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STUDIES in human hospitals have shown that objects such as door handles and computer keyboards can act as sources of contamination with bacteria such as meticillin-resistant Staphylococcus aureus (MRSA) and Campylobacter (Bures and others 2000, Kassem and others 2007). The aim of this study was to investigate whether bacteria were present on keyboards used in consulting rooms in veterinary practices in the UK, and to identify whether these keyboards could be a source of pathogenic bacteria that could affect animals or human beings.
Fifty-six small animal and mixed veterinary practices in Scotland were randomly selected from the RCVS directory of practices. Twenty practices agreed to take part and were visited in person by the researcher (MAF).
Only computer keyboards used within consulting rooms were included in the study. All the practices were visited at the end of a consulting period, and the keyboard was swabbed using a method described by Bures and others (2000). Cotton-tipped swabs soaked in sterile PBS were used to swab the surface of the keys and computer mouse. One swab was taken from each keyboard. The swabs were then placed in transport medium and sent to the laboratory at Glasgow University Veterinary School for culture and identification. A questionnaire was used at each practice to gather information about the methods used to clean the computer keyboards and the frequency with which they were cleaned.
In total, 41 keyboards were sampled at the 20 practices: one keyboard was sampled at nine practices, two at six practices, three at four practices and four at two practices. Bacteria were cultured from 38 swabs and fungi from one swab; the other two swabs were negative on culture. Thirty-one species of bacteria were isolated (Table 1). The most commonly isolated bacteria were Acinetobacter lwoffii and Pseudomonas stutzeri. The most commonly detected pathogenic bacteria were Pseudomonas and Enterococcus species. S aureus was not isolated from any of the keyboards sampled.
The cleaning methods varied between practices; keyboards at eight of the 20 practices were cleaned either on an occasional basis or not at all (Table 2). Of the 41 keyboards sampled, only three had a cover; two of these covers were removable for cleaning and the other was permanently adhered to the keyboard. A variety of bacteria, including A lwoffii and Enterococcus faecium, were detected on the adhered cover. Bacterial culture was negative for one of the covers that could be removed for cleaning; only single colonies of Staphylococcus epidermidis and Aerococcus viridans were cultured from the other.
The results of this study demonstrated that a high number of keyboards (38 of 41, 92·7 per cent) were positive for the presence of bacteria, both pathogenic and non-pathogenic. This is comparable with reported culture rates of between 85·1 per cent (Hartmann and others 2004) and 95 per cent (Schultz and others 2003) from keyboards in human hospitals.
Fewer species of pathogenic bacteria were isolated from keyboards in these veterinary practices than in human hospitals. No Salmonella, Campylobacter or MRSA were detected from any of the keyboards sampled, whereas these organisms have predominated in studies carried out in human hospitals (Bures and others 2000, Kassem and others 2007). Most of the bacteria isolated were commensals from dog or cat skin. Although these species are usually non-pathogenic, they can cause disease in immunocompromised human and veterinary patients (Brandenburg and others 1996, Brazzola and others 2000, Fernandez-Ayala and others 2001).
The practices included in this study did not use consistent methods for cleaning the computer keyboards, and some were cleaned rarely or not at all. It is interesting to note that while practices will routinely use disinfectants to clean cages and tables, some opted for the use of household cleaning agents to clean the keyboard (Table 3).
In conclusion, this study has demonstrated that computer keyboards are a potential source of transmission of bacteria within veterinary practices, although the numbers of different species of pathogenic bacteria in veterinary practices appear to be lower than those identified in human hospitals.
The authors thank Bayer for funding this research, and Professor David Taylor of Glasgow University Veterinary School for advice and guidance regarding the microbiological findings.
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