How do I clean my dermatoscope?
A question that recently came up so I thought I would look at the available evidence and guidelines. As a medical device which has skin contact, there is the potential for a dermatoscope to transfer potentially pathogenic microorganisms from one patient to another during consultations, so what is best practice?
Studies of bacteria present on a dermatoscope
Medical Devices are well known a source of nosocomial infections (an infection acquired when receiving medical care). Studies have identified a range of medical devices such as stethoscopes [1], blood pressure cuffs [2], otoscopes [3] etc., as potential source of infection. In 2001, the first study was conducted in Vienna [4] looking at dermatoscope and its potential to transmit infections. The work involved repeated random swabs of devices used in a busy hospital outpatients. The devices were used on 30-40 patients a day (mainly outpatients) and swabbed over a five-month period. The swabbing included both the head (lens) of the device and the handle. After disinfection, the device was used on patients using clingfilm as a barrier.
The results were divided into inpatient (n=20) and outpatient (n=19) profiles. Despite some minor differences, the number of colony forming units (CFU) of bacteria was similar for both patient groups – for the lens and the handle areas. The lenses tending to hold higher numbers of CFU’s than the handles - as would be expected.
After cleaning the device with isopropyl alcohol, the devices showed no CFU’s on the lenses with and a median of two CFU’s on the handles of the devices. When clingfilm was used on the devices, after removal for swabbing, no CFU’s were isolated on the heads or the lens of any device. A sub-analysis showed that clingfilm application to the device did not degrade the image quality during use.
Alcohol Gel for Dermatoscopes
In 2006, a study looked at using an alcohol gel as an immersion fluid between the dermatoscope and the patient’s skin [5]. Three devices were cleaned initially with 70% isopropyl alcohol and air dried for a minute. Subsequently, all patients underwent dermatoscopic examination with alcohol gel as the contact medium. All the 31 swabs from the device lenses showed a negative culture after 24 and 48 hours. Once again, as per the first study, there was not degradation in image quality using the alcohol gel. The authors concluded alcohol hand gel is a portable and usable medium.
A third study published in 2006 [6], reviewed the microbiology of dermatoscopes using oil as the immersion fluid. A total of 112 swabs from devices at two locations were taken. Just under a third (35%) showed no bacterial growth and 65% showed growth of non-pathogenic or skin flora bacteria. Three swabs demonstrated staphylococcus aureus. The use of isopropyl alcohol as a contact medium demonstrated in 11 swabs showed only skin flora or no growth upon culture.
The most recent study, from the UK, evaluated the lenses of 9 devices, 60 times (30 times before clinic and matched 30 times after a dermatology clinic) over 4 months. The study identified 10% of samples demonstrating the presence of pathogenic bacteria including staphylococcus aureus.
Practice Points
From the available evidence, it shows that dermatoscopes may potentially carry pathogenic bacteria, which could be transferred from patient to patient. In practice though, there are no reported cases of proven cross infection through routine use. The limited reports suggest that isopropyl alcohol should be used on the lens plates as well the handle, in between patients to reduce this risk of cross-contamination.
Manufacturers over the years have been aware of this issue and with some device adjustments have attempted to reduce the risk further. HEINE for example, on their recent device the DELTA X have introduced disposable caps which can be used on individual patients (See figure). 3GEN have a similar disposable device (they call "icecaps") for some of their devices (including the DL5 and others in their range), which can be disposed of after use. In addition, removable face plates can be autoclaved (such as on the DELTA 30 range).
In the current position with lack of detailed robust evidence, the use of 70% isopropyl alcohol as a cleaner between patients would seem advisable based on the data available. Moreover, for skin which is broken and carries a higher potential risk the use of a disposable cap or even clingfilm can reduce the risk of cross-contamination. With every device, the instructions for use will carry instructions on the necessary cleaning required between patients. These include the use of alcohol and other disinfectant wipes.
Manufacturers Advice
Reputable manufacturers will give details on recommendations for device cleaning.
Information from HEINE
Information from Dermlite 3GEN
References
1. Breathnach, A.S., D.R. Jenkins, and S.J. Pedler, Stethoscopes as possible vectors of infection by staphylococci. BMJ, 1992. 305(6868): p. 1573–4.
2. Walker, N., R. Gupta, and J. Cheesbrough, Blood pressure cuffs: friend or foe? J Hosp Infect, 2006. 63(2): p. 167–9.
3. Havaldar, R.R., et al., An Analysis of the Contaminants on Otoscopes of Otolaryngology Residents: An Observational Study. Indian J Otolaryngol Head Neck Surg, 2024. 76(4): p. 3386–3389.
4. Stauffer, F., et al., The dermatoscope: a potential source of nosocomial infection? Melanoma Res, 2001. 11(2): p. 153–6.
5. Kelly, S.C. and S.M. Purcell, Prevention of nosocomial infection during dermoscopy? Dermatol Surg, 2006. 32(4): p. 552–5.
6. Hausermann, P., A. Widmer, and P. Itin, Dermatoscope as vector for transmissible diseases - no apparent risk of nosocomial infections in outpatients. Dermatology, 2006. 212(1): p. 27–30.
