Computer keyboards and the spread of MRSA

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  • 2. Kniehl E, Becker A, Forster DH. Bed, bath and beyond: pitfalls

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    and keyboard isolates (Laboratory of Hospital

    Letters to the Editor390doi:10.1016/j.jhin.2005.08.017

    Computer keyboards and the spread of MRSA


    In UK intensive care units (ICUs), at least 16% ofpatients are colonized with methicillin-resistantStaphylococcus aureus (MRSA).1,2 The computerkeyboard and mouse represent a high contact areafor all staff, who may spread the organism withoutdirect patient contact.2,3 Responsibility for key-board cleaning is often in doubt and may beoverlooked. Prior to hospital-wide introduction ofelectronic records, we performed a study in our ICUto determine the incidence of MRSA contaminationof bedside keyboards.

    This prospective study was carried out in the 18-bedded ICU of a central London teaching hospital.Patients were screened for MRSA on admission andthen weekly. Sampling was performed with horseblood/Columbia agar contact plates of surface area23.76 cm2 (Oxoid, Basingstoke, UK). Growth wasassessed by colony type and Gram stain. MRSA wasidentified by subculture on to mannitol oxacillin saltagar. A full sensitivity profile and phage typing wereperformed to assess the similarity between patientin prompt eradication of methicillin resistant Staphylococcusaureus carrier status in health care workers. J Hosp Infect2005;59:180187.

    3. Allen KD, Anson JJ, Parsons LA, et al. Staff carriage ofmethicillin-resistant Staphylococcus aureus (EMRSA 15) andthe home environment: a case report. J Hosp Infect 1997;35:307311.

    4. Dealler S. Methicillin resistant Staphylococcus aureus infec-tions and colonisations in an intensive care unit apparentlystopped by environmental factors. J Hosp Infect 2004;58:238.

    5. Silvestri L, Petros AJ, Sarginson RE, et al. Handwashing in theintensive care unit: a big measure with modest effects. J HospInfect 2005;59:172179.

    P. Sanderson*

    26 Chalcot Road, London NW1 8LN, UKE-mail address:

    Available online 5 December 2005

    *Tel.: C44 20 7586 4442.

    Q 2005 The Hospital Infection Society. Published by Elsevier Ltd.Infection, Health Protection Agency Colindale,London, UK).

    MRSA-positive patients were not moved to a singleroom/cohort area unless they were carrying othermulti-resistant pathogens.2 Standard plus precau-tions were used2 with removal of gloves and handhygiene between patients and the environment. Thebed area was cleaned daily and after patientdischarge. All bedside data entry was performed atkeyboards with non-removable moulded covers or atone washable membrane keyboard (K-line, TiproKeyboards, Ware, UK). The keyboard covers (InpaceLtd, Minster Lovell, UK) and the membrane keyboardwere damp dusted once daily by the nurses withgeneral purpose detergent, in accordance with ICUdisinfection policy. The manufacturer of the coversrecommended a detergent or alcohol wipe daily.The selection of keyboards for sampling was randomand each was sampled daily until the patients left thebed space (for a maximum of five days). The views ofusers on acceptability of the membrane keyboardwere collected. Hand hygiene associated with key-board use was observed during 14 unobtrusive 20-minsessions.

    The ICU had 18 beds, including four single rooms.2

    There was a keyboard at each bedside and two moreat the nurses station. Between 7% and 9% of patientsadmitted to the ICU were colonized or infected withMRSA and 1012% acquired it during their stay.2

    Fifty-one samples were collected from 17 key-boards, and seven patients were MRSA positive.Eight keyboards were only sampled for one to threeconsecutive days because patients were dischargedor died. There was no significant trend in day-to-daycontamination. MRSA was detected in 11 (21%)samples from six keyboards [median 13 colony-forming units (cfu), range 151 cfu], including fourconsecutive samples taken from the membranekeyboard. The phage type of MRSA from keyboardsnear MRSA-positive patients was similar to patientisolates. However, three of the positive keyboardswere only used for MRSA-negative patients.

    Coagulase-negative staphylococci (median 43 cfu,range 1254 cfu) were found in all 51 samples taken.Bacillus spp. (4 cfu, range 119 cfu) were found in 47(92%) samples, and coliforms (3 cfu, range 116 cfu)were found in 30 (59%) samples. Methicillin-sensitiveS. aureus was detected in three samples from threekeyboards (18 cfu).

    The keyboard or mouse was touched34.5 times/h (mean) after patient/environmentalcontact (Table I). Hand hygiene was only performedprior to keyboard or mouse contact 3.2 times/h, acompliance rate of 9.3%. Only four of 22 usersquestioned (five doctors, 17 nurses) thought the

  • g 1


    Total contacts 24 60Contacts/h 5.1 12.9

    Other staff71.5

    Letters to the Editor 391membrane keyboard was easy to use. The remain-der found the keys poorly responsive, making typingslow and keeping the user away from clinical duties.The mouse pad was similarly difficult to use.

    Over one-third of the keyboards tested in ourstudy were contaminated with MRSA, regardless ofthe carriage status of the nearest patient, and handhygiene rarely accompanied keyboard contact.Overall, hand hygiene compliance in the ICU was21% which is similar to that reported in otherstudies.2 With the introduction of electronicpatient records, the risk of transmission of MRSAand other bacteria between keyboards and distantpatients is significant and may go unrecognized.

    At least nine studies have reported contaminationof keyboards and mice, including 842% with MRSA.3,4

    A study of keyboards and mice at 14 ICU beds showedthat 5.9% of 222 samples were contaminated.5 In acritical care unit in the USA, four of 11 (36%)keyboards were contaminated with MRSA.6 Currentrecommendations suggest using the same dailydisinfection process as for other bedside equipment,protecting the keyboard with a plastic cover or usingan immersible keyboard.3 Although manufacturerswebsites indicate agents that are incompatible withthe hardware, they do not address disinfection.

    Most keyboards are difficult to clean. Keyboardcovers are widely used but are not cleaned orreplaced as often as desirable, and organisms cansurvive on covers, if not cleaned, for between 1 hand 60 days.7 Although flat and impermeable, themembrane keyboard was contaminated every day itwas tested. Frequent cleaning was still needed.

    Total contacts 6Contacts/h 1.3Table I Hand contacts with keyboard and mouse durin

    Staff Patient thenkeyboard

    Other lthen k

    NursingRoutine cleaning of keyboards and mice has to bea quick, simple task. Surfaces must be impervious,smooth and resistant to common cleaning agentsincluding hypochlorite and alcohol.


    The work was supported by a grant from NHSConnecting for Health.References

    1. Hails J, Kwaku F, Wilson AP, et al. Large variation in MRSApolicies, procedures and prevalence in English intensive careunits: a questionnaire analysis. Intensive Care Med 2003;29:481483.

    2. Cepeda JA, Whitehouse T, Cooper B, et al. Isolation ofpatients in single rooms or cohorts to reduce spread of MRSAin intensive-care units: prospective two-centre study. Lancet2005;365:295304.

    3. Neely AN, Weber JM, Daviau P, et al. Computer equipmentused in patient care within a multihospital system: rec-ommendations for cleaning and disinfection. Am J InfectControl 2005;33:233237.

    4. Devine J, Cooke RP, Wright EP. Is methicillin-resistantStaphylococcus aureus (MRSA) contamination of ward-basedcomputer terminals a surrogate marker for nosocomial MRSAtransmission and handwashing compliance? J Hosp Infect2001;48:7275.

    5. Hartmann B, Benson M, Junger A, et al. Computer keyboardand mouse as a reservoir of pathogens in an intensive careunit. J Clin Monit Comput 2004;18:712.

    6. Bures S, Fishbain JT, Uyehara CF, et al. Computer keyboardsand faucet handles as reservoirs of nosocomial pathogens inthe intensive care unit. Am J Infect Control 2000;28:465471.

    7. Neely AN. A survey of gram-negative bacteria survival onhospital fabrics and plastics. J Burn Care Rehabil 2000;21:523527.

    A.P.R. Wilsona,*,S. Haymana

    P. Folana

    P.T. Ostrob

    A. Birkettb

    S. Batsoncc

    4 sessions of 20-min duration

    l areaoard

    Patient then mouse Other local areathen mouse

    35 117.5 2.4

    0 30.6M. SingerG. Bellinganc

    aDepartment of Clinical MicrobiologyUniversity College London Hospitals, London, UK

    bDepartment of Medical Physicsand Bioengineering,

    University College London Hospitals, LondoncBloomsbury Institute of Intensive Care Medicine,

    University College London and Intensive Care Unit,UCL Hospitals, London, UK

    E-mail address:

  • Available online 5 December 2005

    *Corresponding author. Fax: C44 207 636 6482.

    Q 2005 The Hospital Infection Society. Published by Elsevier Ltd.All rights reserved.


    in English hospitals


    I read with interest the paper by Coello et al.1

    highlighting the importance of measuring theimpact of surgical site infection (SSI) for definedcategories of wounds rather than for all SSIs and allsurgical procedures. We made a similar point in1992 when we looked at the cost of woundinfections in a Scottish hospital in 3482 generalsurgery and vascular patients.2 We found that theaverage excess cost per infected patient varied

    E-mail address:

    doi:10.1016/j.jhin.2005.09.010Thyroid 89

    Table II Ranking of total excess costs for eachoperative category

    Operative category Total excess costs forwound infections

    Vascular 73 629Groin hernia 25 350Varicose veins 18 944Malignant breast 14 980Cholecystectomy 9488Scrotal 3108Benign breast 2652Thyroid 1068

    Letters to the Editor392from 89 for a thyroidectomy wound infectionto 909 for a vascular surgery wound infection(Table I). To assess the overall impact of eachcategory, the cost per infected patient had to bemultiplied by the wound infection rate for that

    Table I Ranking of excess costs per infected patient

    Operative category Average excess costper infected patient

    Vascular 909Cholecystectomy 593Malignant breast 535Groin hernia 325Scrotal 148Varicose veins 128Benign breast 102Available online 5 December 2005

    *Tel.: C44 1382660111.

    Q 2005 The Hospital Infection Society. Published by Elsevier Ltd.All rights reserved.operation and the total number of patients under-going the procedure. When this was done, theranking of some of the procedures changedbetween Tables I and II. It is important toappreciate these factors when assessing thefinancial burdens of SSIs.


    1. Coello R, Charlett A, Wilson J, et al. Adverse impact ofsurgical site infections in English hospitals. J Hosp Infect2005;60:93103.

    2. Lynch W, Byrne DJ, Malek M, et al. Costing woundinfection in a Scottish hospital. Pharmacoeconomics 1992;2:163170.

    D. Byrne*Ninewells Hospital, Dundee, Tayside, UKAdverse impact of surgical site infections

    Letters to the Editor


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