922 Table 3. Characteristics of Clostridium difficile Samples Successfully Ribotyped (N=20) Estimated Spore Count 16S


Ward-Rooma A-2 A-2 A-2 A-2 A-4 A-4 A-5 A-5 B-7 B-8 B-8


B-11 B-11 B-11 B-11 B-10 B-10 B-12 B-12 B-12


Room Risk of Contaminationb High High High High High High Low Low Low Low Low High High High High Low Low High High High


Type


Floor Floor


Bedrail Bedrail Floor


Bedrail Floor Floor Floor Floor Floor Floor Floor


Bedrail Bedrail Floor Floor Floor Floor


Bedrail


Surface Area Small Large Small Large Large Small Small Large Large Small Large Small Large Small Large Small Large Small Large Large


Ribotypes


027, PR18099 027


027, PR18101 027


PR18099 014-0 400 400 015 015 015 015 015 015 015 015


015, 009 015 010


015, 010 qPCR 28.1


424.2 19.6


778.0 41.8 2.0 0


55.1 24.6


475.6 602.3


7,863.5


136,143.6 1,101.1 4,373.7 19.9


254.0 495.1


3,276.0 31.2


Toxin B qPCR


2.5 7.7 4.6 2.5 0.2 0 0 0


13.9 59.4 69.9


217.4 409.5 2.1


58.1 0


9.6 5.3


276.7 0


NOTE. qPCR, quantitative polymerase chain reaction. aNo positive samples were obtained from ward C. bLow, occupant had no receipt of antibiotics in prior 14 days; medium, occupant had receipt of antibiotics in prior 14 days; high, occupant had confirmed C. difficile infection.


dose required to infect 50% of mice (ID50) for C. difficile was 1hour ofexposureto5–10 culturable spores per square centimeter of cage floor.34 Future research should seek to identify the infectious dose for C. difficile for both healthy individuals and those at a risk of C. difficile infection due to antibiotic receipt and to define the maximum threshold of environmental density of C. difficile that confers an acceptably low risk of infection. Such environmental density thresholds could be used to better ascertain the acceptability of current hospital cleaning protocols. Our study has several limitations. First, it is a study of rooms


in a single hospital over 2 days of sampling and may not be generalizable to other hospitals. We lacked several covariates including antibiotic history prior to hospital admission and tim- ing of most recent cleaning prior to sample collection. However, these limitations were controlled for by the experimental design of our study, wherein sample surface area and sample type, our 2 exposures of primary interest, were compared to each other within rooms at the same point in time. Second, our small surface- area bedrail samples were selected from the head of the bedrail, while our large surface-area samples were chosen from the remainder of the bedrail, which could have led to a bias if spore density was higher or lowernearthe head of thebedrail.


In this study, we found that increased sample surface area


was associated with increased counts of spores recovered and increased proportions of samples that were positive. We also found that C. difficile contamination was common on hospital bedrails and floors and even more so in the rooms of patients with C. difficile infection. Future studies attempting to quantify the environmental density of C. difficile should consider using large surface-area samples whenever possible. Further study is required to better understand the role of contaminated hospital floors in the transmission of C. difficile infection.


Supplementary materials. To view supplementary material for this article, please visit https://doi.org/10.1017/ice.2018.103


Acknowledgments. The authors thank Kwaku Adomako and Arezou Saedi for assistance with research ethics approval, sample collection, and trans- portation, and Victoria Williams for assistance with coordinating sample collection.


Financial support. This study was funded by a grant from the Canadian Institutes for Health Research. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.


Kevin Antoine Brown et al


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140