c consult author(s) regarding copyright matters · 5 ballard6, timothy j kidd1,7, graham r...
TRANSCRIPT
This may be the author’s version of a work that was submitted/acceptedfor publication in the following source:
Stockwell, Rebecca, Wood, Michelle, He, Congrong, Sherrard, Laura, Bal-lard, Emma, Kidd, Timothy, Johnson, Graham, Knibbs, Luke, Morawska,Lidia, & Bell, Scott(2018)Face masks reduce the release of pseudomonas aeruginosa coughaerosols when worn for clinically relevant periods (Correspondence).American Journal of Respiratory and Critical Care Medicine, 198(10), pp.1339-1342.
This file was downloaded from: https://eprints.qut.edu.au/123202/
c© Consult author(s) regarding copyright matters
This work is covered by copyright. Unless the document is being made available under aCreative Commons Licence, you must assume that re-use is limited to personal use andthat permission from the copyright owner must be obtained for all other uses. If the docu-ment is available under a Creative Commons License (or other specified license) then referto the Licence for details of permitted re-use. It is a condition of access that users recog-nise and abide by the legal requirements associated with these rights. If you believe thatthis work infringes copyright please provide details by email to [email protected]
Notice: Please note that this document may not be the Version of Record(i.e. published version) of the work. Author manuscript versions (as Sub-mitted for peer review or as Accepted for publication after peer review) canbe identified by an absence of publisher branding and/or typeset appear-ance. If there is any doubt, please refer to the published source.
https://doi.org/10.1164/rccm.201805-0823LE
For Review Only
1
Face masks reduce the release of Pseudomonas aeruginosa cough aerosols when worn for 1
clinically-relevant time periods 2
3
Rebecca E Stockwell1,2
, Michelle E Wood1,2,3
, Congrong He4, Laura J Sherrard
5, Emma L 4
Ballard6, Timothy J Kidd
1,7, Graham R Johnson
4, Luke D Knibbs
8, Lidia Morawska
4, Scott C 5
Bell*1,2,3
; CF Cough Aerosol Group. 6
7
CF cough aerosol group members: 8
Maureen Peasey, Christine Duplancic, Kay A Ramsay, Nassib Jabbour, Peter O’Rourke, 9
Claire E Wainwright, Peter D Sly 10
11
1Lung Bacteria Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, 12
Herston QLD 4006, Australia 13
2Faculty of Medicine, The University of Queensland, Herston QLD 4006, Australia 14
3Adult Cystic Fibrosis Centre, The Prince Charles Hospital, 627 Rode Road, Chermside, QLD 15
4032, Australia 16
4International Laboratory for Air Quality and Health, Queensland University of Technology, 17
Brisbane QLD 4000, Australia 18
5Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom 19
6Statistical Support Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, 20
Herston QLD 4006, Australia 21
7School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia 22
QLD 4067, Australia 23
8School of Public Health, The University of Queensland, Herston QLD 4006, Australia 24
25
Page 1 of 34
For Review Only
2
Email: 26
37
*Corresponding author. Lung Bacteria Group, QIMR Berghofer Medical Research Institute, 38
300 Herston Road, Herston, Brisbane QLD 4006, Australia. 39
Tel: +61 7 3139 4770; Email: [email protected] 40
41
Author contributions: G.R.J., L.D.K., T.J.K., R.E.S., L.J.S., L.M. and S.C.B. conceived and 42
designed the experiment. S.C.B., T.J.K. and L.M. led the funding applications with other 43
members of the CF cough aerosol group (C.E.W and P.D.S.). M.E.W. and S.C.B. recruited 44
the study participants. R.E.S. and C.H. conducted the cough studies. G.R.J. acquired the 45
aerosol data. R.E.S. performed microbiological analysis. E.L.B. led the data analysis. R.E.S. 46
and S.C.B. provide overall responsibility for the data and wrote the manuscript, with input 47
from all co-authors. M.P., C.D., K.A.R., N.J., P.O., C.E.W and P.D.S. provided support to the 48
study including analysis and/or microbiology expertise and/or clinical supervision. 49
50
Page 2 of 34
For Review Only
3
Funding support: The project was funded by Cystic Fibrosis Foundation Therapeutics USA 51
(BELL14AO). T.J.K. acknowledges National Health and Medical Research Council 52
(NHMRC) Early Career (GNT10884488) and ERS-EU RESPIRE2 Marie Sklodowska-Curie 53
Postdoctoral Research (#4571-2013) Fellowship support. L.D.K. acknowledges an NHMRC 54
Early Career Fellowship (APP1036620). R.E.S acknowledges The Prince Charles Hospital 55
Foundation and Advance Queensland PhD Scholarships. 56
57
List ONE descriptor number that best classifies the subject of your manuscript: 9.17 58
Cystic Fibrosis: Translational & Clinical Studies 59
Total word count for the body of the manuscript = 1620 60
61
Page 3 of 34
For Review Only
4
Abstract 62
Introduction: The cystic fibrosis (CF) infection control guidelines recommend that people 63
with CF wear face-masks when in communal areas of hospitals. Recently, we reported short-64
term wear of face-masks (~10-minutes) reduced the release of Pseudomonas aeruginosa 65
aerosols during coughing. However, there is limited evidence to determine if face-masks 66
continue to be effective at reducing the release of infectious cough aerosols after longer wear 67
times. Methods: We recruited 25 people with CF and chronic P. aeruginosa infection and 10 68
healthy volunteers. All participants underwent up to 5 cough tests in a validated cough rig: 1) 69
uncovered cough; 2) coughing with surgical mask worn for 10-minutes; 3) coughing with 70
surgical mask worn for 20-minutes; 4) coughing with a surgical mask worn for 40-minutes; 5) 71
coughing with an N95 respirator worn for 20-minutes (optional). The wear time of the mask 72
included a 5-minute cough period in the aerosol collection rig. Sputum samples and cough 73
aerosols were collected from participants with CF as previously described. All participants 74
rated their level of comfort post-test. Results: Surgical masks and N95 respirators were 75
effective at reducing the release of P. aeruginosa aerosols during coughing after 40-minutes 76
total wear and 20-minutes total wear respectively. Both participants with CF and healthy 77
volunteers rated the surgical masks as more comfortable compared to N95 respirators. 78
Conclusions: Surgical masks were the preferred interface to wear as source control and were 79
effective at reducing the release of P. aeruginosa aerosols during coughing after 40-minutes 80
of total wear. 81
Page 4 of 34
For Review Only
5
Introduction 82
Aerosol dissemination of respiratory pathogens may contribute to person-to-person 83
transmission in people with cystic fibrosis (CF) [1]. This evolving knowledge of transmission 84
modes has led to an update of the CF Foundation Infection and Prevention Control Guidelines 85
recommending people with CF wear surgical masks in communal hospital areas to prevent the 86
spread of CF respiratory pathogens [2]. These guidelines recommended the use of surgical 87
masks as source control despite limited evidence for this application. 88
89
We recently demonstrated that short-term wear of face-masks (10-minutes total wear) 90
significantly reduces the release of Pseudomonas aeruginosa aerosols during coughing in 91
people with CF [3]. These findings are consistent with an earlier study of people with CF that 92
reached the same conclusion after very short-term wear of surgical masks (worn for 21 93
coughs) [4]. These results and a recent editorial to our short-term mask wear study [5] support 94
our current aim to investigate the effectiveness, tolerability and functionality of face-masks as 95
source control after extended wear. 96
97
Methods 98
We recruited 25 people with CF and chronic P. aeruginosa infection [6] from the Adult 99
Cystic Fibrosis Centre, The Prince Charles Hospital, Brisbane, Australia. Ten healthy 100
volunteers were recruited from hospital and research staff to assess mask comfort and mask 101
weight change. All participants performed up to five randomly ordered tests in a validated 102
cough system [7]: 1) uncovered cough; 2) coughing with surgical mask worn for 10-minutes); 103
3) coughing with surgical mask worn for 20-minutes; 4) coughing with surgical mask worn 104
for 40-minutes; 5) coughing with N95 mask worn for 20-minutes [3, 7]. The N95 test was an 105
optional test based on the poor comfort ratings observed in our earlier mask study [3]. 106
Page 5 of 34
For Review Only
6
107
The duration of the mask wear tests were selected based on observation of patients moving 108
around communal areas of the hospital described here. Two types of masks were tested: 109
“surgical mask” [Catalogue # 47107; Halyard FLUIDSHIELD Level 3 Fog-Free Procedure 110
Mask (∆P<2.5), Georgia, USA] and “N95 mask” [Catalogue # 46827 (small) or 46727 111
(regular), Halyard FLUIDSHIELD N95 Particulate Filter Respirator and Surgical Mask, 112
Georgia, USA]. New masks were used for each test. Whilst wearing the mask, participants 113
were free to move around the study room (including able to talk and cough spontaneously) 114
until they performed the voluntary cough in the aerosol collection rig. The total wear time of 115
the masks included 1-minute positioning of the participant into the rig, 2-minutes of tidal 116
breathing with HEPA-filtered air, a 5-minute cough period, followed by another 2-minutes of 117
tidal breathing. Cough aerosol collection, sputum processing and P. aeruginosa genotyping 118
were performed as previously described [1, 3, 8]. All participants rated their comfort levels 119
after each test [3, 9]. All masks were weighed before and following each test. 120
121
SPSS version 25 was used for statistical analysis. Participants with CF were stratified by the 122
amount of aerosol colony forming units (CFU) produced during the uncovered cough test: 123
high producer (total CFU was ≥10) or no/low producer (total CFU was <10) [3]. Categorical 124
variables were examined using Pearson Chi-squared test or Fisher’s Exact test. Continuous 125
variables were examined using a Student t-test or Mann-Whitney U test. CFU were log 126
transformed and the paired t-test examined changes over time. The McNemar-Bowker test 127
was used to examine comfort scores over time. The Wilcoxon Signed Rank Test was used to 128
examine the change in mask weight over time. 129
130
Results 131
Page 6 of 34
For Review Only
7
Microbiology results are provided in Table 1. P. aeruginosa was cultured from the sputum of 132
25/25 participants with CF and was cultured in cough aerosols during the uncovered cough 133
test of 20/25 participants. P. aeruginosa was cultured from cough aerosols of 9/20 134
participants during any of the surgical mask tests (10-minutes, 20-minutes and 40-minutes 135
total wear time) and 4/20 participants during the N95 mask test of 20-minutes total wear. The 136
CFU were significantly reduced for the surgical mask tests compared with the uncovered 137
cough test (p<0.001). Between mask tests, the CFU count remained similar as the duration of 138
surgical mask wear increased (compared to 10-minute total wear: 20-minute total wear, 139
p=0.99; 40-minute total wear, p=0.56) as well as between mask types (surgical mask worn for 140
20-minutes total versus N95 mask worn for 20-minutes total, p=0.19). The P. aeruginosa 141
strain types found in the cough aerosols were genetically indistinguishable from the paired 142
sputum sample of each participant. 143
144
Participants with CF rated surgical masks less comfortable than healthy volunteers for all test 145
durations (surgical mask: 10-minutes, p=0.001; 20-minutes, p=0.007; 40-minutes, p=0.023; 146
N95: 20-minutes, p=0.018) (Table 2). Of the participants with CF, 23/25 (92%) rated comfort 147
as good during the uncovered cough test, whereas 8/25 (32%) rated the 40-minutes surgical 148
mask test as good comfort and 4/25 (16%) rated the N95 mask test as good comfort (Table 2). 149
Participants with CF were more tolerant of mask wear (good comfort) after 10- and 20-150
minutes total wear time if they had higher lung function, yet this difference was lost after 40-151
minutes of surgical mask wear. For the healthy participants, 9/10 (90%) rated the uncovered 152
cough test as good and 8/10 (80%) rated the 40-minutes surgical mask test as good comfort 153
whereas only 2/10 (20%) rated comfort as good for the N95 mask (Table 2). 154
155
Page 7 of 34
For Review Only
8
The change in mask weight for each test ranged from no weight change to a maximum weight 156
change of 0.02g. This change in mask weight was comparable between participants with CF 157
and healthy volunteers (surgical mask: 10-minutes, p=0.054; 20-minutes, p=0.050; 40-158
minutes, p=0.12). Similarly, when the change is mask weights for each test were compared 159
there was no statistical difference: between surgical mask tests (10-minutes versus 20-160
minutes, p=0.73; 20-minutes versus 40-minutes, p=0.25) and between mask types (20-161
minutes: surgical mask versus N95 mask, p=0.21) (Table 2). There was a minor increase in 162
surgical mask weight (median change, 0.01g) after 40-minutes compared with 10-minutes 163
wear (p=0.031) (Table 2). 164
165
Discussion 166
Our study demonstrates that face masks worn for clinically-relevant time periods are effective 167
at reducing the release of potentially infectious aerosols during coughing in people with CF. 168
These results extend upon our earlier observations that demonstrated surgical masks and N95 169
masks were both effective at reducing the release of infectious cough aerosols when the 170
duration of mask wear was shorter [3]. Therefore, the outcomes of our earlier mask study and 171
the current study demonstrate that surgical masks are effective and tolerable as source control. 172
These studies support the CF Foundation (USA) recommendations regarding the use of 173
surgical masks to interrupt the dispersal of viable aerosols in the hospital setting [2]. 174
175
Surgical masks were the preferred mask type for source control in terms of comfort, which is 176
similar to our recent study [3]. In contrast, the N95 mask was rated uncomfortable by ~50% 177
of our participants with CF and this was also similar to what was reported in our earlier mask 178
study where ~60% of participants with CF rated the N95 mask comfort as poor [3]. In 179
comparison, the surgical mask comfort was rated as good/acceptable comfort when worn for 180
Page 8 of 34
For Review Only
9
10-minutes [3]. The healthy volunteers tolerated the surgical masks better than the 181
participants with CF and within the participants with CF, those with higher lung function 182
tolerated surgical masks better also. Furthermore, when the comfort of surgical masks was 183
assessed after extended wear in this cohort, a major finding was that the comfort ratings 184
remained unchanged regardless of wear time for both people with and without CF. Therefore, 185
surgical masks are not only effective but are also well tolerated with participants rating them 186
as of sufficient or good comfort after 40-minutes total wear. 187
188
An accompanying editorial of our recent mask study [3] questioned if mask dampness may 189
affect the ability of the mask to function as source control after prolonged wear times [5]. The 190
CF infection control guidelines indicate that masks being used as source control should be 191
replaced when damp [2] and excessive moisture accumulation was a common reason for 192
surgical mask replacement in people with tuberculosis using surgical masks as source control 193
[10]. Our data indicates that although there was evidence of surgical mask moisture 194
accumulation after 40-minutes total wear (estimated by increased weight), the surgical mask 195
continued to function effectively as source control mitigating this concern. 196
197
There are several limitations to this study: 1) The infectious dose of P. aeruginosa is 198
unknown and therefore the infection risk cannot be determined; 2) Participants remained in 199
view of staff while wearing the masks and this may have modified the extent to which 200
participants interfered with the mask leading to an incorrect estimation on the masks 201
protective effects; 3) Participants were seated during the cough testing and this may have 202
impacted on the ability of the participant to cough freely during the testing; 4) The number of 203
coughs were counted for each test. While some participants did experience episodes of 204
spontaneous cough during testing, this was not recorded separately as differentiating between 205
Page 9 of 34
For Review Only
10
spontaneous and voluntary cough would be an arbitrary ‘call’. Therefore, the effects of 206
spontaneous cough on aerosol dispersion is unknown and furthermore, the estimation of the 207
protective effects of the face masks may be inaccurate; 5) The effectiveness and tolerability of 208
masks is reported in adults only and thus, these characteristics need to be studied in children; 209
6) Our study had a maximum total wear time of 40-minutes and the effectiveness of masks 210
worn for longer periods is unknown; 7) The inwards protection of the masks was not tested in 211
our study and has been reported in a recent systematic review as an under-studied area [11]. 212
To undertake such studies would not be considered ethical. 213
214
Our study confirms the effectiveness of surgical masks at reducing the release of P. 215
aeruginosa cough aerosols in people with CF and provides evidence of patient tolerability and 216
functionality of these masks as source control after 40-minutes of total wear. 217
218
Acknowledgements: We thank Dr Farhad Salimi for his aerosol support to the study. We 219
thank Greg Flohr and staff from the Central Pathology Laboratory (Royal Brisbane and 220
Women’s Hospital), Pathology Queensland for microbiological support to the study. We 221
thank the Adult CF Centre team in supporting recruitment to the studies. We also thank all the 222
participants in the study for supporting the work. 223
224
Page 10 of 34
For Review Only
11
Table 1: Demographic and clinical characteristics of the study participants 225
Group Production level in CF participants
Healthy CF p-value
No/low (<10 CFU)
High (≥ 10 CFU)
p-value
(n = 10) (n = 25)
(n = 14) (n = 11)
Participant characteristics
Age, years, mean (SD) 37.3 (12.3) 33.3 (9.0) 0.29 36.7 (9.3) 28.9 (6.9) 0.029
Sex, male, n (%) 6 (60.0) 15 (60.0) 1.00 9 (64.3) 6 (54.5) 0.70
Body mass index (BMI), kg/m2, mean (SD) 24.6 (3.5) 22.8 (3.2) 0.14 22.5 (3.7) 23.1 (2.6) 0.63
FEV1 % predicted, mean (SD) 92.6 (9.2) 53.8 (20.8) <0.001 54.2 (23.2) 53.3 (18.2) 0.91
Mean P. aeruginosa sputum concentration, x 107 CFU/mL (95% CI)
a n/a
5.2 (2.1 –
12.9) - 1.9 (0.7 – 5.7) 18.3 (4.7 – 70.9) 0.008
Participants with P. aeruginosa detected in cough aerosols
Uncovered cough test
n (%) n/a 20 (80.0) - 9 (64.3) 11 (100.0)
Mean CFU (95% CI)a
17 (7 - 43)
2 (1 – 4) 75 (34 – 165) <0.001d
Surgical mask tests
10-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
4 (1 – 10)
1 5 (1 – 13)
20-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
4 (1 – 10)
1 4 (1 – 11) 0.99
e
40-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
1 4 (1 – 9) 0.56f, 0.64g
N95 mask test~
20-minutes total wear (n=23)
3 (1 – 7)
n (%) n/a 4 (17.4) - 0 (0.0)b 4 (40.0)c
Mean CFU (95% CI)a
2 (0 – 6)
n/a 2 (0 – 6) 0.19
h
Page 11 of 34
For Review Only
12
Definitions: FEV1, forced expiratory volume in 1 second; CFU, colony forming unit; CFU/mL, CFU per millilitre of sputum; SD, standard deviation; 226
CI, confidence interval, n/a, not applicable ~ Optional test 227
228 ageometric mean 229
bparticipant number (n) = 13 230
cparticipant number (n) = 10 231
dUncovered cough (geometric mean CFU) compared to each surgical mask test (geometric mean CFU) 232
eSurgical masks (geometric mean CFU): 10-minutes versus 20-minutes total wear 233
fSurgical masks (geometric mean CFU): 10-minutes versus 40-minutes total wear 234
gSurgical masks (geometric mean CFU): 20-minutes versus 40-minutes total wear 235
hMean CFU surgical mask 20-minutes total wear versus mean CFU N95 mask 20-minutes total wear 236
Page 12 of 34
For Review Only
13
Table 2: Summary of mask properties 237
Mask comfort Mask weight change
Mask properties Healthy
n (%)
CF
n (%) p-value
All participants
Median (IQR)
p-value
Uncovered cough comfort level 1.00 n/a n/a
Poor 0 (0.0 %) 0 (0.0 %)
Sufficient 1 (10.0 %) 2 (8.0 %)
Good 9 (90.0 %) 23 (92.0 %)
Coughing wearing a surgical mask – 10-minutes total wear 0.001 0.01g (0.00g – 0.02g) n/a
Poor 1 (10.0 %) 0 (0.0 %)
Sufficient 0 (0.0 %) 15 (60.0 %)
Good 9 (90.0 %) 10 (40.0 %)
Coughing wearing a surgical mask – 20-minutes total wear 0.007 0.01g (0.00g – 0.02g) 0.73a
Poor 1 (10.0 %) 1 (4.0 %)
Sufficient 0 (0.0 %) 13 (52.0 %)
Good 9 (90.0 %) 11 (44.0 %)
Coughing wearing a surgical mask – 40-minutes total wear 0.023 0.02g (0.01g – 0.03g) 0.25b, 0.031
c
Poor 1 (10.0 %) 2 (8.0 %)
Sufficient 1 (10.0 %) 15 (60.0 %)
Good 8 (80.0 %) 8 (32.0 %)
Coughing wearing N95 mask -20-minutes total wear 0.018 0.02g (0.00g – 0.04g) 0.21d
Poor 0 (0.0 %) 11 (47.8 %)
Sufficient 7 (77.8 %) 8 (34.8 %)
Good 2 (22.2 %) 4 (17.4 %)
238 aSurgical mask weight change: 10-minutes versus 20-minutes total wear 239
bSurgical mask weight change: 20-minutes versus 40-minutes total wear 240
cSurgical mask weight change: 10-minutes versus 40-minutes total wear 241
dMask weight change after 20-minutes wear: surgical mask versus N95 mask 242
Page 13 of 34
For Review Only
14
References: 243
1. Knibbs, L.D., Johnson, G.R., Kidd, T.J., Cheney, J., Grimwood, K., Kattenbelt, J.A., 244
O'Rourke, P.K., Ramsay, K.A., Sly, P.D., Wainwright, C.E., Wood, M.E., Morawska, 245
L., and Bell, S.C. Viability of Pseudomonas aeruginosa in cough aerosols generated by 246
persons with cystic fibrosis. Thorax. 2014;69(8):740-5 247
2. Saiman, L., Siegel, J.D., LiPuma, J.J., Brown, R.F., Bryson, E.A., Chambers, M.J., 248
Downer, V.S., Fliege, J., Hazle, L.A., Jain, M., Marshall, B.C., O'Malley, C., Pattee, 249
S.R., Potter-Bynoe, G., Reid, S., Robinson, K.A., Sabadosa, K.A., Schmidt, H.J., Tullis, 250
E., Webber, J., and Weber, D.J. Infection prevention and control guideline for cystic 251
fibrosis: 2013 update. Infect Control Hosp Epidemiol. 2014;35 Suppl 1:S1-s67 252
3. Wood, M.E., Stockwell, R.E., Johnson, G.R., Ramsay, K.A., Sherrard, L.J., Jabbour, N., 253
Ballard, E., O'Rourke, P., Kidd, T.J., Wainwright, C.E., Knibbs, L.D., Sly, P.D., 254
Morawska, L., and Bell, S.C. Face Masks and Cough Etiquette Reduce the Cough 255
Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis. Am 256
J Respir Crit Care Med. 2018;197(3):348-355 257
4. Driessche, K.V., Hens, N., Tilley, P., Quon, B.S., Chilvers, M.A., de Groot, R., Cotton, 258
M.F., Marais, B.J., Speert, D.P., and Zlosnik, J.E. Surgical masks reduce airborne 259
spread of Pseudomonas aeruginosa in colonized patients with cystic fibrosis. Am J 260
Respir Crit Care Med. 2015;192(7):897-9 261
5. Simmonds, N.J. and Bush, A. The Man in the Paper Mask: One (Mask) for All and All 262
for . . . Cystic Fibrosis? Am J Respir Crit Care Med. 2018;197(3):281-283 263
6. Ramsay, K.A., Sandhu, H., Geake, J.B., Ballard, E., O'Rourke, P., Wainwright, C.E., 264
Reid, D.W., Kidd, T.J., and Bell, S.C. The changing prevalence of pulmonary infection 265
in adults with cystic fibrosis: A longitudinal analysis. J Cyst Fibros. 2017;16(1):70-77 266
Page 14 of 34
For Review Only
15
7. Johnson, G.R., Knibbs, L.D., Kidd, T.J., Wainwright, C.E., Wood, M.E., Ramsay, K.A., 267
Bell, S.C., and Morawska, L. A Novel Method and Its Application to Measuring 268
Pathogen Decay in Bioaerosols from Patients with Respiratory Disease. PLoS One. 269
2016;11(7):e0158763 270
8. Syrmis, M.W., Kidd, T.J., Moser, R.J., Ramsay, K.A., Gibson, K.M., Anuj, S., Bell, 271
S.C., Wainwright, C.E., Grimwood, K., Nissen, M., Sloots, T.P., and Whiley, D.M. A 272
comparison of two informative SNP-based strategies for typing Pseudomonas 273
aeruginosa isolates from patients with cystic fibrosis. BMC Infect Dis. 2014;14:307 274
9. Gregoretti, C., Confalonieri, M., Navalesi, P., Squadrone, V., Frigerio, P., Beltrame, F., 275
Carbone, G., Conti, G., Gamna, F., Nava, S., Calderini, E., Skrobik, Y., and Antonelli, 276
M. Evaluation of patient skin breakdown and comfort with a new face mask for non-277
invasive ventilation: a multi-center study. Intensive Care Med. 2002;28(3):278-84 278
10. Dharmadhikari, A.S., Mphahlele, M., Stoltz, A., Venter, K., Mathebula, R., Masotla, T., 279
Lubbe, W., Pagano, M., First, M., Jensen, P.A., van der Walt, M., and Nardell, E.A. 280
Surgical face masks worn by patients with multidrug-resistant tuberculosis: impact on 281
infectivity of air on a hospital ward. Am J Respir Crit Care Med. 2012;185(10):1104-9 282
11. MacIntyre, C.R., and Chughtai, A.A. Facemasks for the prevention of infection in 283
healthcare and community settings. BMJ. 2015;350:h694 284
Page 15 of 34
For Review Only
1
Face masks reduce the release of Pseudomonas aeruginosa cough aerosols when worn for 1
clinically-relevant time periods 2
3
Rebecca E Stockwell1,2, Michelle E Wood1,2,3, Congrong He4, Laura J Sherrard5, Emma L 4
Ballard6, Timothy J Kidd
1,7, Graham R Johnson
4, Luke D Knibbs
8, Lidia Morawska
4, Scott C 5
Bell*1,2,3; CF Cough Aerosol Group. 6
7
CF cough aerosol group members: 8
Maureen Peasey, Christine Duplancic, Kay A Ramsay, Nassib Jabbour, Peter O’Rourke, 9
Claire E Wainwright, Peter D Sly 10
11
1Lung Bacteria Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, 12
Herston QLD 4006, Australia 13
2Faculty of Medicine, The University of Queensland, Herston QLD 4006, Australia 14
3Adult Cystic Fibrosis Centre, The Prince Charles Hospital, 627 Rode Road, Chermside, QLD 15
4032, Australia 16
4International Laboratory for Air Quality and Health, Queensland University of Technology, 17
Brisbane QLD 4000, Australia 18
5Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom 19
6Statistical Support Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, 20
Herston QLD 4006, Australia 21
7School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia 22
QLD 4067, Australia 23
8School of Public Health, The University of Queensland, Herston QLD 4006, Australia 24
25
Page 16 of 34
For Review Only
2
Email: 26
37
*Corresponding author. Lung Bacteria Group, QIMR Berghofer Medical Research Institute, 38
300 Herston Road, Herston, Brisbane QLD 4006, Australia. 39
Tel: +61 7 3139 4770; Email: [email protected] 40
41
Author contributions: G.R.J., L.D.K., T.J.K., R.E.S., L.J.S., L.M. and S.C.B. conceived and 42
designed the experiment. S.C.B., T.J.K. and L.M. led the funding applications with other 43
members of the CF cough aerosol group (C.E.W and P.D.S.). M.E.W. and S.C.B. recruited 44
the study participants. R.E.S. and C.H. conducted the cough studies. G.R.J. acquired the 45
aerosol data. R.E.S. performed microbiological analysis. E.L.B. led the data analysis. R.E.S. 46
and S.C.B. provide overall responsibility for the data and wrote the manuscript, with input 47
from all co-authors. M.P., C.D., K.A.R., N.J., P.O., C.E.W and P.D.S. provided support to the 48
study including analysis and/or microbiology expertise and/or clinical supervision. 49
50
Page 17 of 34
For Review Only
3
Funding support: The project was funded by Cystic Fibrosis Foundation Therapeutics USA 51
(BELL14AO). T.J.K. acknowledges National Health and Medical Research Council 52
(NHMRC) Early Career (GNT10884488) and ERS-EU RESPIRE2 Marie Sklodowska-Curie 53
Postdoctoral Research (#4571-2013) Fellowship support. L.D.K. acknowledges an NHMRC 54
Early Career Fellowship (APP1036620). R.E.S acknowledges The Prince Charles Hospital 55
Foundation and Advance Queensland PhD Scholarships. 56
57
List ONE descriptor number that best classifies the subject of your manuscript: 9.17 58
Cystic Fibrosis: Translational & Clinical Studies 59
Total word count for the body of the manuscript = 16201207 60
61
Page 18 of 34
For Review Only
4
Abstract 62
Introduction: The cystic fibrosis (CF) infection control guidelines recommend that people 63
with CF wear face-masks when in communal areas of hospitals. Recently, we reported short-64
term wear of face-masks (~10-minutes) reduced the release of Pseudomonas aeruginosa 65
aerosols during coughing. However, there is limited evidence to determine if face-masks 66
continue to be effective at reducing the release of infectious cough aerosols after longer wear 67
times. Methods: We recruited 25 people with CF and chronic P. aeruginosa infection and 10 68
healthy volunteers. All participants underwent up to 5 cough tests in a validated cough rig: 1) 69
uncovered cough; 2) coughing with surgical mask immediately applied; 3) coughing with 70
surgical mask worn for 10-minutes; 4) coughing with a surgical mask worn for 30-minutes; 5) 71
coughing with an N95 respirator worn for 10-minutes(optional). All participants underwent 72
up to 5 cough tests in a validated cough rig: 1) uncovered cough; 2) coughing with surgical 73
mask worn for 10-minutes; 3) coughing with surgical mask worn for 20-minutes; 4) coughing 74
with a surgical mask worn for 40-minutes; 5) coughing with an N95 respirator worn for 20-75
minutes (optional). The wear time of the mask included a 5-minute cough period in the 76
aerosol collection rigParticipants entered the cough rig and performed 2-minutes of tidal 77
breathing before and after a 5-minute cough period (additional 10-minutes was added to the 78
mask wear time). Sputum samples and cough aerosols were collected from participants with 79
CF as previously described. All participants rated their level of comfort post-test. Results: 80
Surgical masks and N95 respirators were effective at reducing the release of P. aeruginosa 81
aerosols during coughing after 40-minutes total wear and 20-minutes total wear respectively. 82
Both participants with CF and healthy volunteers rated the surgical masks as more 83
comfortable compared to N95 respirators. Conclusions: Surgical masks were the preferred 84
interface to wear as source control and were effective at reducing the release of P. aeruginosa 85
aerosols during coughing after 40-minutes of total wear. 86
Page 19 of 34
For Review Only
5
Introduction 87
Aerosol dissemination of respiratory pathogens may contribute to person-to-person 88
transmission in people with cystic fibrosis (CF) [1]. This evolving knowledge of transmission 89
modes has led to an update of the CF Foundation Infection and Prevention Control Guidelines 90
recommending people with CF wear surgical masks in communal hospital areas to prevent the 91
spread of CF respiratory pathogens [2]. These guidelines recommended the use of surgical 92
masks as source control despite limited evidence for this application. 93
94
We recently demonstrated that short-term wear of face-masks (10- minutes total wear) 95
significantly reduces the release of Pseudomonas aeruginosa aerosols during coughing in 96
people with CF [3]. These findings are consistent with an earlier study of people with CF that 97
reached the same conclusion after very short-term wear of surgical masks (worn for 21 98
coughs) [4]. These results and a recent editorial to our short-term mask wear study [5] support 99
our current aim to investigate the effectiveness, tolerability and functionality of face-masks as 100
source control after extended wear. 101
102
Methods 103
We recruited 25 people with CF and chronic P. aeruginosa infection [6] from the Adult 104
Cystic Fibrosis Centre, The Prince Charles Hospital, Brisbane, Australia. Ten healthy 105
volunteers were recruited from hospital and research staff to assess mask comfort and mask 106
weight change. All participants performed up to five randomly ordered tests in a validated 107
cough system [7]: 1) uncovered cough; 2) coughing with after immediate application of 108
surgical mask worn for 10-minutes); 3) coughing with surgical mask worn for after 210-109
minutes wear; 4) coughing with surgical mask worn for after 430-minutes wear; 5) coughing 110
Page 20 of 34
For Review Only
6
with N95 mask worn for after 120-minutes wear [3, 7]. The N95 test was an optional test 111
based on the poor comfort ratings observed in our earlier mask study [3]. 112
113
The duration of the mask wear tests were selected based on observation of patients moving 114
around communal areas of the hospital described here. Two types of masks were tested: 115
“surgical mask” [Catalogue # 47107; Halyard FLUIDSHIELD Level 3 Fog-Free Procedure 116
Mask (∆P<2.5), Georgia, USA] and “N95 mask” [Catalogue # 46827 (small) or 46727 117
(regular), Halyard FLUIDSHIELD N95 Particulate Filter Respirator and Surgical Mask, 118
Georgia, USA]. New masks were used for each test. Whilst wearing the mask, participants 119
were free to move around the study room (including able to talk and cough spontaneously) 120
until they performed the voluntary cough in the aerosol collection rig. The total wear time of 121
the masks included 1-minute positioning of the participant into the rig, 2--All participants 122
entered the cough rig and performed 2 minutes of tidal breathing with HEPA-filtered air, a 5-123
minute cough period, followed by another 2-minutes of tidal breathing before and after a five 124
minute cough period. Therefore, approximately 10 minutes was added to the mask wear time 125
(hereafter “total wear”). Cough aerosol collection, sputum processing and P. aeruginosa 126
genotyping were performed as previously described [1, 3, 8]. All participants rated their 127
comfort levels after each test [3, 9]. All masks were weighed before and following each test. 128
129
SPSS version 25 was used for statistical analysis. Participants with CF were stratified by the 130
amount of aerosol colony forming units (CFU) produced during the uncovered cough test: 131
high producer (total CFU was ≥10) or no/low producer (total CFU was <10) [3]. Categorical 132
variables were examined using Pearson Chi-squared test or Fisher’s Exact test. Continuous 133
variables were examined using a Student t-test or Mann-Whitney U test. CFU were log 134
transformed and the paired t-test examined changes over time. The McNemar-Bowker test 135
Page 21 of 34
For Review Only
7
was used to examine comfort scores over time. The Wilcoxon Signed Rank Test was used to 136
examine the change in mask weight over time. 137
138
Results 139
Microbiology results are provided in Table 1. P. aeruginosa was cultured from the sputum of 140
25/25 participants with CF and was cultured in cough aerosols during the uncovered cough 141
test of 20/25 participants. P. aeruginosa was cultured from cough aerosols of 9/20 142
participants during any of the surgical mask tests (10-minutesimmediate application, 20-143
minutes and 40-minutes total wear time) and 4/20 participants during the N95 mask test of 144
20-minutes total wear. The CFU were significantly reduced for the surgical masked tests 145
(surgical and N95) compared with the uncovered cough test (p<0.001). Between mask tests, 146
tThe CFU count remained similar as the duration of surgical mask wear increased (compared 147
to 10-minute total wear:immediate wear; 20-minute total wear, p=0.99; 40-minute total wear, 148
p=0.56) as well as between mask types (surgical mask worn for 20-minutes total versus N95 149
mask worn for 20-minutes total, p=0.19). The P. aeruginosa strain types found in the cough 150
aerosols were genetically indistinguishable from the paired sputum sample of each 151
participant. 152
153
Participants with CF rated surgical masks less comfortable than healthy volunteers for all test 154
durations (surgical mask: 10-minutes,immediate application, p=0.001; 20-minutes total wear, 155
p=0.007; 40-minutes total wear, p=0.023; N95: 20-minutes, p=0.018) (Table 2). Of the 156
participants with CF, 23/25 (92%) rated comfort as good during the uncovered cough test, 157
whereas 8/25 (32%) rated the 40-minutes surgical mask test as good comfort and 4/25 (16%) 158
rated the N95 mask test as good comfort (Table 2). Participants with CF were more tolerant of 159
mask wear (good comfort) after 10- and 20-minutes total wear time if they had higher lung 160
Page 22 of 34
For Review Only
8
function, yet this difference was lost after 40-minutes of surgical mask wear. For the healthy 161
participants, 9/10 (90%) rated the uncovered cough test as good and 8/10 (80%) rated the 40-162
minutes surgical mask test as good comfort whereas only 2/10 (20%) rated comfort as good 163
for the N95 mask (Table 2).Nevertheless, the comfort levels of surgical masks remained 164
similar in participants with CF and healthy volunteers as the test duration increased (Table 2). 165
Both groups rated the N95 mask as uncomfortable (p>0.99). 166
The change in mask weight for each test ranged from no weight change to a maximum weight 167
change of 0.02g. This change in mask weight was comparable between participants with CF 168
and healthy volunteers (surgical mask: 10-minutes, p=0.054; 20-minutes, p=0.050; 40-169
minutes, p=0.12). Similarly, when the change is mask weights for each test were compared 170
there was no statistical difference: between surgical mask tests (10-minutes versus 20-171
minutes, p=0.73; 20-minutes versus 40-minutes, p=0.25) and between mask types (20-172
minutes: surgical mask versus N95 mask, p=0.21) (Table 2). There was a minor increase in 173
surgical mask weight (median change, 0.01g) after 40-minutes compared with 10-minutes 174
wear (p=0.031) (Table 2). 175
The change in mask weight for each test was comparable between participants with CF and 176
healthy volunteers (surgical mask: immediate application, p=0.054; 20-minute total wear, 177
p=0.050; 40-minute total wear, p=0.12), between 2/3 surgical mask duration tests (immediate 178
application versus 20-minute total wear, p=0.73; 20-minute total wear versus 40-minute total 179
wear, p=0.25) and between mask types (20-minute total wear: surgical mask versus N95 180
mask, p=0.21). There was an increase in surgical mask weight after 40-minutes total wear 181
compared with immediate application (p=0.031). 182
183
Discussion 184
Page 23 of 34
For Review Only
9
Our study demonstrates that face masks worn for clinically-relevant time periods are effective 185
at reducing the release of potentially infectious aerosols during coughing in people with CF. 186
These results extend upon our earlier observations when the duration of mask wear was 187
shorter [3] and further support the CF Foundation recommendations regarding the use of 188
surgical masks to interrupt the spread of viable aerosols in communal hospital areas [2]. 189
190
Surgical masks were the preferred mask for source control in terms of comfort, which is 191
similar to our previous findings [3].These results extend upon our earlier observations that 192
demonstrated surgical masks and N95 masks were both effective at reducing the release of 193
infectious cough aerosols when the duration of mask wear was shorter [3]. Therefore, the 194
outcomes of our earlier mask study and the current study demonstrate that surgical masks are 195
effective and tolerable as source control. These studies support the CF Foundation (USA) 196
recommendations regarding the use of surgical masks to interrupt the dispersal of viable 197
aerosols in the hospital setting [2]. 198
199
Surgical masks were the preferred mask type for source control in terms of comfort, which is 200
similar to our recent study [3]. In contrast, the N95 mask was rated uncomfortable by ~50% 201
of our participants with CF and this was also similar to what was reported in our earlier mask 202
study where ~60% of participants with CF rated the N95 mask comfort as poor [3]. In 203
comparison, the surgical mask comfort was rated as good/acceptable comfort when worn for 204
10-minutes [3]. The healthy volunteers tolerated the surgical masks better than the 205
participants with CF and within the participants with CF, those with higher lung function 206
tolerated surgical masks better also. Furthermore, when the comfort of surgical masks was 207
assessed after extended wear in this cohort, a major finding was that the comfort ratings 208
remained unchanged regardless of wear time for both people with and without CF. Therefore, 209
Page 24 of 34
For Review Only
10
surgical masks are not only effective but are also well tolerated with participants rating them 210
as of sufficient or good comfort after 40-minutes total wear. 211
212
An accompanying editorial of our recent mask study [3] questioned if mask dampness may 213
affect the ability of the mask to function as source control after prolonged wear times [5]. The 214
CF infection control guidelines indicate that masks being used as source control should be 215
replaced when damp [2] and excessive moisture accumulation was a common reason for 216
surgical mask replacement in people with tuberculosis using surgical masks as source control 217
[10]. Our data indicates that although there was evidence of surgical mask moisture 218
accumulation after 40-minutes total wear (estimated by increased weight), the surgical mask 219
continued to function effectively as source control mitigating this concern. 220
221
There are several limitations to this study:. 1)Firstly, Tthe infectious dose of P. aeruginosa is 222
unknown and therefore the infection risk cannot be determined;. 2)Secondly, Pparticipants 223
remained in view of staff while wearing the masks and this may have modified the extent to 224
which participants interfered with the mask leading to an incorrect estimation on the masks 225
protective effects; 3). Participants were seated during the cough testing and this may have 226
impacted on the ability of the participant to cough freely during the testing; 4)Thirdly, The 227
number of coughs were counted for each test. While some participants did experience 228
episodes of spontaneous cough during testing, this was not recorded separately as 229
differentiating between spontaneous and voluntary cough would be an arbitrary ‘call’. 230
Therefore, the effects of spontaneous cough on aerosol dispersion is unknown and 231
furthermore, the estimation of the protective effects of the face masks may be inaccurate; 5) 232
the The effectiveness and tolerability of masks is reported in adults only and thus, these 233
characteristics need to be studied in children; 6). Lastly, Oour study had a maximum total 234
Page 25 of 34
For Review Only
11
wear time of 40-minutes and the effectiveness of masks worn for longer periods is unknown; 235
7) The inwards protection of the masks was not tested in our study and has been reported in a 236
recent systematic review as an under-studied area [11]. To undertake such studies would not 237
be considered ethical.. 238
239
240
Our study confirms the effectiveness of surgical masks at reducing the release of P. 241
aeruginosa cough aerosols in people with CF and provides evidence of patient tolerability and 242
functionality of these masks as source control after 40-minutes of total wear. 243
244
Acknowledgements: We thank Dr Farhad Salimi for his aerosol support to the study. We 245
thank Greg Flohr and staff from the Central Pathology Laboratory (Royal Brisbane and 246
Women’s Hospital), Pathology Queensland for microbiological support to the study. We 247
thank the Adult CF Centre team in supporting recruitment to the studies. We also thank all the 248
participants in the study for supporting the work. 249
250
Page 26 of 34
For Review Only
12
Table 1: Demographic and clinical characteristics of the study participants 251
Group Production level in CF participants
Healthy CF p-value
No/low
(<10 CFU)
High
(≥ 10 CFU) p-value
(n = 10) (n = 25)
(n = 14) (n = 11)
Participant characteristics
Age, years, mean (SD) 37.3 (12.3) 33.3 (9.0) 0.29 36.7 (9.3) 28.9 (6.9) 0.029
Sex, male, n (%) 6 (60.0) 15 (60.0) 1.00 9 (64.3) 6 (54.5) 0.70
Body mass index (BMI), kg/m2, mean (SD) 24.6 (3.5) 22.8 (3.2) 0.14 22.5 (3.7) 23.1 (2.6) 0.63
FEV1 % predicted, mean (SD) 92.6 (9.2) 53.8 (20.8) <0.001 54.2 (23.2) 53.3 (18.2) 0.91
Mean P. aeruginosa sputum concentration, x 107 CFU/mL (95% CI)a n/a 5.2 (2.1 –
12.9) - 1.9 (0.7 – 5.7) 18.3 (4.7 – 70.9) 0.008
Participants with P. aeruginosa detected in cough aerosols
Uncovered cough test
n (%) n/a 20 (80.0) - 9 (64.3) 11 (100.0)
Mean CFU (95% CI)a
17 (7 - 43)
2 (1 – 4) 75 (34 – 165)
Surgical mask tests
Immediate application
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Total CFU (95% CI)a
4 (1 – 10)
1 5 (1 – 13)
20-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)
a
4 (1 – 10)
1 4 (1 – 11) 0.99
d
40-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
1 4 (1 – 9) 0.56
e, 0.64
f
N95 mask test~
20-minutes total wear (n=23)
3 (1 – 7)
n (%) n/a 4 (17.4) - 0 (0.0)b 4 (40.0)
c
Mean CFU (95% CI)
a
2 (0 – 6)
n/a 2 (0 – 6) 0.19
g
Page 27 of 34
For Review Only
13
Definitions: FEV1, forced expiratory volume in 1 second; CFU, colony forming unit; CFU/mL, CFU per millilitre of sputum; SD, standard deviation; 252
CI, confidence interval, n/a, not applicable ~ Optional test 253
254 ageometric mean 255
bparticipant number (n) = 13 256
cparticipant number (n) = 10 257
dSurgical masks (geometric mean CFU): immediate versus 20 minutes total wear 258
eSurgical masks (geometric mean CFU): immediate versus 40 minutes total wear 259
fSurgical masks (geometric mean CFU): 20 minutes total wear versus 40 minutes total wear 260 gMean CFU surgical mask 20 minutes total wear versus mean CFU N95 mask 20 minutes total we261 Formatted: Left
Page 28 of 34
For Review Only
14
Table 2: Surgical mask comfort ratings over time 262
Mask comfort Coughing wearing a surgical mask – Immediate application
Coughing wearing a surgical mask – 20-minutes total wear Poor Sufficient Good p-value
Poor 1 1 0 0.51
Sufficient 0 12 1
Good 0 2 18
Coughing wearing a surgical mask – 40-minutes total wear
Poor 1 2 0 0.15
Sufficient 0 12 4
Good 0 1 15
Table 1: Demographic and clinical characteristics of the study participants 263
Group Production level in CF participants
Healthy CF p-value
No/low
(<10 CFU)
High
(≥ 10 CFU) p-value
(n = 10) (n = 25)
(n = 14) (n = 11)
Participant characteristics
Age, years, mean (SD) 37.3 (12.3) 33.3 (9.0) 0.29 36.7 (9.3) 28.9 (6.9) 0.029
Sex, male, n (%) 6 (60.0) 15 (60.0) 1.00 9 (64.3) 6 (54.5) 0.70
Body mass index (BMI), kg/m2, mean (SD) 24.6 (3.5) 22.8 (3.2) 0.14 22.5 (3.7) 23.1 (2.6) 0.63
FEV1 % predicted, mean (SD) 92.6 (9.2) 53.8 (20.8) <0.001 54.2 (23.2) 53.3 (18.2) 0.91
Mean P. aeruginosa sputum concentration, x 107 CFU/mL (95% CI)
a n/a
5.2 (2.1 –
12.9) - 1.9 (0.7 – 5.7) 18.3 (4.7 – 70.9) 0.008
Participants with P. aeruginosa detected in cough aerosols
Uncovered cough test
n (%) n/a 20 (80.0) - 9 (64.3) 11 (100.0)
Mean CFU (95% CI)a
17 (7 - 43)
2 (1 – 4) 75 (34 – 165) <0.001
d
Surgical mask tests
10-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
4 (1 – 10)
1 5 (1 – 13)
Page 29 of 34
For Review Only
15
20-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
4 (1 – 10)
1 4 (1 – 11) 0.99
e
40-minutes total wear
n (%) n/a 9 (36.0) - 1 (7.1) 8 (72.7)
Mean CFU (95% CI)a
1 4 (1 – 9) 0.56
f, 0.64
g
N95 mask test~
20-minutes total wear (n=23)
3 (1 – 7)
n (%) n/a 4 (17.4) - 0 (0.0)b 4 (40.0)
c
Mean CFU (95% CI)
a
2 (0 – 6)
n/a 2 (0 – 6) 0.19
h
Definitions: FEV1, forced expiratory volume in 1 second; CFU, colony forming unit; CFU/mL, CFU per millilitre of sputum; SD, standard deviation; 264
CI, confidence interval, n/a, not applicable ~ Optional test 265
266 ageometric mean 267
bparticipant number (n) = 13 268
cparticipant number (n) = 10 269
dUncovered cough (geometric mean CFU) compared to each surgical mask test (geometric mean CFU) 270
eSurgical masks (geometric mean CFU): 10-minutes versus 20-minutes total wear 271 fSurgical masks (geometric mean CFU): 10-minutes versus 40-minutes total wear 272
gSurgical masks (geometric mean CFU): 20-minutes versus 40-minutes total wear 273
hMean CFU surgical mask 20-minutes total wear versus mean CFU N95 mask 20-minutes total wear 274
Page 30 of 34
For Review Only
16
Table 2: Summary of mask properties 275
Mask comfort Mask weight change
Mask properties Healthy
n (%)
CF
n (%) p-value
All participants
Median (IQR)
p-value
Uncovered cough comfort level 1.00 n/a n/a
Poor 0 (0.0 %) 0 (0.0 %)
Sufficient 1 (10.0 %) 2 (8.0 %)
Good 9 (90.0 %) 23 (92.0 %)
Coughing wearing a surgical mask – 10-minutes total wear 0.001 0.01g (0.00g – 0.02g) n/a
Poor 1 (10.0 %) 0 (0.0 %)
Sufficient 0 (0.0 %) 15 (60.0 %)
Good 9 (90.0 %) 10 (40.0 %)
Coughing wearing a surgical mask – 20-minutes total wear 0.007 0.01g (0.00g – 0.02g) 0.73a
Poor 1 (10.0 %) 1 (4.0 %)
Sufficient 0 (0.0 %) 13 (52.0 %)
Good 9 (90.0 %) 11 (44.0 %)
Coughing wearing a surgical mask – 40-minutes total wear 0.023 0.02g (0.01g – 0.03g) 0.25b, 0.031
c
Poor 1 (10.0 %) 2 (8.0 %)
Sufficient 1 (10.0 %) 15 (60.0 %)
Good 8 (80.0 %) 8 (32.0 %)
Coughing wearing N95 mask -20-minutes total wear 0.018 0.02g (0.00g – 0.04g) 0.21d
Poor 0 (0.0 %) 11 (47.8 %)
Sufficient 7 (77.8 %) 8 (34.8 %)
Good 2 (22.2 %) 4 (17.4 %)
276 aSurgical mask weight change: 10-minutes versus 20-minutes total wear 277 bSurgical mask weight change: 20-minutes versus 40-minutes total wear 278
cSurgical mask weight change: 10-minutes versus 40-minutes total wear 279
dMask weight change after 20-minutes wear: surgical mask versus N95 mask 280
Page 31 of 34
For Review Only
17
281
Page 32 of 34
For Review Only
18
References: 282
1. Knibbs, L.D., Johnson, G.R., Kidd, T.J., Cheney, J., Grimwood, K., Kattenbelt, J.A., 283
O'Rourke, P.K., Ramsay, K.A., Sly, P.D., Wainwright, C.E., Wood, M.E., Morawska, 284
L., and Bell, S.C. Viability of Pseudomonas aeruginosa in cough aerosols generated by 285
persons with cystic fibrosis. Thorax. 2014;69(8):740-5 286
2. Saiman, L., Siegel, J.D., LiPuma, J.J., Brown, R.F., Bryson, E.A., Chambers, M.J., 287
Downer, V.S., Fliege, J., Hazle, L.A., Jain, M., Marshall, B.C., O'Malley, C., Pattee, 288
S.R., Potter-Bynoe, G., Reid, S., Robinson, K.A., Sabadosa, K.A., Schmidt, H.J., Tullis, 289
E., Webber, J., and Weber, D.J. Infection prevention and control guideline for cystic 290
fibrosis: 2013 update. Infect Control Hosp Epidemiol. 2014;35 Suppl 1:S1-s67 291
3. Wood, M.E., Stockwell, R.E., Johnson, G.R., Ramsay, K.A., Sherrard, L.J., Jabbour, N., 292
Ballard, E., O'Rourke, P., Kidd, T.J., Wainwright, C.E., Knibbs, L.D., Sly, P.D., 293
Morawska, L., and Bell, S.C. Face Masks and Cough Etiquette Reduce the Cough 294
Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis. Am 295
J Respir Crit Care Med. 2018;197(3):348-355 296
4. Driessche, K.V., Hens, N., Tilley, P., Quon, B.S., Chilvers, M.A., de Groot, R., Cotton, 297
M.F., Marais, B.J., Speert, D.P., and Zlosnik, J.E. Surgical masks reduce airborne 298
spread of Pseudomonas aeruginosa in colonized patients with cystic fibrosis. Am J 299
Respir Crit Care Med. 2015;192(7):897-9 300
5. Simmonds, N.J. and Bush, A. The Man in the Paper Mask: One (Mask) for All and All 301
for . . . Cystic Fibrosis? Am J Respir Crit Care Med. 2018;197(3):281-283 302
6. Ramsay, K.A., Sandhu, H., Geake, J.B., Ballard, E., O'Rourke, P., Wainwright, C.E., 303
Reid, D.W., Kidd, T.J., and Bell, S.C. The changing prevalence of pulmonary infection 304
in adults with cystic fibrosis: A longitudinal analysis. J Cyst Fibros. 2017;16(1):70-77 305
Page 33 of 34
For Review Only
19
7. Johnson, G.R., Knibbs, L.D., Kidd, T.J., Wainwright, C.E., Wood, M.E., Ramsay, K.A., 306
Bell, S.C., and Morawska, L. A Novel Method and Its Application to Measuring 307
Pathogen Decay in Bioaerosols from Patients with Respiratory Disease. PLoS One. 308
2016;11(7):e0158763 309
8. Syrmis, M.W., Kidd, T.J., Moser, R.J., Ramsay, K.A., Gibson, K.M., Anuj, S., Bell, 310
S.C., Wainwright, C.E., Grimwood, K., Nissen, M., Sloots, T.P., and Whiley, D.M. A 311
comparison of two informative SNP-based strategies for typing Pseudomonas 312
aeruginosa isolates from patients with cystic fibrosis. BMC Infect Dis. 2014;14:307 313
9. Gregoretti, C., Confalonieri, M., Navalesi, P., Squadrone, V., Frigerio, P., Beltrame, F., 314
Carbone, G., Conti, G., Gamna, F., Nava, S., Calderini, E., Skrobik, Y., and Antonelli, 315
M. Evaluation of patient skin breakdown and comfort with a new face mask for non-316
invasive ventilation: a multi-center study. Intensive Care Med. 2002;28(3):278-84 317
10. Dharmadhikari, A.S., Mphahlele, M., Stoltz, A., Venter, K., Mathebula, R., Masotla, T., 318
Lubbe, W., Pagano, M., First, M., Jensen, P.A., van der Walt, M., and Nardell, E.A. 319
Surgical face masks worn by patients with multidrug-resistant tuberculosis: impact on 320
infectivity of air on a hospital ward. Am J Respir Crit Care Med. 2012;185(10):1104-9 321
11. MacIntyre, C.R., and Chughtai, A.A. Facemasks for the prevention of infection in 322
healthcare and community settings. BMJ. 2015;350:h694 323
Page 34 of 34