The effectiveness of hand hygiene procedures in reducing the risks ...

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S46 Vol. 35 No. 10 Supplement 1 Bloomfield et alTable 11. Efficacy of handwashing and alcohol-based hand sanitizers in preventing transfer of hepatitis A and felinecalicivirus from fingertips to lettuceHepatitis AFeline calicivirusParticles transferredto lettuce, %Particles remainingon hands, %Particles transferredto lettuce, %Particles remainingon hands, %No treatment 9.2 18Handwashing 0.39 6.5 0.4 762% Ethanol, 20 seconds 0.64 64 2.1 1375% Ethanol, 20 seconds 0.46 24 1.2 17homemakers in New York 180 showed that a singlehandwash had little impact, with mean log counts of5.72 before compared with 5.69 after handwashing.Another study with 52 office workers and studentsshowed a mean log prewash count of 4.81 comparedwith 5.07 postwash. 181 Kampf and Kramer 173 also reviewedstudies from health care settings in which increasedbacterial counts were found on the handsafter handwashing, and handwashing failed to preventtransfer of bacteria from hands to surfaces. Althoughthere are no data available to confirm this, increasesin contamination may result from sweating inducedby hot water, which flushes resident bacteria fromthe sweat glands onto the hand surface or aids detachmentof bacteria attached to skin scales.It is important to bear in mind that, although soapand water removes contamination from the hands,soap itself has a limited antimicrobial effect, whichmeans that contamination will be transferred to thesink. Hospital studies show that Pseudomonas aeruginosaand Burkholderia cepacia 182 can form reservoirsof contamination in sink waste pipes and can be asource of infection at times when splashes of contaminatedwater come in contact with hands. Mermel et alreported that hands of HCWs became recontaminatedfrom faucet handles during a Shigella outbreak. 183Soap bars also have the potential to spread contaminationfrom person to person via the hands. 88Efficacy of ABHSABHS are formulations that contain either ethanol 1-propanol or 2-propanol or a combination of these products.Their antimicrobial activity is attributed to theirability to denature proteins. Although products containing60% to 95% alcohol are most effective, higherconcentrations are less effective because proteins arenot easily denatured in the absence of water. A rangeof in vivo and in vitro studies have been carried outto determine the effectiveness of ABHS and are reviewedby Boyce and Pittet, 172 Kampf and Kramer, 173and Sickbert-Bennet et al. 169In vivo panel testing of ABHS. In Europe, the efficacyof ABHS is established by panel tests that determinethe reduction in the number of organismsreleased from artificially contaminated hands. Thetest applicable to ABHS is the Committee EuropeanNormalisation Hygienic Handrub Test EN1500. 184 Inthis test, E coli is inoculated onto the hands and dried.The sanitizer is applied to the hands with a rubbingaction for a specified period. The residual number ofbacteria present on hands is assessed pre- and posttreatmentby a rinse-sampling process and the logreduction determined. To claim that a product is a hygienichandrub, it must produce a log reduction at leastequivalent to that produced by a reference productcontaining 60% vol/vol 2-propanol (mean, 4.24 log in1 minute; range, 3.17-6.46).In vivo panel testing against bacterial strains. Data fromin vivo panel tests, summarized in Table 12, indicatethat ABHS show good and rapid activity against bacterialstains such as E coli and S aureus. Efficacy is atleast as good, if not better, than that achieved byhandwashing with soap (Table 10); log reductions obtainedafter a 30-second contact period were of the orderof 3.4 to 3.7 or more compared with 1.8 to 2.8 fora 30-second handwashing process. Boyce and Pittet 172conclude that, typically, log reductions of the releaseof test bacteria from artificially contaminated handsaverage 3.5 log after 30 seconds and 4.0 to 5.0 logafter 1 minute.Paulson et al 185 compared the efficacy of ABHS containing62% ethanol (contact time 5 minutes) withhandwashing against S marcescens, which showedthat handwashing (20 seconds rubbing followed by30 seconds rinsing) produced a log reduction of 2.29compared with 3.83 for the ABHS. Hammond et al 186recorded a 2.84-log reduction for 62% ethanol againstS marcescens in 10 seconds using the ASTM method.Sickbert-Bennet et al, 174 however, showed that exposureof S marcescens to 60% to 62% ethanol for 10 secondsproduced only a 1.15- to 1.55-log reductioncompared with 1.87-log reduction for handwashingfor 10 seconds, when tested by the ASTM 1147method.
Bloomfield et al December 2007 S47Table 12. Efficacy of alcohol-based hand sanitizers inreducing the release of bacteria from artificiallycontaminated handsAgentConcentration(%)TestbacteriumMean log reductionexposure time (min)0.5 1.0 2.01-propanol 100 E coli - 5.8 -60 - 5.5 -50 3.7 4.7 4.940 - 4.3 -2-propanol 70 E coli - 4.9 -3.5 - -60 E coli - 4.0-4.4 -S marcescens - 4.1 -50 E coli 3.4 3.9 4.4Ethanol 80 E coli - 4.0 -70 3.4-3.6 3.8-4.3 4.5-5.1S aureus 3.7 - -60 E coli - 3.8 -Leischner et al 187 carried out in vivo tests thatshowed that alcohol gels were significantly less effectiveagainst C difficile spores (1.68- to 1.94-log reduction)compared with handwashing with chlorhexidinesoap (2.46-log reduction). Residual spores were readilytransferred by handshaking following ABHS use. 187The reduction in spore counts is higher than expectedin view of their known resistance to alcohol and mayresult from the friction associated with application ofthe gel rather than a bactericidal action; Kampf andKramer 173 state that water alone can produce a reductionof 0.5 to 2.8 log within 1 minute for E coli.Using the standard ASTM 1174 method, Sickbert-Bennet et al evaluated the effect of exposure timeand volume of product used on the efficacy of 62% ethanol.169 They showed that the use of 7 g of the ABHSproduced a higher log reduction compared with 3 g(2.7- to 3.8-log reduction compared with 1.0- to 1.8-log reduction). Rubbing the hands until dry (3-12 minutes)was more effective compared with a 10-secondapplication (1.0- to 1.6-log reduction compared with0.6- to 1.1-log reduction).Two recent field studies indicate that an ABHS isequally or slightly more effective than handwashing inreducing bacterial contamination on hands. Davis etal 19 compared the reduction of bacterial counts onhands using soap and water or a 62% ethanol-basedhand sanitizer (contact time 30 seconds) after animalhandling at a US livestock event. There was no significantdifference in the distribution of log reductions obtainedusing ABHS compared with handwashing; logreductions in total count ranged from 21.4 to 1.4 and23.0 to 3.5 for total coliforms. Traub-Dargtz et al carriedout a study at 2 clinics in Canada to evaluate the efficacyof handwashing compared with use of ABHS (62% ethanol,contact time 30-60 seconds) on veterinary staffperforming routine equine physical examinations. 188Mean bacterial load on hands increased by 0.36 and0.91 log (for the 2 clinics, respectively) as a result of handlingthe animals, whereas the mean log reduction producedby handwashing with soap was less than 0.6,compared with 1.29 and 1.44 log (for the 2 clinics, respectively)produced by ABHS.In vivo panel testing against viral strains. A number ofin vivo studies have been carried out to determine theefficacy of ABHS in reducing the release of viruses fromhands. Test methods were variants of the method of Ansariet al 189 or the ASTM E1174 method, 171 in which thevirus is applied to the fingertips and the efficacy of theproduct in reducing the numbers of viral particles recoverablefrom the hands determined. The residualnumber of viral particles present on the hands is assessedpre- and posttreatment and the log reductiondetermined. Data collated by Boyce and Pittet 172 (Table13) indicate that ethanol at 60% to 80% produces a0.8- to .3-log reduction against a range of viruses,the extent of the reduction depending on the viralstrain, the nature and concentration of the alcohol,and contact time.Data indicate that activity of ABHS against viralstrains is less than against bacterial strains and thatethanol has greater activity against viruses than 2-propanol.However, all of the strains referred to in Table 13are nonenveloped viruses, which are known to be moreresistant to disinfectants than enveloped viruses. As faras hand hygiene in the home and community is concerned,however, this is key because many of the viralstrains responsible for hygiene-related ID commonlyoccurring in community settings (rotavirus, norovirus,rhinovirus, and adenovirus) are nonenveloped. Thathaving been said, the data suggest that, although nonenvelopedviruses such as HAV and enteroviruses(eg, poliovirus) require 70% to 80% alcohol to be reliablyinactivated, studies by Sattar et al 194 suggest that60% ethanol was sufficient to reduce the titers of rotavirus,adenovirus, and rhinovirus by .3 log within a10-second contact period. Data indicate that FCV mayalso be relatively susceptible to alcohols comparedwith other nonenveloped viruses, although sensitivitydepends on the type and concentration of alcohol. Usingan in vivo test based on the ASTM 1838-02 method,Gehrke et al 190 showed that 70% ethanol was the mosteffective agent against FCV with a log reduction of 3.78compared with 70% 1-propanol (log reduction, 3.58)and 70% 2-propanol (log reduction, 2.15) (exposuretime 30 seconds). However, a more recent study byKampf et al 191 suggested a log reduction after 30 secondsof only 2.66 and 1.53 for 70% ethanol and 70%1-propanol, respectively.
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