Download Multi-drug Resistant Organisms on Computers in Dental Offices

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Multidrug-resistant organisms (MDROs), which have been a concern in
hospitals and chronic care facilities for years,1-4 are now found in the general
community—outside of medical health care environments.5-7 Preventing
crosscontamination and identifying the source of these pathogens are key in
reducing exposure to and transmission of these organisms. MDROs may
reside in sites within the dental office that are not normally considered for
decontamination. Recognizing potential sources of contamination, following
basic hygiene precautions, and using barrier procedures can reduce the risk
of MDRO transmission to dental patients and dental health care providers.
The recent outbreak of the H1N1 flu (swine flu) highlights the necessity of
maintaining effective infection control protocols. For recommendations
specific to the H1N1 flu, visit the Organization for Safety and Asepsis
Procedures' (OSAP) website at www.osap.org.
The Concern
Educational Objectives
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MDROs, including methicillin-resistant Staphylococcus aureus (MRSA),
potential
vancomycin-resistant enterococci (VRE), and certain gram-negative bacilli
cross-contam inati w ithi
(GNB), can be found in the dental practice. Although MDROs most frequently
dentaloffice.
appear as acquired infections in hospitals and acute care facilities,1 they
have become increasingly reported in the community5,9 where they can
acquiri
transm itti
trigger serious health problems, and may even cause death.5,9,17,18 A
pathogens.
nosocomial infection, which is secondary to a patient's original condition,
develops when a patient receives treatment in a clinic or hospital setting.1-5
Nosocomial infections play a significant role in the growth of health care costs and morbidity in health care
facilities. Many organisms found in nosocomial infections are MDROs.
MRSA is a resistant and virulent organism.2,3 This gram-positive bacterium is common among hospitalized
patients who are immune suppressed, as well as the elderly and the very young. Patients who undergo surgery
and those with indwelling devices, such as intravenous lines, drains, catheters, or nasal tracheal tubes, are
especially at risk. MRSA frequently lives on the skin and in the nasal passages of patients and health care
workers without causing health problems. These bacteria can be spread from person to person through casual
contact or through contaminated objects or surfaces.
In 2005 an estimated 94,360 cases of MRSA infection occurred in the United States. More than 18,000 deaths
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are caused annually by MRSA infections.9 MRSA can be found in healthy people living in the general
community. These bacteria can cause infections in nonhospitalized, healthy individuals who have cuts or wounds
and have close contact with others.6-9 Recently, several deaths have been reported from community- acquired
MRSA infections.9,17,18
Dental patients may carry a MDRO, which could conceivably be transmitted to dental office staff or other
patients. The potential for transfer of MDROs to dental office staff from a patient, to a patient from a dental health
care provider, or from the dental practice environment to patient or health care provider has not yet been
established. But as much as 25% of health care workers may carry MRSA in their nasal passages.1,7,8
Sources of Contamination in a Dental Office
Most sterilization and cross-contamination procedures in dental practices are focused on eliminating the transfer
of microbes from patient to patient or between office staff and patient. However, contamination can occur from
inanimate surfaces to patient or practitioner. Thus, the careful sterilization of instruments and trays; cleaning and
disinfection of dental chairs and cabinets; and placing disposable covers over light handles, radiograph controls,
handpieces, three-way syringes, and head rests are important contamination control practices in dental
settings.10
Often overlooked as pathogen reservoirs are computer keyboards, computer mouse
devices, telephones, pens, patient charts, ultrasonic controls, light cure wands, front
desk counter tops, stethoscopes, blood pressure cuffs, door knobs, and wash basins
in restrooms.12-16 Since computers are used by most dental practices in the United
States, office computers and their ancillary components need to be examined as
possible contaminants in the fight against MDROs. The computer keyboard/ mouse is
found in the operatory, at the receptionist's desk, the business office, the dentist's
desk, and occasionally, the sterilization station and laboratory. The same computer
station may be used by several individuals during the day—opening up the possibility
for crosscontamination. To investigate this possibility further, we conducted a small
research study in 2008 at Skagit Valley Hospital in Mount Vernon, Wash, and 12 dental practices within the local
community. The micro-assays were done in Seattle at a commercial laboratory.
The Study
The purpose of this study was to illustrate that there are contaminated surfaces within the dental office that
clinicians may not consider as reservoirs of MDROs, that these surfaces can be somewhat effectively cleansed,
and that washing hands frequently is a recommended method of avoiding the spread and acquisition of these
organisms.
Although there are many other surfaces within a dental office that may have the same potential for crosscontamination, this study examined only the computer keyboard/ mouse. To evaluate the initial level of
contamination of keyboards/mouse devices, 88 computer keyboards/mouse devices, which had never been
cleansed or disinfected, were sampled for microbes present. Then three groups were assembled. The first
consisted of 13 conventional keyboards/mouse devices that were not disinfected; the second contained 14
conventional keyboards/ mouse devices that were disinfected/ cleansed three times a day with a disinfectant;
and the third encompassed 12 sealed keyboard/mouse devices that were disinfected/ cleansed three times a
day. All groups were evaluated for contamination over a period of 4 months. These computer keyboard/ mouse
devices were located in various locations in dental offices— reception, operatories, and the dentist's desk. The
phones, desk, and pens at the work stations in the second and third groups were disinfected three times a day
as well.
A disinfectant wipe consisting of 12% n-alkyl (60% C14, 30% C16, 5% C12, 5% C18) dimethyl benzyl ammonium
chloride; n-alkyl (68% C12, 32% C14) dimethyl ethyl benzyl ammonium chloride; and 63.25% isopropyl alcohol
was used for 2 minutes and refreshed if it became dry. This commercial disinfectant method was selected as
representative of one typically used in dental practices. In-service training was provided for all staff who might
come in contact with these keyboards/mouse sites.
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The sealed keyboard/mouse was flat and impervious to fluids. A flashing light reminded the user to disinfect the
keyboard and mouse at a preset interval.
To determine the level of microbial contamination, a single sterile swab moistened with Trypticase soy broth
(TSB) was wiped over the entire keyboard or mouse surface. The swab was placed in 2 ml of TSB and
immediately transported to the laboratory. Samples were taken at random, unannounced intervals over 3
months.
After the swab was vortexed for 1 minute 100 microliters of the specimen were
plated onto Trypticase soy agar with 5% sheep blood using the spread plate
technique. The specimen was incubated at 37° C for 48 hours. Isolates were
identified on the basis of Gram stain, colony morphology, detection of hemolysis
on sheep blood agar, and colony pigmentation, as well as results of the tube
coagulase test (for Staphylococcus species), detection of NaCL, results of the
bile-esculin test (for Enterococcus species), and detection of conidia by
microscopy (for Aspergillus species). Susceptibility testing was performed on
Stapyhlococcus aureus and enterococcal isolates by using antibiotic containing
agars (6 microliter for oxacillin and 6 microliter for vancomycin).
Results
These data are reported as a percent of total keyboards/mouse sites examined
with the specific organism detected. Of the 88 conventional keyboards/mouse
devices not disinfected or cleansed in the initial evaluation, 25% harbored
lactose-fermenting gram-negative rods, 88.6% coagulase-negative
Staphylococcus species, 23% Bacillis species, 2% Enterococcus species, 2%
gram-negative rods, and 9% Staphylococcus aureus (see Figure 1).
In the 4-month evaluation period, 26 conventional keyboards/mouse devices not
cleansed or disinfected were evaluated as a control. This group harbored 73% coagulase-negative
Staphylococcus species,15% lactose fermenting gram-negative rods, 4% diptheroids, and 8% Staphylococcus
aureus (Figure 2). These data are similar to findings in the not cleansed/ disinfected group in the previous
paragraph.
Ten sealed keyboards/mouse pairs wiped three times a day with disinfectant harbored 5% coagulase-negative
Staphylococcus species, 10% Bacillus species, and 10% lactose fermenting gram-negative rods. Three sealed
disinfected/ cleansed keyboard/mouse devices had no detectable organisms (Figure 3).
Of the 12 conventional keyboards/ mouse pairs that were disinfected/cleansed, 25% harbored coagulasenegative Staphylococcus species; and 75% had no detectable organisms (Figure 4). Both of these later groups
had fewer detectable organisms than either of the keyboard/ mouse groups that were not cleansed/ disinfected.
Discussion
1. Observations21,22 in the medical literature that clinic and hospital computer
keyboards harbor bacteria related to MDROs, such as Staphylococcus aureus,
enterococci, and Gram-negative bacilli, were also true for the dental office.
2. Both conventional and sealed keyboard/ mouse devices experienced a
reduction in detectable organisms when disinfected three times a day. Although disinfected keyboard/ mouse
pairs had reduced levels, the potential MDROs enterococci and Staphylococcus aureus were still found.
3. Using disinfectant wipes on a conventional computer keyboard did no apparent damage to the keyboard.
4. With respect to disinfection/cleansing, a sealed keyboard/mouse may offer some advantages over a
conventional keyboard/ mouse, including the ease of wiping, compliance, and the light reminding the operator to
disinfect at regular intervals.
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5. The data suggest cleansing the work area with disinfectant wipes three times a day (keyboard, mouse,
desktop, pens, and telephone) can reduce detectable organisms.
Study Weaknesses
This trial did not evaluate the survival time of pathogens on surfaces in dental practices nor did it determine the
optimal interval for disinfection of these surfaces. The rate of re-infection of a disinfected surface may vary from
site to site as will the effectiveness of the disinfection effort. This study did not evaluate whether the species
related to MDROs were resistant to a broad spectrum of antibiotics. The intent of the study was to demonstrate
the potential for these organisms to exist on surfaces within a dental practice.
Compliance
Compliance with standard infection control methods (disinfecting on a regular basis, washing hands, avoiding
potential contamination from vectors [organisms that transmit pathogens], not having food/ coffee at the desk,
leaving treatment areas with gloves on or using a gloved hand on a keyboard/mouse, chart, or radiographs) and
a disinterest by some nonclinicians in complying with the protocol were the main difficulties in this study. This
failure to comply with the study protocol could account for the contamination of some of the cleansed keyboards/
mouse devices but it does not invalidate the results reported. On the contrary, this failure to comply with standard
cross-contamination procedures underscores the realities of dental practices and why all staff need to be aware
of contact with potentially contaminated surfaces. In-service training and reinforcement of disinfection standards
may be helpful in reducing the level of pathogens in environmental reservoirs and in eliminating
crosscontamination in the dental office. But in-service training intrinsically does not eliminate the necessity for
caution. Although careful attention was given to in-service training of nonclinical personal in this trial our
observations illustrate the all-toocommon failure to adhere to cross-contamination guidelines.
Patient charts and radiographs are vectors that cannot be disinfected. Although charts and radiographs should
not be in treatment areas, the fact is they often are. The reality in many practices is that charts and radiographs
are occasionally touched with the gloved hand, exposed to aerosol from handpieces, passed to the front desk,
and taken from room to room and to the dentist's desk. Certainly they find their way several times a day to a
keyboard where a staff member can enter data from the chart. After disinfection of keyboards, mouse devices,
phones, desktops, and pens, the staff member who enters the data at the computer may immediately
contaminate that station. For example, he or she may receive a chart from a clinician and enter data in the
computer, take money or checks from patients, answer the telephone, or go to a station that may not have been
disinfected, such as the copy machine.
Other areas of possible contamination are gowns and clothing, blood pressure cuffs, hand-held computer
devices, cell phones, and pens. Infection from cross-contamination of these sites to the patient or from the
patient to these sites may occur if basic contamination containment practices are not followed by all members of
the dental health care team— regardless of whether their duties are clinical or office-related.
Clinicians and staff are generally aware that they have a risk of contracting infections from patients when they
are not protected with barriers such as masks, gloves, full shield eye protection, and gowns. Barriers such as
gowns, gloves, masks, and eye/face protection should be sufficient to protect patients and dental health care
providers chairside regardless of the level of contamination of surfaces outside the operatory. However, since it
is virtually impossible outside the operatory to avoid coming in contact with organisms on patient charts and
radiographs, front desk surfaces, telephones, pens, computers, etc, dental staff need to take precautions. It may
sound simplistic but the single most effective recommendation for preventing contamination is to wash hands
frequently throughout the day, before and after gloving, before eating, and before leaving the dental practice
environment.10,15,19,20 The Centers for Disease Control and Prevention recommendations state: "In health care
settings, handwashing can prevent potentially fatal infections from spreading from patient to patient and from
patient to health care worker and vice-versa. The basic rule in the hospital is to cleanse hands before and after
each patient contact by either washing hands or using an alcohol-based hand rub."19,20
Recognition of potential reservoirs of bacterial contamination within the dental office, following basic hygiene
precautions such as washing hands, and the use of barrier procedures chairside can reduce the risk of MDRO
transmission to dental patients and dental health care providers.
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Roger V. Stambaugh, DMD, MS, MSEd, FACD, is in private practice dedicated to
periodontics and implantology in Burlington, Wash. He is a Diplomate of the American
Board of Periodontology and former director of Graduate Periodontics at the University
of Southern California School of Dentistry, Los Angeles. Stambaugh is also a
Dimensions of Dental Hygiene Editorial Advisory Board member.
Leanne Elson, MS, M(ASCP), is a microbiologist and laboratory manager at Medical
Diagnostic Laboratory Inc, Mount Vernon, Wash, a comprehensive clinical laboratory
that provides microbiology, blood, urine, cytology, and pathology testing and drug
screening.
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