Human Hands and Fingernails

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Fingernails affected by onychomycosis

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Current Research

‘Super’ bacteria live on sheets, fingernails: study [1]

On June 6, 2005, U.S. researchers reported that MRSA (methicillin-resistant Staphylococcus aureus ) is commonly found on computer keyboard covers and under fingernails which causes rashes and infections. MRSA has resistance to almost everything besides an antibiotic called vancomycin. Vancomycin binds the end of D-ala D-ala which blocks transpeptidation of bacteria to inhibit its growth. Although Staphylococcus aureus is usually harmless and found on skin, it can sometimes cause necrotizing fasciitis or “flesh-eating” disease in hospitals. A study at Northwestern Memorial Hospital in Chicago shows that computer keyboard can contaminate the fingers of a doctor or a nurse, and then further transfer the bacteria to patients thus causing deadly infections.

Onychomycosis due to artificial nails [2]

Although the use of artificial nails is a popular trend nowadays, several bacterial and fungal infections such as Onychomycosis have been found in patients who use artificial nails. Onychomycosis is a fungal infection of the nail which causes 50% of all nail diseases and affects 18% of the general population. Due to the use of artificial nails, Onychomycosis is found to be very common in nail changes. The researchers performed KOH examination and fungal culture to detect the fungal infection from the distal part of the nail and from the proximal nail fold. The results show that both KOH and culture were significantly better in the samples from the distal part of the nail compared to the samples from the proximal nail fold. The study demonstrates that the use of artificial nails can lead to increasing chance of transmitting bacteria. People should avoid using artificial nails especially for health care personnel and food industry workers.

Ultraviolet C inactivation of dermatophytes: implications for treatment of Onychomycosis. [3]

In this study, researchers were trying to find an alternative treatment besides antifungals to treat Onychomycosis. The major purpose of the study is to test whether ultraviolet C is able to sterilize a novel ex vivo model of nail infection. Infected human toenail clippings were irradiated with ultraviolet C (254 mm) at a radiant exposure of 36-864 J cm(-2). The results show that ultraviolet C successfully inactivated Trichophyton rubrum and its resistance to ultraviolet C did not increase after five cycles of inactivation in vitro. The radiant exposure might vary depends on the thickness of the vivo culture. Ultraviolet C irradiation might become an alternative treatment for Onychomycosis in the future after researchers find a way to prevent mutations caused by ultraviolet irradiation.

Fast and sensitive detection of Trichophyton rubrum DNA from the nail samples of patients with Onychomycosis by a double-round polymerase chain reaction-based assay. [4]

Trichophyton rubrum is one of the pathogens that can be isolated from patients who have Onychomycosis. Using traditional culture-based method to isolate Trichophyton rubrum is a time-consuming process and usually leads to false detection. The study shows it is possible to detect Trichophyton rubrum in fingernail samples using double-round polymerase chain reaction-based assay which is used for DNA detection. The isolated Trichophyton rubrum DNA was amplified using actin gene and internal transcribed spacer 1 in double-round polymerase chain reaction (PCR). The combined detections shows positive results in patients undergo fungal infections. The results suggest PCR is a fast, sensitive and accurate method for fungal detection.

Yale University Experiment [5]

Dr. David Katz of Yale University, the United States, did an experiment with his students to test out the bacteria grow under fingernail. They took swab from under fingernails from different students and let the bacteria to grow. Dr. Katz also took another swab after they wash their hands. After 3 days of growing time, they found out short painted nails have least of bacteria growth. On the other hand, long unpainted nails have most of growth. The reason is because of shorter fingernails are easier to clean. The nail polish is constituted of phthalates, toluene, and formaldehyde which are toxic thus minimizing bacterial growth. The technique of hand washing is also important for limiting bacteria under fingernail. Washing hand properly can kill most of the bacteria under fingernails.


1. 'Super' bacteria live on sheets, fingernails: study

2. Onychomycosis due to artificial nails. Shemer A, Trau H, Davidovici B, Grunwald MH, Amichai B. J Eur Acad Dermatol Venereol. 2008 Mar 18

3. Ultraviolet C inactivation of dermatophytes: implications for treatment of Onychomycosis. Dai T, Tegos GP, Rolz-Cruz G, Cumbie WE, Hamblin MR. Br J Dermatol. 2008 Jun;158(6):1239-46. Epub 2008 Apr 10.

4. Fast and sensitive detection of Trichophyton rubrum DNA from the nail samples of patients with Onychomycosis by a double-round polymerase chain reaction-based assay. Gupta AK, Zaman M, Singh J. Br J Dermatol. 2007 Oct;157(4):698-703. Epub 2007 Aug 21.

5. Yale Experiment

Edited by [Chao-Lin Chen], students of Rachel Larsen