TEST OF THE NOVAERUS AIR CLEANING SYSTEM IN THE DEPARTMENT OF CLINICAL MEDICINE.

Transcription

1 TEST OF THE NOVAERUS AIR CLEANING SYSTEM IN THE DEPARTMENT OF CLINICAL MEDICINE. Performed by he Laboraory of Infecion Hygiene, Deparmen of Clinical Microbiology, Danish Naional Hospial. Responsible: Chief Physician, Leif Percival Andersen. 1

2 NOVAERUS AIR CLEANING SYSTEM. The Novaerus air cleaning sysem is based on he plasma disinfecion echnique. An aggregae of ionising air molecules o reacive radicals is insered ino he device and has a srong animicrobial effec. These reacive radicals also affec oher molecules such as allergens and aroma molecules. Air is acively sucked ino he device and hrough he plasma aggregae, where microorganisms are killed and oher molecules are modified. Dus paricles can be so large ha when passing he plasma aggregae, he amoun of reacive radicals are so numerous ha ligh flashes are emied. As he device does no emi radiaion or chemical compounds i can be used in an inpaien deparmen while paiens are saying in he room. Design of projec. Two idenical deparmens (3131 and 3132) in he Nephrology Clinic were chosen for he invesigaion. Inervenions were performed in one of he deparmens (3132) where he Novaerus device was insalled. In one half of he conrol deparmens, 2 devices were insalled in each room (called ) and in he oher half, one device was insalled in each room (called ). Furhermore, 6 large devices were insalled in he hall area. However hese were dismanled during he invesigaion due o ligh flashes, probably due o exising dus paricles. The specific rooms included in he invesigaion can be seen in he ables included in he repor. In he oher deparmen (3131), no Novaerus devices were insalled and i served as he conrol (called ). The specific rooms included in he invesigaion can be seen in he ables included in he repor. Sample imes. Microbiology samples were aken prior o he insallaion of he Novaerus devices (1 s aken on 3 rd -4 h Mar 2014). Then he devices were insalled wihou being urned on for 14 days. Subsequenly he devices were urned on and afer having been on for 21 days samples were aken (2 nd 9 h Apr 2014). Then he devices were urned off once again for 21 days wih a new subsequen sampling (3 rd 30 h Apr 2014). The Novaerus devices were urned on again and afer 3 monhs addiional samples were aken (4 h 2 nd Sep 2014). To invesigae he 2

3 long-erm effec of he Novaerus devices hey remained urned on for a furher 2 1/2 monhs wih new subsequen sampling (5 h 17 h Nov 2014). Samples. Microbiology samples were aken and samples for allergens and aroma compounds were no. Samples for baceria and fungus were aken during each. A he 3 rd and 5 h here were also samples aken for respiraory rac viruses. An air sample in four rooms in each of he 3 unis (3131-0, , and ) was aemped, along wih an air sample in each of he 2 halls. The samples were aken wih an air sampler assimilaing 1 m 3 of air and deposiing baceria and fungus on a plae wih rypic soy agar (TSA), which was incubaed a 37 o C for 48 hours, and he number of colonies was read. Samples from impressions from windowsills and cabines in 4 rooms in each of he 3 unis (3131-0, and ) were aken wih rypic soy agar (TSA) impression plaes. These s are regarded as being represenaive of wha falls ou of he air, bu hey can also include human ouch. Samples in serum bouillon from beds and floors in 4 rooms in each of he 3 unis (3131-0, and ) were aken. The samples were aken from paien beds and in he offices from chairs and floors. The samples were grown for 24 hours and inoculaed wih he aim o verify small quaniies of poenially pahogenic baceria. 3 inoculaions were aken wih large inoculaion swabs from 3 places in he inervenion unis ( and ) and from 4 places in he conrol uni (3131-0). The swabs were placed in a virus ranspor medium inhibiing baceria growh. The samples were analysed for a panel of respiraory rac viruses including e.g. influenza virus, parainfluenza virus, rhinovirus, coronavirus ec. 3

4 Resuls. There is a relaively large variaion in he air s, boh from hall o hall and wihin he individual sample days (Figure 1a). I looks as if i is o a larger exen a measure of he curren aciviy in he deparmen raher han an effec of he Novaerus devices. Germ coun in he air, culured a 37 o C: Uni Room 1 s Office (62 ) (123 ) (68 ) Office (74 ) Hall (110 ) (53 ) (43 ) (48 ) (50 ) I (117 ) (134 ) (91 ) 2 nd 3 rd 4 h h Wihdrawn Wihdrawn Wihdrawn 124 (excessive growh) 255 (excessive growh) Wihdrawn Wihdrawn 89 4

5 kim/m3 23 rd Jan Hall (248 ) (excessive growh) (184 ) (excessive growh) When invesigaing he average values of he air s in he hree areas wih wo, one and zero devices, here is no significan difference in he hree areas (Figure 1b). Figure 1a Air s in 3131 and 3132 Måling 1 Måling 2 Måling 3 Måling 4 Måling Konor Konor Gang I Figure 1b. 5

6 Kim/m3 23 rd Jan Average values in rooms wih 1, 2 and 0 devices <måling 1> <måling 2> <måling 3> <måling 4> <måling 5> Trypic Soy Agar (TSA) impression plaes from he windowsills had on average a lower germ coun han he air s. They were compleely dominaed by he normal flora of skin, coagulase negaive saphylococci () (Table 1). Table 1. TSA impressions, windowsill: Uni Room 1 s 2 nd 3 rd 4 h 5 h K (34 ) Wihdrawn Wihdrawn (34 ) (3 ) K (7 ) Wihdrawn Wihdrawn Wihdrawn Wihdrawn Wihdrawn -G (24 ) (14 ) (9 )

7 (4 ) Wihdrawn -I (11 ) (34 ) Wihdrawn (10 ) Wihdrawn Wihdrawn (16 ) G Wihdrawn Wihdrawn Wihdrawn Wihdrawn Wihdrawn Figure 2a shows ha here is a large variaion in he s, boh from one day of sampling o he nex and wihin he individual sample days. I is of more ineres ha he values in rooms wih Novaerus devices are lower han in rooms wihou hem (Figure 2b). This may be caused by fewer baceria falling ou of he air over a longer period, which is no refleced by he air s which are snapsho s. Figure 2a. 7

8 Germ coun Germ coun 23 rd Jan Windowsill TSA impressions K K I Måling 1 Måling 2 Måling 3 Måling 4 Måling 5 Figure 2b. 120 Average of windowsill TSA impressions wih 1, 2 and 0 devices <Måling> 1 <Måling> 2 <Måling> 3 <Måling> 4 <Måling> 5 8

9 As for he Trypic Soy Agar (TSA) impression plaes, he impression plaes from he ops of he cabines also had a consisenly lower germ coun han he air s. Aside from being dominaed by normal flora of skin coagulase negaive saphylococci (), many Bacillus species were also found in hese samples (Table 2). Table 2. TSA impression, cabine: Uni Room 1 s 2 nd 3 rd 4 h 5 h K (11 ) Wihdrawn Wihdrawn (51 ) (2 ) K (14 ) Wihdrawn Wihdrawn Wihdrawn Wihdrawn Wihdrawn -G (62 ) (41 ) Excessive growh (68 ) Wihdrawn -I (58 ) (78 ) Wihdrawn (9 ) Wihdrawn 37 (2 ) G Wihdrawn Wihdrawn Wihdrawn Wihdrawn Wihdrawn Figure 3a shows ha here is a large variaion in he s, boh from one day of sampling o he nex and wihin he individual sample days. I is of more ineres ha he values in rooms wih Novaerus devices are lower han in rooms wihou devices (Figure 3b). In his case, his may also be caused by fewer baceria falling ou of he air over a 9

10 Germ coun 23 rd Jan 2015 longer period, which is no refleced by he air s. However, his does no explain why he values are higher wih one han wih wo devices. Figure 3a. 180 TSA impressions on cabines Måling 1 Måling 2 Måling 3 Måling 4 Måling K K I Figure 3b. 10

11 Germ coun 23 rd Jan Average of TSA impressions on cabines wih 0, 1 and 2 devices Måling 1 Måling 2 Måling 3 Måling 4 Måling 5 Growh of incubaions in serum bouillon was carried ou in order o find possible poenially pahogenic baceria in he environmen, as i is a more sensiive mehod han he TSA impression plaes. Poenially pahogenic baceria were idenified wih MALDI-TOF. The samples were aken from paien beds and from chairs in offices (Table 3). Also growh samples were aken from he floors (Table 4). In boh ables, poenially pahogenic baceria are marked in red. = coagulase negaive saphylococci (normal flora of skin). = Bacillus species (ofen found in dus) = Bacillis cereus (ofen found in dus). A subsanial par of he samples are wihdrawn. No samples were aken on he firs day of. The oher days wihou sampling were due o he fac ha isolaion paiens were in he room hus prevening sampling. There was poenially pahogenic baceria in 4 of he samples from he area wih one Novaerus device and in 9 samples where 2 devices were presen in he room whereas here were only 6 samples wih poenially pahogenic baceria when no device was presen (Table 3). There was pahogenic baceria in 5 of he samples from he floor in he area wih one Novaerus device and in 3 samples wih 2 devices in he room, whereas 6 samples wih poenially pahogenic baceria were idenified where no device was insalled (Table 4). 11

12 Boh in samples from he beds and he floors, here was an increased number of samples wih poenially pahogenic baceria he furher he invesigaion progressed. The devices do no have an effec of he number of poenial pahogenic baceria, and he resuls are probably more a reflecion of saff conduc. Table 3. Growh: Bed/chair. Uni Room 1 s K Wihdrawn Wihdrawn 2 nd Ps. lueola 3 rd Wihdrawn Wihdrawn -K 4 h Wihdrawn 5 h Wihdrawn Panoea Wihdrawn -G Panoea Wihdrawn Lacobacillus Wihdrawn E. coli Wihdrawn K. oxioca Wihdrawn E. cloacae 12

13 I Wihdrawn K. pneumo Wihdrawn S. aureus Wihdrawn Wihdrawn G E. cloacae Wihdrawn S. aureus Enerobacer Wihdrawn A. baumanni Wihdrawn Wihdrawn C. freundii Table 4. Growh, floor: Uni Room 1 s nd Wihdrawn K Wihdrawn 3 rd A. baumanni Wihdrawn Wihdrawn -K G Wihdrawn 4 h Wihdrawn Wihdrawn Wihdrawn S. aureus Acineobacer Srepococcu s Wihdrawn 13

14 13383 Wihdrawn Wihdrawn Wihdrawn -I Wihdrawn Ps.sp. S. aureus Coryne Wihdrawn Wihdrawn G Wihdrawn Panoea sp. Srepococcu s S. aureus A. baumanni Leclercia Wihdrawn Corynefor m Wihdrawn Wihdrawn C. freundii Virus invesigaions. 3 virus samples were aken in rooms wih 1 Novaerus device and 3 virus samples from rooms wih 2 devices and 4 virus samples from rooms wihou devices a he 3 rd (21 days afer he device was urned off afer having been on for 14 days) and he 5 h (he devices have been urned on for 5 1/2 monhs). No virus was found in any of he 20 samples analysed for several respiraory rac viruses. The conrol deparmen 3131 can be regarded as he baseline for he virus load in a nephrology uni. As no posiive virus samples were found here, i would no be expeced o find any virus in he conrol deparmen Effecs on findings of baceria in paiens. Posiive microbiological samples from May o Ocober 2013 (he year prior o he Novaerus invesigaion) were compared wih posiive microbiology samples from May o Ocober 2014 (while he Novaerus invesigaion was carried ou). Samples from surface localiies, airways (expecoraes), incubaions from incisions sies, oher incubaions and urine were chosen as indicaors. In Table 5 he number of paiens wih posiive microbiological samples is saed. 14

15 In he conrol deparmen 3131, he number of paiens wih posiive microbiology indicaor baceria increased by 35% from 2013 o 2014, whereas he number of paiens wih posiive microbiological indicaor baceria reduced by 23% in he deparmen wih inervenion Tha sums up o a difference of more han 50% in he wo deparmens. I has no been aken ino consideraion wheher more or less samples were aken in he wo deparmens during he wo periods. The difference is so large ha his alone canno mos likely explain he resuling difference. The findings of baceria in he urine samples especially consiue he difference beween he conrol deparmen and he deparmen wih inervenion. Table 5. Sample ypes Expecoraes Incubaions, incision sie Oher incubaions Urine Toal Difference + 35% - 23% Conclusion. The effec of he Novaerus devices canno be measured as a snapsho of he curren bacerial load in he air wih air samples. However i looks as if here is a cerain reducion in he bacerial load which had fallen ono surfaces such as windowsills and on op of cabines. The laer are surfaces which are no ouched oo frequenly and where he occurrence of baceria is primarily due o fallou from he air raher han from human ouch. The reducion in bacerial load is however approximaely he same in windowsills and on cabines. However, i doesn' appear as if here is any difference in using one or wo Novaerus devices in he rooms. As here is no virus in he conrol deparmen or in he deparmen wih inervenion he effec of Novaerus devices on viruses has no been clarified in his invesigaion. This will require a new sudy focusing on viruses in deparmens where he occurrence has been clarified prior o he sar of he invesigaion. When he number of paiens wih posiive microbiology samples from surface localiies is examined, a reducion of abou 50% is seen in he deparmen wih inervenion, where he Novaerus devices have been insalled, compared o he conrol deparmen. This 15

16 difference is caused by urine samples conaining baceria. Why he difference is only observed in urine samples and no in oher superficial samples may be a coincidence jus as i has no been aken ino accoun wheher here were a larger or smaller number of samples in he invesigaed periods. The resuls show ha he Novaerus device may be effecive wih boh airborne baceria which had fallen ono surfaces and on he occurrence of posiive microbiological samples. I would be ineresing o coninue he invesigaion, especially wih regard o he effec on viruses and addiionally he effec on airway sympoms in paiens and saff. 16