bacteria to enter. The hands of healthcare workers are excellent vectors on which to pass infection, and hand-hygiene awareness campaigns are ongoing in healthcare institutions because of this. However, the ability to rid the fingernails of potentially harmful bacteria through routine handwashing has been a topic of study.
Two infection outbreaks in neonatal intensive care units, one in 2001 in Oklahoma,(1) involving Pseudomonas aeruginosa bloodstream infection and endotracheal tube colonization, and another in New York in 2004,(2) involving extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae brought attention to the risk of infection associated with artificial fingernails and long natural fingernails. Sixteen of the 46 infants infected with Pseudomonas aeruginosa died as a result of the Oklahoma outbreak. Preventive recommendations resulting from investigations into these outbreaks included policies to prohibit the wearing of artificial fingernails by healthcare workers who have direct patient contact. The investigators in both outbreaks of Klebsiella pneumoniae also recommended that short, well-groomed natural fingernails be mandatory for direct care-givers.
In a separate study conducted by Dr. Shelly McNeil at Ann Arbor Healthcare System in Virginia and the University of Michigan, the relationship between fingernail length and microbial colonization of the fingernails of healthcare workers was investigated.(3) Fingernail lengths of the 5 fingers on the dominant hand were measured from underneath the nail from where it meets the skin, and the mean length calculated. The surface of the nails were swabbed and debris collected from under the fingernails.
Growth from the cultures was identified and quantified to correlate the length of fingernails with microbial yield. Pathogens were isolated more often from the nails of healthcare workers with long fingernails (> 3mm) than short fingernails (< 3 mm). Based on the findings, the investigators recommended infection control policies to restrict fingernail length of healthcare workers to less than or equal to 3 mm(about the length of the graphite tip of a pencil). Dr. McNeil is currently involved in a second larger study of healthcare workers through Dalhousie University in Halifax, Nova Scotia, to further correlate fingernail length, microbial yield, and the effectiveness of hand cleansing techniques.
Sources:
(1) Gupta A, P Della-Latta, B Todd, P San Gabriel, J Haas, F Wu, D Rubenstein, and L Saiman. Outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit linked to artificial nails. Infect Control Hosp Epidemiol. 2004, 25(3):210-5.
(2) Crutcher JM, VH San Joanquin, LV Sewell, LC Hutwagner, LA Carson, DA Robison, LM Smithee, and WR Jarvis. A prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: did staff fingernails play a role in disease transmission? Infect Control Hosp Epidemiol. 2000, 21(2):77-9.
(3) SA McNeil, A Phelps, A Barnes, and CA Kauffman. The Effect of Fingernail Length on Microbial Colonization of the Hands of Health Care Workers (HCW). 39th Annual Meeting of the Infectious Diseases Society of America (IDSA), 2001.
