1180 infection control & hospital epidemiology october 2015, vol. 36, no. 10
undesirable outcomes would require an enormous study population. For instance, a 10% reduction in MRSA coloniza- tion rates, which for this study population equates to an absolute risk reduction of 0.4% or 1 of 250 babies per month, would be detected at 80% power only with 7,984 patients studied throughout their NICU stay. Single-patient rooms might fail to prevent MRSA coloni-
zation and CLOS for several reasons. With single-patient rooms spread further apart in space, horizontal spread of infections would seem to decrease. If, however, hand-hygiene practices are universally followed and fomites carried by healthcare workers are limited, this may reduce the effect of spreading patients out geographically. Over the course of this study, there was high hand hygiene compliance, which may have diminished the impact of bed configuration, limiting generalizability for units in which hand hygiene compliance is low. In addition, nonhorizontal spread of pathogens may contribute sufficient amounts of infectious “noise” to the data, decreasing the ability to detect the horizontal spread of infec- tious material. Such nonhorizontal methods include vertical transmission at birth and contact with visitors, including parents and family, which would not be expected to differ on the basis of room configuration. Our study indicates that high census periods are positively correlated with greater MRSA colonization only in single-patient room configurations. Although bed occupancy rates have been shown to correlate positively with MRSA colonization,28 the mechanisms leading to this configuration-specificresultremainto be determined. This study has several limitations. First, the data were collected
retrospectively. However, a large prospective randomized study of this nature would be prohibitive given the constraints of patient staffing and physical space within a NICU environment. Second, although bed configuration might reduce horizontal spread of pathogens, such layouts might not mitigate other mechanisms of transfer, such as visitor-to-patient transmission or interhost transfer,29 which were not addressed. In a compa- nion project conducted at the same time as this study, stools of 3 infants in open-unit rooms in the vicinity of 2 infants with group B streptococci sepsis, and 1 infant in the vicinity of an infant with Serratia marcescens sepsis, contained the infecting strain, suggesting that interhost spread is better detected by focusing on colonization than on culture-proven sepsis.29 Finally, our study was not designed to address culture-negative sepsis. Isolation of bona fide bloodstream pathogens is a challenge in NICUs because the volume of blood submitted for culturemight be inadequate to confirm an etiologic agent.30 Identifying such cases in retrospect is difficult, and hence, we might have under- estimated actionable events that occurred in either or both of the bed configurations. Using a broader definition than CLOS, however, could have overestimated sepsis events. Considerations beyond infection have been put forth regard-
ing choice of room configuration. Some studies demonstrate that single-patient rooms modestly improve breast-feeding initiation, are quieter, and have better air quality,9 whereas
others have highlighted the larger space requirement,31 resulting in larger NICUs, greater construction costs,32,33 and longer distances traveled responding to emergencies, as well as issues with communication, patient monitoring,31,34 and nurse isolation.35 Although parent satisfaction scores, visitation rates, and noise levels favor single-patient rooms,31,35–37 parental stress and neonatal language and motor development favor open units.38,39 In conclusion, single-patient rooms did not provide pro-
tection against MRSA colonization, CLOS, and the combined outcome of CLOS or death in a NICU environment. Although single-patient rooms may have other benefits, neonates in this bed configuration were as likely as those in open-units to acquire these infections and the morbidities and mortality that come with them. In this analysis, average census positively correlated with MRSA colonization only within the single- patient room configuration. Increased vigilance is required during periods of high census, with particular attention paid to hand hygiene, the only variable that affected MRSA coloniza- tion. Further studies are warranted to assess how facility design might reduce the burden of sepsis and MRSA colonization in this high-risk population.
acknowledgments
We thank Alexis Elward, MD, and the Infection Control Committee at St. Louis Children’s Hospital for their expertise, MRSA colonization data, and hand hygiene compliance data; Rachel Frobel for the training and technical expertise in repetitive sequence polymerase chain reaction; and the St. Louis Children’s Hospital Office of Planning and Business Development for the NICU billing and coding data used in this study. Finally, none of this would be possible without the cooperation of the staff of the NICU and the families of our patients at St. Louis Children’s Hospital. Financial support. National Institutes of Health (grant UH3 AI083265). Potential conflicts of interest. All authors report no conflicts of interest
relevant to this article. Address correspondence to Samuel Julian, MD, Washington University
School of Medicine, Department of Pediatrics, 660 S. Euclid Ave, Campus Box 8116, St. Louis, MO 63110 (
julian_s@kids.wustl.edu).
supplementary material
To view supplementary material for this article, please visit
http://dx.doi.org/10.1017/ice.2015.144
references 1. Kochanek KD, Xu J, Murphy SL, Miniño AM, Kung HC. Deaths: final data for 2009. Nat Vital Stat Rep 2012;60:1–117.
2. Heron M. Deaths: leading causes for 2008. Nat Vital Stat Rep 2012;60:1–94.
3. Stoll BJ, Hansen NI, Adams-Chapman I, et al. Neurodevelop- mental and growth impairment among extremely low- birth-weight infants with neonatal infection. JAMA 2004;292: 2357–2365.
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