Table 1.

Key Studies that Examine the Role of Environment in Patient Infectious Disease Outcomes

Relation	Organism	Comments	Reference
Increased Acquisition
ENV - > Patient	MRSA	Outbreak of MRSA in hospital that lasted 2 years was found in hospital dust with the same genotype.	[22]
ENV - > Patient	Not specific	Patients assigned to shared bay rooms had a 21% greater relative risk of a central line infection (p = 0.005), compared with patients assigned to private rooms. At the hospital level, a 10% increase in private rooms was associated with an 8.6% decrease in central line infections (p < 0.001), regardless of individual patients’ room assignment.	[23]
ENV - > Patient	MRSA	Three of 26 patients who acquired MRSA while in the intensive care unit acquired MRSA from the environment, strains from the patients and their immediate environment were indistinguishable	[24]
ENV- > HCW	VRE	Contact with contaminated surfaces in the rooms of colonized patients results in transfer of VRE to gloved hands, despite cleaning with disinfectants	[25]
ENV - > HCW	C. difficile	Increasing levels of environmental contamination was positively associated with increasing amounts of C. difficile on the hands of healthcare workers, particularly for environmental sites that patients touch	[26]
Patient - > ENV	C. difficile	Surfaces in rooms exposed to a C. difficile patient had significantly increased odds of being contaminated with C. difficile, compared to surfaces in unexposed patient rooms	[27]
Patient - > HCW	MRSA	Two-thirds of staff enter a room containing an MRSA patient will acquire the patient’s strain on gloved hands or apron, even without touching patient directly (40%)	[28]
Patient - > Patient	MRSA, VRE	Admission to a room previously occupied by an MRSA-positive patient or a VRE-positive patient significantly increased the odds of acquisition for MRSA and VRE.	[29]
Patient - > Patient	C. difficile	Prior room occupant with CDI was a positive risk factor for new patient CDI acquisition, hazard ratio 2.35 p = .01	[30]
Patient - > Patient	Several (MRSA, C. difficile, VRE)	Pooled acquisition odds ratio of 2.14 (95% confidence interval (CI), 1.65e2.77) for several bacteria from prior occupants, Gram positive 1.89 (95% CI: 1.62–2.21)	[31]
Patient - > ENV - > HCW	MRSA	In the colonized patient’s room, HCW exposure occurred more predominantly through the indirect (patient to surfaces to HCW) mode compared to the direct (patient to HCW) mode.	[32]
Cleaning/Removal Reduces Human Acquisition
ENV - > Patient	MRSA	Enhanced cleaning during an outbreak decreased the number of new affected patients, stopped outbreak, and saved an estimated £28,000.	[22]
ENV - > Patient	General	Lower infection rates associated with routine disinfection of surfaces (mainly floors)	[33]
ENV - > Patient	C. difficile	Daily disinfectant high touch surfaces and dedicated cleaning staff reduced CDI positive cultures by 60%	[34]
ENV - > Patient	C. difficile	Hydrogen peroxide vapor decontamination reduced CDI rate by 37%	[35]
ENV - > Patient	VRE	Hydrogen peroxide vapor reduced VRE by 80%	[36]
ENV - > Patient	MRSA	Reduction in acquired MRSA infections with enhanced targeted cleaning compared to routine cleaning, despite higher MRSA patient-days and bed occupancy rates during enhanced cleaning periods (P = 0.032: 95% CI 7.7, 92.3%). Genotyping identified indistinguishable strains from both hand-touch sites and patients	[37]
ENV - > HCW	VRE	Decreasing VRE contamination of environmental surfaces decreases hand colonization of VRE and VRE acquisition rates	[38]

MRSA methicillin-resistant Staphylococcus aureus, CDI C. difficile infection, VRE vancomycin-resistant Enterococcus, ENV hospital environment, HCW healthcare worker