HealthManagement, Volume 14 - Issue 3, 2014

The Sanitation of Hospital Stays: New Strategies For The Reduction of HAIs

Authors

Prof.Sante Mazzacane

Department of Architecture

University of Ferrara, Italy

email:  [email protected]

 

Dr.Gianfranco Finzi

ANMDO National President

 

Prof.Luigi Aparo

ANMDO National Scientific Secretary


Co-Authors

Pier Giorgio Balboni

Alberta Vandini

Luca Lanzoni

Maria Teresa Camerada

Maddalena Coccagna

CIAS, Centre for the Study of physical, chemical and microbiological Contamination of Highly Sterile Environments, Department of Architecture, University of Ferrara

 

Paola Antonioli 

Sant’Anna University Hospital of Ferrara, Infection Prevention Control and Risk Management Department, Ferrara

 

Alessio Branchini

Department of Life Sciences and Biotechnology, University of Ferrara

 

Daniela Platano

Department of Biomedical and Neuromotor Sciences, University of Bologna


Key Points

  • This article addresses the issue of sanitation of hospital stays and criticalities inherent in the techniques commonly used for cleaning surfaces and furnishings
  • Experimental research proposes a new intervention protocol which involves the use of a sanitising probiotic product containing Bacillussubtilis, Bacilluspumilus and Bacillusmegaterium in the vegetative and spore form
  • Compared to customary cleaning techniques, tested surfaces showed an 80% reduction of pathogenic agents with the use of the new cleaning protocol
  • This P.C.H.S. (Probiotic Cleaning Hygiene System) also offers directeconomic benefits, with savings of about5-15%compared to traditionaltechniquesofchemical disinfection

Reseach findings are based on in vitro and in situ trials


Introduction

Sanitising procedureshave theprimarypurpose ofreducing and containingthe proliferation ofmicroorganisms existingin hospital environments.


Healthcare-associated infections(HAI) are one of themost frequent complicationsthat can occur inhealthcare facilities.5% -15% of all hospitalised patientsmay developat least oneHAIduring hospitalisation[1].


Threestudies conducted inItalyhave shown a frequencyof 6.7%of theHAI[2], with a prevalence of infections of thelower respiratory tractfollowed byurinary tract infections. In 1998, theItalianNational Health Planidentifiedthe reduction ofhealthcare-associatedinfectionsasa priority [3].


Oneof the most controversialand debated issue is the quality and quantityrole of the environmental contextin the process ofpatient contamination,in particular the roleof theconfiningsurfacesandfurniture.Indeed, it is known thatthese surfacesact asreservoirs[4] for the microorganisms, increasing the risk of cross-contaminationthrough direct contactand /or indirect contact withthe patient.


For this reason,sanitation proceduresare carried out on all the furnitureand objectsthat  may interactwith people.


Commonly,thesetechniques usechemical disinfectants, withthe consequent risks forthe environment andforthe safety of users, andwith considerablecriticaloutcome[5].


There are several factorsthat determine the biocide effectivenessof achemical disinfectant: the contact time, concentration, temperature, pH, the presenceof organic materialand the type ofmicroorganism,and thisis emphasisedto dispelthe myth thatanydisinfectant can be used to sanitiseanysurface.


Therefore, sanitation procedurescarried outby the use ofchemical disinfectantshave several disadvantages, due to:

  • The limited biocidal efficacy over time, which normally runs out within 20-30 minutes after application, with subsequent exponential growth of microbiological agents; this is also due to the fact that the action of the disinfectant determines the production of organic material decomposition, that is nutritional material, which promotes the proliferation of the microorganisms;
  • Thedifferent effectivenessof the disinfectanton the basis ofphysical - chemical characteristicsof the treated surface;
  • The capacity, by microorganismsthemselves,to developcontinuous genetic mutation anddefensesof a different kind, with the purpose tomake the chemicalbiocidal actionineffective, withtheconsequent phenomena ofbiocideresistance, well described in literature;
  • The problemsof allergens and of natural environmental pollutiongenerated bymassivechemicals use that can accumulatein apersistentway in thelargenatural reservoirs(soil,water, air).


All this hasalso resulted ina process ofnatural selectionof the microbial pathogenic strains, increasingly resistantto commondisinfection techniques.


Recentexperimental studieshave identifiedthe possibility of usingnew methods ofsanitisation[6] [7], which exploit the"principle of biologicalcompetition," using probiotic products(PIP)-consisting ofBacillussubtilis, Bacillusmegateriumand Bacilluspumilusvegetativeformandspore-withnon-pathogenicmicrobial load, able to colonisethe surfaces onwhich they are applied, counteracting the proliferation ofother bacterial speciesbased on theprinciple ofcompetitive exclusion(law ofGause, 1934).


This principlelies in the factthat two differentspecies(bacterialand /orfungal),insisting on the sameecologicalmicrocosm, cannot coexistin stable equilibriumif they referto the samenutrient substrates, butone of them,usuallythelessdemandingnutritional factorsbecomedominantover the other, being able toalso causeextinction.


Fromamicrobiological point of view,forthe surfaces treated withprobiotic products,theexistingbiofilmisin factreplaced by a newtype ofbiofilm, mainly formed by thenovel microorganismsartificiallyplacedwiththe cleaning products.


These procedures canthenbeconnotedas" bio-stabilisation techniques " of one speciesover another, thereforeimplyingnota biocidalgeneralised action, ifnot as afinal effectagainst specificmicrobial species.


The recentavailability of these biostabilising products, hence used forsanitising/sanitationof surfacesand for the resident microbial load control, suggested to conductan extensiveexperimental researchaimed toa qualitative and quantitative verification, both "in vitro" and"on the field", of their effectivenessover the useof traditional treatmentsbased onchemical disinfectants.

 

Research Classification

The effectiveness of the procedures used was assessed by comparing the value of the potentially pathogenic bacteria load, detected on the surfaces of nosocomial environments treated with PIP products, compared to the similar charge obtained  with traditional products and by calculating the consequent percentage difference.

The microorganismsinvestigatedwerethose considered mostattractive in termsof hospital infections: Staphylococcusaureus, Pseudomonas species, coliforms (includingEscherichia Coli), Candidaalbicansand Acinetobacterspp..Currently, furtherexperimental investigationsrelating toClostridiumspp., are ongoing.

The study wasconductedboth with in vitro and within situ testsindifferenthospital structures.


In Vitro Trials

The purpose of the "in vitro" trials (UNI ISO 13697:2001) was to assess the effectiveness of competitive products PIP compared to other bacterial species in the absence of any external noise (in the laboratory), i.e. those recontamination processes of treated surfaces which naturally occur in the environment occupied by human.

In-vitro experiments were conducted by treating samples of materials found in hospital areas (i.e., ceramic, PVC, rubber, vitreous-china) with the probiotic-based solution. A solution containing a known concentration (30 X 106 cells/ml, 15 ml/m2) of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains was used for the contamination of sampling surfaces. The bacterial load was measured by the determination of colony count on RODAC plates (BD), containing TSA medium added with lecithin, histidine and Tween-20, in order to neutralise the action of disinfectants. The number of colonies was determined as total microbial count (TMC), or as specific colony count by exploiting strain-specific medium. The control plates for sterility (1 plate/lot) have been used.

After 1 hour from the application of the products PIP on sample surfaces previously polluted with various microbial strains, the reduction of the concentration of the pathogens was found to be 7 logarithms (99.999%) compared to the initial count.

 

In Situ Trials

Tests onreal fieldconcerned variousItalian hospitals; the Sant’ Anna Hospital of Ferrara and the “Arcispedale Sant’Anna” of Cona (Ferrara), the S. Giorgio Hospital of Ferrara, the  Delta Hospital of Lagosanto, and the Hospital ofLokeren(Belgium).


The first experimentswere conductedin 2011in some areasof the plantcare of the “ArcispedaleSant’ Anna” Hospital, with the aim of verifyingthe actionexerted byPIPinnosocomialrealconditionsandthenunder continuousphenomenaofrecontaminationof the treated surfaces.


That study was intentionallyconducted in not newly builthospital environmentsandfree from a filtration and air mechanical ventilation plant, in order to makethe most criticalprocessesof pollution.


Two differentcare areasof the S.AnnaHospitalof Ferrara were thenidentified,the first of whichconsists ofan area of​​inpatientgeneral medicineand the second oneof a clinic area.


Sincebotharedivided intotwo divisionseach (Hall S andHallTin the first caseandOphthalmology/Cardiologyand Orthopedicsin the second case), it was possible toconduct aparallelexperiment, applying the protocolinvolving the useof probioticsin one of the twodepartmentsandthe protocol withtraditional productsin the other departmentof the same area.


The productsused in the protocolweretraditionalchlorine-based, while the probiotic productused wasthe productmarketed byChrysal(Lommel, Belgium)


This allowed result comaprison ofdifferent methods ofsanitationinareas(of the same area) withthe sameintended use,type of useandcontamination characteristics.


Atpredeterminedtime intervals, the values​​of the bacterialpathogenof interestobtainable bythe two differentcleaning systems, were detected


Toverifythereproducibilityof the results, it was decided toreverse the type of cleaning processacross each area departments after 1 month,  (as shown in Table 1), then continuing the experimentsfor another month.


The monitoring campaignswere conductedatregular intervals(almost every 2-3 days) bothat 7:00 am, immediatelyafter the interventionofsanitation, and at 2:00 pm.


Eachsampling wasperformed three times, usingRodac contact plates. Thesamplingswere conductedat different pointsof the concerned departments,asschematised:

  • Beginning ofthe floor of thecorridor leadingto the Department;
  • End ofthe corridor floor;
  • Toilet Floor;
  • Toilet Sink.

The first two pointsremained the sameduringthe wholeexperiment,whilethose onthe floor and thesinkof the hygienic servicewere chosenrandomlyfrom time to time, in order to faithfullyrepresentthe average stateof contamination ofthe entiredepartment.


Microbiological samplesfor the evaluationnot only of thetotal microbial loadbutalsotheexistinginitialmicrobial loadofpotential pathogens were performed in advance.Thistime it wasreferred to astimezero(T0  at 2:00 p.m.).

The trialcontinued witha thirdphase, which began the 22nd July 2011, approximately 1month after the endof the secondphase. In the latterperiod, which lasted up to23rd August 2011, probiotic productsPIPwereemployed,in both departmentsofinpatientmedicine, in order toverifya possiblefurther reductionof the pathogenic chargeafterprolonged periods ofapplication of thePIPs.


Overall,within this firstresearch referring to the Sant’ Anna Hospital, a total of12,528samples were performed.

The sampling procedureof the surfaces and the microbiological analysiswereperformedaccording to the"CONTARP-INAIL Guidelines ", 2005, to the"UNIEN ISO19698:2004" protocol and according to the practicescodifiedin the literature [12].


The use ofprobiotics based protocols, called PCHS,has determined ageneralisedcompressionandstabilisation of the pathogenic chargecompared to the caseof thetraditional procedures. 


Oncethe values​​ofthe microbial loadfor eachsampleandfor eachpathogen were obtained, it was possible to calculatethe average valueforeach phase andfor each protocolsanitisation, and then the percentage reductionof thesamechargein the caseof use of the probiotic-basedprotocolwithrespect tothechlorine-basedproducts(Table 2).


Experimentally,it was observed thata prolonged actionofprobioticsprotocols(over 2 months)allowsasubstantialreduction/containment/stabilisation ofpotentiallypathogenicmicrobial loadcompared to the casein which the environmentsare treated withtraditional products.In manyoccasions thereduction values​​of the microorganismsof interestare closeto 90%, as in the caseof the sink,which represents acritical surfacefor the patient, forthe possibility ofcontact with the handsandother parts of thebody.

 

Further Development of Research Activities

Since thepositiveresultsobtained in the firstphase of the research,the hypothesisofa possible relationshipexisting betweeninfectious events(HAI)andenvironmentalmicrobiology wastested. A secondexperimental research[3], based on an integrated approach between the sanitation methodology(PCHS system-ProbioticCleaningHygiene System) and the good hygienic practices(complianceof the hands), has shown a downward trend with a reductionof more than60% ofinfectious events(HAI) over 14monthsofsamplingin the San Giorgio Hospital ofFerrara.


Having to logicallyimplement an all-out policytomanage therisk of infection, thecleaning protocolwas not limitedto the use ofaparticularsanitiser(the onebased on probiotics), but it has been integrated withaset of coordinate operations. These included, among other things, an adequatestaff training, the use of equipment, mops and materialswith high technological content, as well as a programof checks andcontrols to ensurethe achievement of anappropriate level ofhygiene of the environments.


The analysis of theabove dataandtheavailabilityof the resultsofa large number ofsampling(25.748) overall conducted in differenthospital facilities,actuallyallowsa more systematic and conscious approachof thesanitation practicesof hospital stays.


It wasobserved that,when using thePCHSsystem(with probiotic products)  the following results are obtained:

  • Acompressionof the chargeofpotentially pathogenic microorganismsby over 80% compared to the use of traditional techniquesbased onchemical products;
  • The stabilisation of thissame charge, boththroughout the day,withmuch smalleroscillationsbetween two successivesanitisation, and in the following months after the firstapplication(in particularfrom the thirdmonth).


The trendswere obtainedby applyingthe Poisson analysisand the relatedconfidence intervals.The top confidence intervalrepresentsthe95thpercentile higher (95% of the collected datahas a value thatstandsbelowthis limit), whilethe bottom confidence intervalrepresentsthe95th percentilelower (5 % of the datahas a lower valuethan the one indicated). 


It may be notedthatat month 0, corresponding to the beginningof the first applicationof the PCHS system, and therefore to the value of thecontaminationobtainable thoughthetraditional chemical products, the charge of the microorganismsis significantlyhigher than in therest of the year, witha gradual decreasethatbecomes quitestablefrom the thirdmonth, in which, evidently, thecolonization of theBacillus spp. becomes predominant.


The Evaluation of the Microbiological Contamination

Microbial contaminationis commonlyassessed usingmethods basedon the analysis ofRodac orPetriplates(bycounting the CFUs perunit area) containingselective solid medium or on the non-specific growth.


In literature,the Pitzurra I.M.S. index is a consolidated method (indexofmicrobialsurface), which represents the value of thetotal contamination(CFU/cm2) for the operating rooms[12]. 


This indexis representative, however, of the state of contaminationof a surfacein the instantsimmediately followingthesanitising treatment(30minutes later), this being considered as(chemical) disinfection of the surfacesof interest, or as anindistinct reductionof themicrobiological charge, referring to allmicroorganisms, andnot only to thosepotentially pathogenic.


This parameter, however, does not lend itselfto the evaluationof the resultsoutlined above.
First of all,whilethe operating roomsare consideredareas with highrisk of infection, within which almost the total absence ofbacteria is expected, the same cannotbe said forawardorforaPolyclinic.


Secondly,once the surfaces ofan operating room have been sanitised,the room ispartitioned  and air-conditionedwithabsolute filtration. The processes ofre-contaminationthat occurareattributablesolelyto the natural growthof microorganisms which maysurvivedisinfection.


Conversely,inhospitalisationsthe increaseof the microbial loadismainly dueto the recontamination phenomena caused bythe passage of peopleandmaterials and to thephenomenaofgravitational sedimentationof atmospheric dust.


Thirdly,always talking about hospital stays, it is not useful to establishamaximum threshold valueof contaminationin the time intervalsimmediately followingthe time ofcleaning,since the growth processesof micro-organismshavedynamic nature andinvolvean exponential increase inbacterial countsevenwithin a fewhours.


The evaluationof surface contaminationusingthe methodof the total countof microorganisms(UFC) is thereforenot at all descriptiveof the actualrisk of acquiringinfections for the patient. In the caseof the use ofprobiotics,the microbial populationthat is consolidatedon the surfacessanitised withprobiotic productsis largelyconstitutedby Bacillusspp.considered safefor human health, andonly a smallpercentageis constituted byother bacterial species.


Therefore, it isalwaysconvenient to usethe methodofcountingUFC/m2, per unit area(UFC/m2), butderiving itforsinglepotentiallypathogenicmicroorganism.


Sincethe bacterial loadvaries during time, it is alsoconvenientthat themicrobiologicalsamplesmay be carried outat 2:00 p.m.,that isabout 7hours laterfrom the sanitationmade in the morning,and before thedaily refresher process.


In fact,surveyscarried outby comparingthe different resultsfordifferent timesof the day, lead the results shownin Table 3.


In the chemical protocol, the UFC/m2roughlydoublefrom the first momentsafterdisinfection to about 7hours later; with regards totreatment withtheprobiotic the UFC/m2double or triple(as effectof the recontamination phenomena) from 7hours to 24 hours after the treatment, therefore with akineticsignificantly lowercomparedto the previous case.


24hours aftertheprobiotic cleaningintervention, the contamination with the probiotic protocol is evenhalf ora thirdof the one obtained with the chemical disinfectionin the instant immediately following thedisinfection.
Furthermore,the amplitude of oscillationof the values​​in the caseof probioticsis much morereducedcompared to the alternative protocol, therefore this producesan effect,on the field,of bio-stabilisationofpotential pathogens.

 
Table 1.
The two main drivers, time and economy, The results obtained (25.748 microbiological samples) with the use of PCHS system are exhibited in Figures 1-5.

Proposal of New Indicators of Environmental Hygiene

It is clear that, regardless the mannerwith which it iscarried out,hospitalsanitisationis an industrial type process. Therefore it must be combined witha methodology forverification,onthe field,of the results obtained, withtheconsequent identificationofa scaleof values ​​andcriteria for the acceptabilityof thefinaloutcomes.

It is therefore consideredmethodologically correct toproposethe introduction of aMicrobiologicalQuality Index(IQM) for the measurement of the level ofhygieneof thehospital wards, withtheexceptionof the areasclassified as “highrisk” and the operating rooms. 


The characteristicsof the scaleofmeasurement are as follows:

  • The UFC/m2 represent the measure unit assumed as specimen;
  • The detection of surface contamination is carried out through Rodac plates added with the following selective media : Baird Parker Agar (BD); Cetrimide  Agar ; Sabouraud Dextrose Agar+CFL (SDA) e MacConkey Agar ;
  • Plates should be leaned on the surface to be sampled ; a light pressure must be carried out for 30 sec;
  • The sampling must be performed at least twice (possibly three times ) and the plates , once incubated and read, must be photographed and stored prior to disposal;
  •  The areas sampled are patient contact areas in particular ( nightstand, headboard , etc. ..), and those areas subject to treatment ( inpatient floor , floor corridor of the departments in the maximum transition zones, bathroom floor and sanitary appliances);
  • The UFC/m2 of the single pathogens as Stafilococcus aureus, Pseudomonas species, coliforms (including Escherichia coli), Candida albicans, Acinetobacter spp., Clostridium spp. should be monitored;
  • The UFC/m2 of the total charge must be monitored too (this in order to identify , in case of use of the protocol with probiotics, the presence of Bacillus spp, with the purpose of checking the correct application of the product);
  •  The samples should be performed 7 hours after sanitation (2:00 p.m.), before the daily revision;
  •  The number of samples should allow the achievement of a statistically significant result.

Figure 1.
Staphylococcus aureus load trend.

Figure 2.
Pseudomonas spp load trend.

Based on theresults shownin the previousFigures,it was possible toidentifya scale of values​​for the acceptability ofsanitation procedures, reported in Table4in the case ofuseof probiotics.


Nothingobviouslyforbidsthe use of anyalternative productsto those based on probiotics,as long as they comply with the threshold values​​, above which the resultof thesanitising treatmentis judgednegative.


Thebasic principleproposedconsists in the factthat, regardless of the typeofprotocol chosen, a unique, sharedand objectivemethod should be used, in order to evaluatetheeffectiveness of the treatment, and introducea method of measurementof the results obtained.

Safety of the Probiotics Products

Thegenus Bacillusincludesgram-positive bacteria, which occur in naturein the vegetative formofspore(for this reason are definedspore-formingbacilli); they aresaprophytes,widely distributedinnature(ubiquitous) and they are commonlyisolated fromenvironmentssuch as water,soil(4), air, anddecomposingplant residues.


Among theprobiotic bacteriaof the genus Bacillus, themost studiedspecies, also found in someprobiotic supplements,is theBacillussubtilis[8].


Its genome was completelysequencedadecade ago,and three research studies prove its safetyas a probioticpublished [9-12].


Itsvegetative form, withaerobicandfacultative anaerobicmetabolismand with lownutritional needs, is able to multiply andcolonisethe environmentby competing withotherpotentially pathogenic bacteria.


The spore(Figure 6)instead allowsthe permanence of themicroorganismin the environment duringadverse conditions, maintaining the ability togerminatewhenfavorable conditionsare renewedforthe vegetative form.

The beneficial effectsofB.subtilis spores,as a probioticpreparation, arerelatedto the balanceof the intestinal microflorafor the treatmentor the preventionof intestinal disorders [10].


The dataoninfections caused byB.subtilisare poor, andthe statisticsof the WorldHealth Organisationconcerning thecause of death, do notinclude any. 


The potentialpathogenicB.subtilisis generally described aslow or absent [9,10]. 

Alsoin the  Bacillus subtilisgenome nogenes responsible forthe production oftoxins orother harmful substances,such ashemolysinandlecithinase, were found. In one experiment(6) thesewereadministered for a long time toguinea pigswithout side effects.


All strainsof Bacillusspp. testedaresusceptible to antibiotics [13]. 

The phenomenon ofmicrobialresistanceto antibioticsderivesmainly from thepotentialgene transferby certain bacteria, which possess theseresistance genes, to pathogenic bacteria, which in turn areable to acquireor developresistanceofmultipleantibiotic resistance.


In 2008, a study on antibiotic resistance of the genus Bacillus was conducted; all strains were found sensitive to all antibiotics frequently used in the medical field, as shown by the report of the European Food Safety Authority (EFSA) [14].


Several testsofacute and subchronic toxicity were carried outin animals; studies"in vitro"were performed ona number ofspecies, includingB.subtilisvar. natto(5), B. indicus [9], B. coagulans(19)and B.subtilis2335 [10], without detectinganyside effects.


Bacillus subtilisisused safelyin the production offood typeenzymesand, in the last decade, recombinant strainsof Bacillus subtiliswere usedsafelyin the manufactureof a variety ofedible bio-industrial products, such as enzymes, vitamins, antibiotics, biopolymers, additivesfor the production ofcertain foods such asmisoin Japan(from B.subtilisvar. natto).


The enzymesderived fromB.subtilisare alpha-acetolactate decarboxylase, alpha-amylase, beta-glucanase, glutaminase, maltogenicamylase,pullulanase, proteaseandxylanase.


The B. subtilis is classified as Class 1 (no risk) from the National Institute of Health (NIH - U.S.). [15]; it is nottoxigenicaccording to the criteriaof the U.S. EnvironmentalProtection Agency (EPA) and it is one of10host organismsinTier I that qualify for an exemptionunder theEPA regulationsconcerning theclassificationof risk .

In addition, theB.subtilisis used as asoilinoculantinagricultureandhorticulture.


Some enzymes producedby B.subtilisare widely usedas additiveswithbiological activity of soak cleaningin laundry detergents.


Aremarkable range offermented foodsare also obtained fromthe proteolytic and enzymatic activityof theBacillus subtilis.


TheB.subtilisstrain QST713(marketed asQST 713orSerenade) hasnaturalfungicidal activity, and isused as abiological control agent [19].


The Bacillusspp. based products werepopular all over theworldbefore the introductionof antibiotics assubtilic vaccines, that is as immunostimulating agentsto help thetreatment of diseasesof the gastrointestinal tractand the urinary tract.


In conclusionit can be statedthat the bacteriaof the genus Bacillus, as considered safe, areused in agriculture, [19, 20], horticulture,inhuman nutrition [21] andin veterinary medicine [ 22, 24].


SeveralBacillus specieshave been classifiedGRAS(Generally Regarded As Safe), as used infood processesorin pharmaceutical preparations, and thereforerecognisedby the FDA (Food and Drug Administration) as treatments forhuman purposeswithout side effects [16, 25, 27].


They do notinduce the formation ofpathogenic bacteria, they are biodegradable andenvironmentally safe.[h1] 


Conclusion

The use of the PCHS system, based on probiotics in sanitising procedures of hospital stays , was found to be a technique of great interest, able to reduce by approximately 80% and beyond the levels of potentially pathogenic bacterial load , regardless of the surfaces sanitised. However, a proper cleaning system of hospital stays is not only centered on the specific agent or product used , but on an integrated set of operations and cross-checks which can ensure  health departments in terms of effectiveness of the overall result and the valorisation and quantification of the result.
Figure 3.
Coliformi totali load trend

Figure 4.
Candida spp. load trend. From the use of traditional chemical products (month 0) to the use of the PCHS system, the microorganism load progressively decreases, with a consequent decrease of the risk of infection.

Figure5.
Clostridium difficile load trend.


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Authors Prof. Sante Mazzacane Department of Architecture University of Ferrara, Italy email: [email protected] Dr. Gianfranco Finzi ANMDO Natio...

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