{"paper_id":"438b1691-c2f0-4b41-af10-a6cafd88ceb7","body_text":"1 \n \nImpac t of daily oc tenidine skin w as hin g on antiseptic toleranc e of coa gulase-negativ e \nst a phylococ ci  in two neona t al  inte ns iv e c ar e  units  w it h  differ e nt  ba t hi ng practic es . \nAuthor s:  \n• Heather Felgate 1 ,  \n• Charlotte Quinn 2,4 ,  \n• Ben Richardson 3 ,  \n• Carol Hudson 3 ,  \n• Dheeraj Sethi 4  \n• Sam Oddie 3 ,   \n• Paul Clarke 2,5* ,  \n• Mark Webber 1,2* .  \n \nInst itutions  \n1.\n Quadram Institute Bioscience (QIB), Norwich Research Park, Norwich UK \n2.  Norwich Medical School, University of East Anglia (UEA), Norwich, UK \n3.  Neonatal Unit, Bradford Royal I nfirmary, Bradford, UK \n4.  Norfolk and Norwich University Hospitals NHS Founda tion Trust (NNUH), Norwich, UK  \n5.  Neonatal Unit, Norfolk and Norwich University Hospitals NHS Foundation Trust (NNUH), \nNorwich, UK \n*co-corres ponding aut hors \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \nNOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.\n\n \n2 \n \nCor res ponding  Aut hors \nProf Paul Clarke, Ne onatal Unit, Norfolk and Norwich University Hospital s NHS Founda tion Trust \n(NNUH), Norwich, UK. \nTelephone: 01603 287337 \nEmail: paul.clark e@nnuh.nhs.uk \nProf Mark Webbe r, Quadram Institute Bioscience (QIB), Norwich Research Park, Norwich UK. \nTelephone: 01603 595233 \nEmail: mark.webber@quadram.ac.uk  \n \n \nRunning t itle:  Impact of antiseptic washi ng on neonates  \nKeyw ords : Disinfection, infection control, NICU, CoNS.  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n3 \n \nSumma r y : (250 words) \nBackground: Coagulase Negative Staphylococci (CoNS) are responsibl e for 80-90 % of catheter \nrelated sepsis in neonates which can cause life threatening and damaging effec ts. NICUs within the  \nUK use various practic es to decolonise neonate s to prevent infection ranging from regular full body  \nbathing to localised skin decontamination before insertion of indwelling devices. There i s a disparity \nin bathing prac tices for infants admitted onto neonatal units, with some choosing to regularly ba the  \ninfants and others not, and some routinely washing with skin anti septics, and others not. \nAim: To compare the abundance of CoNS within two UK NICUs with different approaches to skin \nbathing and to test their toleranc es to antiseptics. \nMethods: A collection of CoNS from two UK based NICUs with differing bathing routines for \nneona te s were collated and tested for susceptibility to the antiseptics in use , octenidine and \nchlorhexidine. \nFindings: Regul ar bathing of neonates in octenidine did not dec rease the abunda nce of organisms on \nneona tal skin. Isolates from the unit where octe nidine was in frequent use did not show any \nincreased antiseptic tolerance. Isolates from the unit where regular bathing was not routine practice  \nwere less susceptible to both antiseptics. \nConclusion: Frequent whole-body skin washing with octenidine does not appear to result in a lasting  \nreduction in numbers of organisms found on the skin but also does not appear to select for \nantiseptic tolerant CoNS. \n \n \n \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n4 \n \nIntroduction \nInfection is common amongst premature and low birth weight infants, due to the immaturity of their \ni m m u n e  s ys t e m ,  s k i n  a n d  m u c o s a l  b a r r i e r s  [ 1 ,  2 ] .  L a t e  o n s e t  i n f e c t i o n  ( L O I ) ,  o c c u r r i n g  a f t e r  t h e  f i r s t  \n72 hours after birth, is usually nosocomial and caused by organisms from the skin microbiota or \nhospital environment [3]. Within ne onatal intensive care units (NICUs), invasive procedure s are  \noften essential for management but i ndwelling catheters a re a major source of infection [4]. \nCoagulase-negative staphylococci (CoNS) are common skin commensals, which cause up to 80%–\n90% of LOI in NICUs. Catheter-related sepsi s can be life-threatening and c ause permanent lifelong  \ninjury and disability in survivors, including cerebral palsy and other adverse neurodevelopmental \nproblems  [3, 5-8]. \nCoNS rapidly colonise the  skin of infants after birth, with the  most prevale nt species being S.  \nepi derm idi s, S . h ae moly t i cus  and S.  war n e r i  [9].  Disruption of the skin barrier by implantation of \nintrava scular devices can lead to contamination of the outside of these devices (such as central \nvenous catheters [CVC]). This can then lead to bloodstream and ca the te r-related infections, which \ncan in turn lead to systemic infection and neonatal sepsis [4, 10, 11].  \nAntiseptics are used pre-implantation to minimise the risk of infection at the site of a skin breach. In \naddition, within both adult and paediatric populations, there is evidence that re gular bathing using  \nantiseptics including chlorhexidine gluc onate (CHX) can reduce the number of hospital acquired \ninfections within intensive care [12-14]. However this has not been observed for CHX-ba sed body  \nwashing in neonates[15]. Whilst there are national evidence-based guidelines for antiseptic use  in \nchildren, there is no UK guidance in place for infants who are less than two months old [16]. Due to \nthis lack of UK standardised guidance for topical antiseptic use within NICUs, there are a large range  \nof practices in operation, from regular full body bathing to just local site decontamination before  \ninsertion of indwelling device s[17]. The re is also a wide disparity between different anti septic s and \nfrequency of bathing, with the most common anti septic s used being octenidi ne (OCT), povidone  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n5 \n \niodine and alcohol-/aqueous-based CHX which is frequently u sed in widely varying concentrations \ndepending on hospital protocols [18, 19].  \nCHX is a ca tionic bisguanide with a broad spectrum of antimicrobial ac tivity [20]. It has been shown \nthat regular bathing with CHX significantly reduc es the bacterial skin burden in neonate s [21], \nhowever, the duration of this reduc tion and subsequ ent impact on reducing neonatal bloodstream \ninfections and sepsis, is much le ss clearcut [8, 22, 23]. OCT is a bis-pyridine compound which also has \na broad spectrum of antimicrobial activity. Very few studies have examined the use of OCT within a  \nneona tal population, however there is evidence that it is e ffective at reducing hospital acquire d \ninfection among st adults and older children [24-26]. OCT ha s been introduced as a body wash as it is \nreportedly mild and suitable for patients with vulnerable skin. \nIn this work, we compared antiseptic susceptibility of isolates of CoNS from two UK NICUs; one unit \ncarrie s out regular whole-body washes for infants, using an OCT based anti septic (Bradford Royal  \nInfirmary). The other NICU (Norfolk and Norwich Universi ty Hospital)  does not routinely ba the  \ninfants betwe en admi ssion and discharge.   \nOur hypothesis wa s that CoNS isolates from the skin in infants who undergo daily whole-body skin \nwas hing with OCT will show higher MIC to OCT compar ed to infants who wer e not  r outinely bathed. \nThus primary outcome should be the aim to determine whether routine washing of babies with OCT  \nimpacted the abundance of CoNS isolated from skin, and impacted tolerance to OCT. Secondary aim \nw as  t o  s ee  i f  re g ul a r  w as h i n g  o f  ba b i es  w i t h  O C T  i m p ac te d  t o le r a n ce  t o  C H X  c om pa r e d  w i t h  i n Co N S \nisolates from infants who were not routinely bathed. \n \nAims : To determine whe the r routine w ashing of babies with OCT may impact the abundance of \nCoNS isolated from skin, and tolerance to OCT or CHX. \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n6 \n \nMaterial s and Methods  \nStudy  Sites a nd  r o ut i ne c lean sin g p r ac tic es  \nThis work involved NICUs in two  hospitals; at the Norfolk and Norwich University Hospital (NNUH) \nbathing or whole-body skin cleansing was not practise d routinely on infants. At the Bradford Royal  \nInfirmary (BRI), infants ≥ 26 weeks we re washed daily using Octenisan® (0.3 % octenidine) which was \napplied to the skin using cotton wool  and then washed off water. Infants <26 weeks or with broken/ \nimmature skin were excluded from the regime a s per hospital policy. Infants ≥27 weeks correc te d \ngestationl age were eligible for inclusion in this study.  \nBoth ce ntres routinely used locally-applied CHX-ba sed antiseptic s (0.015% – 2% CHX in 70%  \nisopropanolol) for pre-procedural skin disin fection be fore the insertion of indwelling catheters. \nIs olat e c ollec tion   \nAs part of a previou s surveillance study from this laboratory in December 2017 to March 2018[27], a  \npanel of ~800 CoNS were isolated from skin swabs taken at the NICU of the  Norfolk and Norwich \nUniversity Hospital (NNUH). Swabs were taken on admission and once week ly from each baby \nthroughout their NICU stay from various body site s including the ear, axilla, groin and rectum.   \nInfants admitted to the BRI NICU also had skin swabs taken on admission and then once weekly for \ntheir duration of stay, over a period of 8 weeks (between January and March 2020). All infants \nadmitted to the BRI NICU were eligible for inclusion, regardless of gestational age or expected \nduration of stay. A single charcoal swab (Amies Charcoal Transport Swab) was used to take a body  \nsweep, incorporating the ear, neck, an axilla, umbilical are a and groin. The swabbing was typically  \ncarried out 12-16 hours after wa shing occurred. Swabs were stored locally at 4 \no C.  Batches were  \nsecurely packaged and posted to the Quadram Institute Bioscience (QIB), Norw ich, every 3 weeks, \nwhere they were stored a t 4 \no C upon arrival.  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n7 \n \nA unique study ID was allotted to each infant enrolled using their anonymised code generated by the \nBadgerNet neonatal platform (CleverMed, UK). Birth weights, dates of admission and swabs, birth \ngestational age, gender of infant, birthing method, location of birth and  corrected gestational age  at \nenrolment wa s coll ected. No identifying data were transmitted out of the participating sites and \ncompleted anonymised data were collated at QIB into a ma ster database.  \nIs olati on o f  Co N S   \nCharcoal swabs were streaked on Columbia Blood Agar (CBA; Oxoid Thermo Fiser Scientific, USA), \ncandidate CoNS were then sub-cultured on Mannitol-Salt Agar (MS A; Oxoid Thermo Fiser Scientific , \nUSA). Isolates were tested for coagul ase (Coagulase Test Slides, Millipore,  Sigma), and any isolate s \nsuspected to be En teroc occ i  were grown on Bile Aesculin Agar (Oxoid Thermo Fise r Scientific , USA). \nFinally, catalase te sts were used with 20 % hydrogen peroxide. Isolates considered to be CoNS base d \non the phenotyping above we re saved and given a unique study number.  \nAnti mic r o bial su scepti bi lity te st ing  \nThe minimum inhibitory concentration (MIC) of OCT and CHX was determined for all isolate s \naccording to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines[28]. \nMuller Hinton (MH) Agar (Oxoid) was prepared with concentrations o f antiseptic s ranging from 0.25 \nµg/mL to 64 µg/mL. Overnight cultures grown in MH broth were diluted 1/10,000 and 1 µL drops \nwere plated on to the antiseptic containing MH Agar and incubated at 37 \no C for 24 hrs. Two control  \nstrains, TW20 and F77, were used throughout[29 ]. An MIC breakpoint of 4 µg/mL has bee n \nsuggested to de termine CHX resistanc e; no breakpoints have been proposed for OCT to date  \nalthough 2 µg /mL has been used previously a s an epidemiological cut off [30].  \nStati stics  \nData were analysed using GraphPad (PRISM 5). Correlation analysis used nonpa rametric Spea rman \ntests, one-tailed with confidence levels of 95 %. The nonparametric one-tailed T-Test and the Mann-\n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n8 \n \nWh i t n e y  te st  w e r e  us e d  to  i d en t if y s ig n ifi ca n t  d i ff e re n c es  b et we e n  M IC  d a ta  wi t h  a  9 5  %  c on f i d e n c e \nlevel.  \nEthic s \nThe study protocol was reviewed by the Research Services Manager of the Norfolk and Norwich \nUniversity Hospitals NHS Foundation Trust and was approved as a surveillanc e study that did not \nrequire a formal ethics committee review.  \n \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n9 \n \nResults \nIs olati on o f  Co N S  from Br ad ford neo n ate s \nA total of 56 infants from BRI were enrolled in the study. From these infants, 200 skin swabs were  \ntransported to QIB. These were made up of both admission swabs (n=30) and swabs taken weekly  \n(n=170). One swab was discarded due to inadequate labelling. Afte r swabs were incubated plates \ntypically demonstrated heavy growth of both Gram-p ositive and Gram-negative isolates \ndemonstrating various colony morphologies. This contra sts with the results in our previou s study \nfrom NNUH where individual swabs generally had a  smaller number of isolates with less mixed \ncultures. Of 180 Gram-positive isolates, a total of 78 were confirmed a s CoNS and retained for \nphenotypic testing. \nSusc epti bility  of Br ad for d CoNS is ola te s t o anti se ptic s \nThe MICs of CHX and OCT were  de te rmined for the isolates from BRI. Isolates were generally very  \nsensi tive to OCT and the MICs ranged betwee n ≤0.125-1 µg/mL with the majority (48.7%) of the  \nisolates (n= 38) being inhibited by ≤0.125 µg/mL. Two isolates had a MIC of 0.25 µg/mL, 32 isolates \n(41%) had a MIC of 0.5 µg /mL and the re maining 6 (7.7%) had a MIC of OCT of 1 µg/mL.  \nThe isolates were also tested against CHX. For 44.9 % of the isol ates (n=35) the MIC of CHX wa s \n≤0.125 µg/mL, for 29 (37.2% ) it was 0.25 µg/mL, 1 isola te had a CHX MIC of 0.5 µg/mL and the  \nremaining 12 (15.4 %) had a CHX MIC of 1 µg/mL. No isolates from BRI was above the proposed \nbreakpoints for eith er antiseptic. \nThe CHX and OCT MIC data for each of the Bradford isolates were compared against each other to \nd e t e r m i n e  w h e t h e r  t h e r e  w a s  a n y  r e l a t i o n s h i p  b e t w e e n  t h e  s u s c e p t i b i l i t y  t o  t h e  t w o  a g e n t s .  T h i s  \nanalysis (Figure 1) showed no direct relationship between susceptibility to the two antiseptics ( P = \n0.4), which is similar to our previous findings[29]. \nComp arati v e an ti sep tic  s u s c epti bility  o f is olate s fr o m Br ad ford an d Norwic h  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n10 \n \nAntiseptic susceptibility of the BRI isola tes from the daily OCT -washed babies was compared with \nthe panel of 863 CoNS isolated from babies in the NNUH NICU where infants are not routinely  \nbathed with OCT. A comparison in the susceptibility profile s of the population of CoNS from BRI and \nNNUH showed significantly decreased susceptibility in the NNUH population to both antiseptics \n(figures 2 and 3).  \nThe MICs of OCT for infants from NNUH ranged between 1 and 16 µg/mL (mean of 2.319 SEM±  \n0.078 µg/mL), compared with a narrower range of ≤ 0.125 and 1 µg/mL (mea n of 0.394 SEM± 0.029 \nµg/mL) for BRI isol ates (Figure 2a). There was a significant difference in the mean MIC for OCT  \nbetween Bradford and Norwich NICUs, ( P= <0.0001, Figure 2B).  \nThe MICs of CHX for NNUH isola tes ranged between 2 to 64 µg/mL (mean of 20.1 SEM± 0.5 µg/mL), \ncompared with a range of ≤ 0.125 to 1.0 µg/mL for isolates from babies at BRI (mean of 0.31 SEM±  \n0.04 µg/mL) (Figure 3). A clear difference  in the distribution of CHX susceptibili ty of the isolates from \nthe two sites can be observed. There was a significant difference between the mean MIC for CHX \nbetween the Br adfor d and N NUH  isolates ( P= <0.0001, Figure 3). In total 817 (94.7 %) isolates from \ninfants at the NNUH had a MIC for CHX greate r than 4 µg/mL whereas no isolates from Bradford \nNICU had a MIC of CHX >1 µg /mL. \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n11 \n \nDis c us sion  \nIn this study we sought to examine the prevalence and antiseptic susceptibility of CoNS from the skin \nof ne onates where washing with OCT is routine daily practice, and to compare the antiseptic  \nsusceptibility with a panel of isolate s from a unit which does not bathe infants routinely in the  \nperiod between admission and discharge. \nInoculation of swabs from BRI typically resulted in extensive bac terial growth made up of multiple \nmorphologically distinct bacteria, including a mixture of Gram-positive and Gram-negative bacteria . \nTherefore, despite being bathed regularl y using OCT, the numbers of organisms on the skin of babies \nfrom BRI remained high, and in fact more variation was se en than for swabs attained from the NNUH \nusing the same methodology, althoug h this is an anecdotal observation. T he skin swabbing \ntechnique in BRI involved carrying out a whole-body composite swab, which incorporated the ear, \nneck, axilla, umbilical area and groin. It has been suggested that there is not much differentiation \nbetween differing sites of the body and the skin burden, however this may have c ontributed towards \nthe high number of organisms recovere d, and in particular the greate r numbers of puta tive Gram-\nnegative bacteria [31]. Swabbing was carried out up to 16 hours after the wa shing of the infants \noccurred, sampling time was not standardised to fit with practice s on the ward , changes over time \nmay have been seen if a defined series of time points were assessed. Regardless of these caveats, it \nis clear tha t the OCT washing regime does not sterilise neonatal skin, or that the microbiota is \nquickly reinstated with multiple organisms soon after washing. Analy sis of infa nts for whom there  \nwas both an admission swab and a weekly swab showed a similar number of colonie s were picked \nfrom both plates - this would a rgue against acquisition of OCT-tolerant organisms after initial  \nadmission. \nA previous study showed that for CHX after an initial decrea se in the bacterial skin burden after \napplication, the number of recovered organisms increases and ba seline lev els are reached by \napproximately 72 hours [21 ].  CHX demonstrates a ‘substantive effect’, whereby the dried re sidue of \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n12 \n \nagent remains active in situ for a prolonged period post application onto the skin, which may reflect \nwhy a longer period is needed to repopulate the skin microbiota than after OCT exposure.  \nThe susceptibility data did not sugge st that repeated/frequent exposure to OCT selects for antiseptic  \ntolerance on skin i sola te s (Figure 2a and 3a). In fact, isolates from BRI were significantly more  \nsusceptible to both antiseptics than those from NNUH and all isolates with highest MICs were from \nNNUH. This is similar to our recent comparison of the NNUH panel with a German panel (who \nregularly use OCT based antiseptics for skin decolonization prior to catheter insertion) and again \nsuggests CHX exposure appea rs more likely to selec t for antiseptic tolerance than OCT[27]. The  \nsubstantive effect of CHX may result in long lasting low concentrations of CHX remaining on the skin \nwhich might provide an environment for selection of tolerant mutants. Alternatively, CHX is more  \ncommonly incorpora ted in environmental cleaning wipes and products than OCT which may also \nreflect a greater selec tive pressure for i solate s with decreased tolerance. \nStrengths and L imitat i ons \nThis is the first study to assess microbiological impacts from practising routine  washing of babies \nwith an antiseptic. This study also suggests daily OCT washing does not select for decre ased \nantiseptic susceptibility in CoNS and assessment of the bacterial burden of plates shows OCT  \nwashing has a limited impact on any reduction in skin microbiota.  \n However, limitations in the study mean that possible di fferences in the genoty pes of the \nstrains in circulation be tween the units were not assessed. The isolation periods between the sites \nwere not exactly contemporaneous although no significant changes in units’ practice s occurred in \nthe intervening period. Also a larg er number of isolates from NNUH were included which may skew \ncomparison s to some degree. \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n13 \n \nConc lus ion  \nIn summary, this two-site observational study shows that frequent whole-body skin washing with \nOCT compared to not routinely washing does not appear to result in a lasting reduction in numbers \nof organisms found on the skin but also does not appear to select for OCT tolerant organisms. \nIsolates from the NNUH were much less susceptible to antiseptics than the BRI isolates, suggesting  \nthat the bathing of neonates in the BRI NICU does not selec t for resistance. The data suggest that \ndifferent antiseptic regimes can have significantly different impacts on the microbiota in terms of \nboth compositi on and antiseptic susceptibility.  \nClinical tri als to systematically compare efficacy, safety and microbiological impacts of different \nantiseptic regimes in order to design evidence informed guidelines are lacking for this vulnerable  \npatient group. Further work on skin cleansing in preventing neona tal sepsis is vital in order to \nproduce best practice guideline s which will minimise infection and potential for selection of \nantiseptic re sistance. \n \n \n \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n14 \n \nReference s  \n1. 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(which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n16 \n \nFig ur e s   \nFig ur e  1: Susceptibility of isolates from BRI to OCT and CHX showed no correlation (p= 0.4, according  \nto Spearman test). \nFig ur e  2: A Comparison of MICs of OCT against isolates from BRI where regular daily whole-body  \nOCT washing was in place (n=78) and isolate s from NNUH where there wa s no regular washing of \nneona te s while in NICU (n=863). B Box plot showing numbers of isolates with different OCT MICs \nfrom each site (** ** P = <0.0001). Thin horizontal line indicates the mean and whiskers standard \nerror.  \nFig ur e  3: A Comparison of MICs of CHX against isolates BRI where regular da ily whole-body OCT  \nwashing was in place (n=78) and isolates from NNUH where there wa s no regular washing of \nneona te s while in NICU (n=863). B Box plot showing numbers of isol ates with different CHX MICs \nfrom each site (** ** P = <0.0001). Thin horizontal line indicates the mean and whiskers standard \nerror.  \n  \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\n \n17 \n \nAck nowledge ment s \nWe sinc erely thank all NNUH and BRI research and clinical nurses who helped with skin swa b \ncollection. We are gra te ful to Julie Dawson, Research Services Manager at NNUH for reviewing our \nst udy protocol. \n \nConflic t  of  int e r est  \nNone \n \nSourc e of Funding \nThis work was supported by an award from the Biotechnology and Biological Sciences Research \nCouncil (BB/T014644/1 ).  \n \n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\nOCT MIC\nmg/ml\n% isolates\n0.125 0.250 0.500 1.000 2.000 4.000 8.000 16.00032.00064.000\n0\n20\n40\n60\n80\nBradford\nNNUH\n OCT MIC\nmg/ml\nBradford\nNNUH\n0.0625\n0.125\n0.25\n0.5\n1\n2\n4\n8\n16\n32\n64\nA B\n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\nCHX MIC\nmg/ml\n% isolates\n0.125 0.250 0.500 1.000 2.000 4.000 8.000 16.00032.00064.000\n0\n20\n40\n60\nBradford\nNNUH\n CHX MIC\nmg/ml\nBradford\nNNUH\n0.03125\n0.125\n0.5\n2\n8\n32\n128\nA B\n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint \n\nOCT MIC\nmg/ml\nCHX MIC\nmg/ml\n0.0 0.5 1.0 1.5\n0.0\n0.5\n1.0\n1.5\n . CC-BY 4.0 International licenseIt is made available under a \n is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)\nThe copyright holder for this preprint this version posted June 25, 2022. ; https://doi.org/10.1101/2022.06.23.22276813doi: medRxiv preprint","source_license":"CC-BY-4.0","license_restricted":false}