Hindawi Publishing CorporationBioMed Research InternationalVolume 2013, Article ID 429780, 8 pageshttp://dx.doi.org/10.1155/2013/429780

Research ArticleEnvironmental Contaminants in Hospital Settings andProgress in Disinfecting Techniques

Gabriele Messina,1 Emma Ceriale,2 Daniele Lenzi,3 Sandra Burgassi,1

Elena Azzolini,2 and Pietro Manzi3

1 Laboratory of Environmental Hygiene, University of Siena, Italy2 Post Graduate School in Public Health, University of Siena, Italy3 Teaching Hospital Le Scotte, Hospital Direction, Siena, Italy

Correspondence should be addressed to Gabriele Messina; gabriele.messina@unisi.it

Received 30 April 2013; Accepted 17 September 2013

Academic Editor: Marc Leone

Copyright 2013 Gabriele Messina et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Medical devices, such as stethoscopes, and other objects found in hospital, such as computer keyboards and telephone handsets,may be reservoirs of bacteria for healthcare-associated infections. In this cross-over study involving an Italian teaching hospitalwe evaluated microbial contamination (total bacterial count (TBC) at 36C/22C, Staphylococcus spp., moulds, Enterococcus spp.,Pseudomonas spp., E. coli, total coliform bacteria, Acinetobacter spp., and Clostridium difficile) of these devices before and aftercleaning and differences in contamination between hospital units and between stethoscopes and keyboards plus handsets. Weanalysed 37 telephone handsets, 27 computer keyboards, and 35 stethoscopes, comparing their contamination in four hospitalunits. Wilcoxon signed-rank and Mann-Whitney tests were used. Before cleaning, many samples were positive for Staphylococcusspp. and coliforms. After cleaning, CFUs decreased to zero in most comparisons. The first aid unit had the highest and intensivecare the lowest contamination ( < 0.01). Keyboards and handsets had higher TBC at 22C ( = 0.046) and mould contamination( = 0.002) than stethoscopes. Healthcare professionals should disinfect stethoscopes and other possible sources of bacterialhealthcare-associated infections. The cleaning technique used was effective in reducing bacterial contamination. Units with highpatient turnover, such as first aid, should practise stricter hygiene.

1. Introduction

The Centre for Disease Control (CDC) defines a health-care-associate infections (HAIs) as a localized or systemiccondition resulting from an adverse reaction to the presenceof an infectious agent(s) or its toxin(s). There must be noevidence that the infection was present or incubating at thetime of admission to the acute care setting. HAIs maybe caused by infectious agents from endogenous (bodysites) or exogenous sources (patient care personnel, visitors,patient care equipment, medical devices, or the health careenvironment) [1]. Every year, millions of people across theworld suffer from HAIs. HAIs are a wide-ranging concernin the medical field, not only because of morbidity and thepossibly of lethal consequences for patients, but also becauseof extended hospital stays and associated high costs [25].

In Europe HAIs cause 16 million extra days of hospital stayand 37000 attributable deaths; they determine approximatelycosts associated of C 7 billion annually. In the USA around99000 deaths were attributed to HAIs in 2002 and associatedcosts were approximately US$ 6.5 billion in 2004 [5, 6].

A Europe-wide point prevalence survey estimated that atleast 2.6 million cases of HAI occur annually in long-termcare facilities, in addition to ECDCs earlier estimated at 4.1million patients acquiring HAIs in acute-care hospitals [7].

These infections often have little or nothing to do withthe primary reason for the hospital visit but are a result ofpoor or inadequate hygiene in the healthcare setting [8].Healthcare equipment is frequently shared between hospitalstaff, who may have different hygiene practices. Medicaldevices (stethoscopes, otoscopes, and thermometers) andvarious objects in hospital environments, such as telephones

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and computers, have been associated with transmission ofHAIs [918]. Stethoscopes/phonendoscopes (stethoscopes)are medical devices frequently used in direct contact withpatients skin and can therefore be a vector of infections.These occurrences are known to the scientific communityand testified by numerous international studies [9, 11, 1618].Physicians should disinfect stethoscopes between one patientand another, though unfortunately this good practice is notalways implemented.

Computers and telephones are now tools ofmedical prac-tice and are found in all healthcare settings.Their disinfectionis often neglected more than that of medical devices. Severalstudies demonstrate major contamination of these objectsand a possible role in the transmission of infection [13, 15].Current scientific knowledge suggests that the disinfection ofenvironmental surfaces in modern hospitals is indispensable.Furthermore other simple measures, such as hand hygieneof medical staff, remain of a great impact to avoid HAIs[19]. Various studies have investigated singly the role ofstethoscopes, computer keyboards, and telephone handsetsin HAIs [913, 15, 16]. To our knowledge there is lack ofresearch on the evaluation of all these devices together, indifferent units of the same hospital, where there should be aspecific organizational model and risk factors [8] with regardto HAIs. The aims of the present study were to evaluate (i)the contamination of stethoscopes, computer keyboards, andtelephone handsets in an Italian teaching hospital before andafter use of a disinfecting technique (DT); (ii) differencesin contamination in four hospital units; (iii) differences incontamination of medical devices used in clinical practice(stethoscopes) and tools used in medical practice (computerkeyboards and telephone handsets).

2. Materials and Methods

2.1. Setting. We conducted a cross-over study in an Italianteaching hospital with 750 beds in Siena. A variety ofhospital environments [8] were chosen to consider differentcharacteristics: emergency unit and first aid which have ahigh turnover of patients and disinfection of the environmentcannot always be pursued effectively, intensive care whichobserve aseptic conditions and most patients are at high riskof developing infections, and cardiology/hemodynamicwhich aremedical units and have rooms withmore beds thanthe intensive care unit and are frequented by many visitors.

Before the study began, meetings were held between thehospital management and the principal researcher. This iswas necessary to explain the project, establish the necessarycontacts and avoid any bias in conducting the study. It wasconsidered important to avoid bias caused by doctors/nursesknowing when the investigation would be run, as this mightprompt changes in hygiene. It was also decided that stetho-scope sampling would be on the same day in each unit, toprevent news of the study circulating andmodifying hygienicpractices.

2.2. Disinfecting Technique. We conducted a surface chal-lenge test to determine the capacity of the disinfectant in

killing bacteria and mould [20]. For the cleaning and disin-fection of these objects we used a putty compound having amalleable elastic consistency that adheres, removing dirt anddisinfecting at the same time. These two characteristics dis-tinguish this disinfecting technique from traditionalmethodsof cleaning and disinfection, aspects normally achieved usingtwo separate operations. The main sanitizing principle of theputty is ethanol (29%) and other components are purifiedwater (51%), guar (6%), glycerine (7%), and minor quanti-ties of other substances, such as boric acid, colorants, andodorants. These features make the putty particularly usefulfor cleaning and disinfecting surfaces with indentations andprotrusions, such as keyboards and handsets. The techniquedisinfects, as demonstrated by studies conducted accordingto the indications of the U.S. Pharmacopeial Convention(USP), Chapter 1072 Disinfectants and antiseptic andaccording to CONFARMA protocol number 229100911 A-B which is based on (i) guidelines of the Germany Societyfor Hygiene and Microbiology 1991, (ii) European standardsEN 1040 Chemical disinfectants and antisepticsBasic bac-tericidal activityTest method and requirements (phase 1),and (iii) EN 13697 Chemical disinfectants and antisepticsQuantitative non-porous surface test for evaluation of bacteriaand/or fungicidal activity of chemical disinfectants used infood, industrial, domestic and institutional areasTestmethodand requirements without mechanical action (phase 2/step 2)[21].

2.3. Data Collection. It was decided to study almost all thestethoscopes, computer keyboards, and telephone handsetsfound in the four units. We analysed 99 objects: 37 tele-phone handsets, 27 computer keyboards, and 35 stethoscopes(including shared and nonshared ones).

The experimental protocol required a first sample (swab)H(0) from one-half of each stethoscope membrane, key-board, and telephone handset, before cleaning with theputty, and a second sample H(1) from the other half of thesame objects after cleaning. The swab H(0) was necessaryto evaluate the initial contamination level [20]. Sampleswere obtained by swabbing the surfaces with sterile cottonpads for approximately 5 seconds per stethoscope, 2030per keyboard, and 1520 per telephone. These swabbingtimes were established according to the different size ofthe objects. Cleaning half of the stethoscope diaphragm,computer keyboard, and telephone handset with the producttook about 2025 seconds, 24 minutes and 2030 seconds,respectively, depending on dirtiness.

Taking samples, at H(0) and H(1), from both halvesof the stethoscopes, keyboards, and telephone handsetswas important to avoid the possibility that the first swabsremoved bacteria physically, reducing the amount of bacteriacollected by the second swab from the same surface andpreventing true assessment of product efficacy in reducingbacterial/mould contamination. Because the twohalves of thekeyboard are different and some keys are used more thanothers (e.g., enter) we decided to alternate the side to whichthe product was applied.

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All doctors/nurses encountered during the visit to theunits were informed by the principal researcher/hospitalmanagement doctor of the study and were asked if therewas any problem about carrying out the study; there wereno objections. A new pack of product was used for everyobject. The following information was also recorded at thetime of sampling: hospital identification (ID), department ID,and doctor/nurse ID. Records were indexed with a unique IDfor each sample. The same ID was assigned to the pack ofcleaning putty. All the information was recorded and storedin a database for future analysis.

2.4. Laboratory Analysis. Analysis was carried out in theHygiene and Environmental Laboratory of the Universityof Siena, where the swabs were placed in 1mL phosphatebuffered saline, shaken in a vortex mixer and the liquidsown (0.1mL/plate) in Petri dishes containing plate countagar (PCA) for total microbial load incubating at 36C formesophilic germs (human contamination) and at 22C forpsychrophilic microorganisms (environmental contamina-tion). Index microorganisms were cultured in mannitol saltagar for Staphylococcus spp. (hand-transmitted pathogens),Pseudomonas cetrimide for Pseudomonas spp. faecal contam-ination), Slanetz & Bartley medium for Enterococcus spp.(faecal contamination), Brilliance E. coli/coliform spp. chro-mogenic medium for Escherichia coli and coliform bacteria(faecal contamination), Acinetobacter base for Acinetobacterspp. (an emerging alert for HAIs), and Brilliance methicillin-resistant Staphylococcus aureus (MRSA) MRSA2 mediumfor methicillin-resistant Staphylococcus aureus incubating at36C (Staphylococcus aureus resistant to methicillin antibi-otics). Clostridium difficile agar base was supplemented withClostridiumdifficile selective supplement and 7%defibrinatedhorse blood for Clostridium difficile spp. (as an indicator ofpoor disinfection) with incubation for 48 hours at 36C inan anaerobiosis jar. Anaerobiosis was obtained using a gasgenerating kit.

All the sowings were made by the same technician ofthe Department of Physiopathology, Experimental Medicineand Public Health involved in the study. The Petri disheswere read by the principal researcher and the technician.The results were expressed as colony-forming units perswab (CFU/0.1mL). The plates were read 24 and 48 hoursafter sowing. We opted for a double count: at 24 hoursto prevent vigorous bacterial growth from rendering somecolonies uncountable at 48 hours and at 48 hours to avoidmissing bacterial species/colonies with slower growth. Allbacteria/mould counts were added to the previous databasefor further use.

2.5. Statistical Analysis. Database cleaning was performedbefore data analysis. Descriptive analysis (mean, standarddeviation, median, interquartile range, minimum, and max-imum) of the data for all types of microbes/moulds wasperformed for H(0) and H(1). For each bacterium, wecounted the number of positive samples for H(0) and H(1)and calculated their percentages. We also calculated the totalquantitative CFU count of the 99 objects for H(0) and H(1)

and the percentage reduction after use of the experimentaldisinfecting technique. The matched approach used (twohalves of each object, one before and one after cleaning)aimed at better control of confounders, minimizing theireffects and increasing the reliability of the results. WhenCFUs of H(1) were not zero, statistical tests were carriedto highlight differences between before and after cleaning.Descriptive analysis forH(0) was also conducted at ward levelto determine contamination load. To reveal differences inbacterial contamination before and after use of the productthe Wilcoxon signed-rank test was used, while the Mann-Whitney test was used to detect differences (i) between units,(ii) between telephone handsets plus computer keyboardsversus stethoscopes, and (iii) between personal and sharedstethoscopes [22].

Significance was set at < 0.05. Stata SE, version 12.1software (StataCorp, College Station, TX, USA), was used forthe analysis.

3. Results

Descriptive statistics are shown in Table 1. Mean, median,interquartile range, and standard deviation were obtainedconsidering only positive samples.The percentage of positiveH(0) samples was generally higher on computer keyboards,followed by telephone handsets and stethoscopes. The onlyexception was MRSA, where the latter had a higher per-centage of positive samples: 28.6% compared to 16.2% fortelephone handsets and 22.2% for computer keyboards.

No H(0) or H(1) samples contained Pseudomonas orClostridium difficile (only investigated on stethoscopes).CFUs decreased to zero in most comparisons.

For stethoscopes, significant CFU differences weredetected in PCA 36, PCA22, Staphylococcus spp. (