Sustained reduction of microbial burden on common hospital surfaces through introduction of copper

Abstract

The contribution of environmental surface contamination with pathogenic organisms to the development of health care-associated infections (HAI) has not been well defined. The microbial burden (MB) associated with commonly touched surfaces in intensive care units (ICUs) was determined by sampling six objects in 16 rooms in ICUs in three hospitals over 43 months. At month 23, copper-alloy surfaces, with inherent antimicrobial properties, were installed onto six monitored objects in 8 of 16 rooms, and the effect that this application had on the intrinsic MB present on the six objects was assessed. Census continued in rooms with and without copper for an additional 21 months. In concert with routine infection control practices, the average MB found for the six objects assessed in the clinical environment during the preintervention phase was 28 times higher (6,985 CFU/100 cm(2); n = 3,977 objects sampled) than levels proposed as benign immediately after terminal cleaning (<250 CFU/100 cm(2)). During the intervention phase, the MB was found to be significantly lower for both the control and copper-surfaced objects. Copper was found to cause a significant (83%) reduction in the average MB found on the objects (465 CFU/100 cm(2); n = 2714 objects) compared to the controls (2,674 CFU/100 cm(2); n = 2,831 objects [P < 0.0001]). The introduction of copper surfaces to objects formerly covered with plastic, wood, stainless steel, and other materials found in the patient care environment significantly reduced the overall MB on a continuous basis, thereby providing a potentially safer environment for hospital patients, health care workers (HCWs), and visitors.

Figures

Fig 1

Representative frequently touched objects and their respective placements in the ICU.

Fig 2

Assessment of the inherent microbial burden associated with frequently touched objects. The average concentrations of bacteria (classified by type) were determined from samples collected from six inanimate objects for a period of 23 months (n = 668 rooms). Bed rails, dark blue bars; call buttons (hospitals 1 and 3) and computer mice (hospital 2), red bars; arms of chairs, yellow bars; tray tables, light blue bars; data input devices (base of monitor bezel [hospitals 1 and 2] and palm rest of laptop computer [hospital 3]), purple bars; IV poles, gray bars. (The call button data represent values obtained from call buttons at 2 sites and from a computer mouse at the third due to the absence of a call button at that site.)

Fig 3

Copper lowered the MB found on common, frequently touched objects. (A) Comparison of the average MBs between rooms with (green bars; n = 501 rooms) and without (red bars; n = 511 rooms) copper-surfaced items. Samples were collected over a period of 21 months, processed, and statistically analyzed as described in Materials and Methods (*, P < 0.05). (B [noncopper objects] and C [copper objects]). Average concentrations of bacteria (classified by type) recovered from bed rails (dark blue bars), call buttons (hospitals 1 and 3) and computer mice (hospital 2) (red bars), arms of chairs (yellow bars), tray tables (light blue bars), data input devices (base of monitor bezel [hospitals 1 and 2] and palm rest of laptop computer [hospital 3]) (purple bars), and IV poles (gray bars). (The call button data represent values obtained from call buttons at 2 sites and from a computer mouse at the third due to the absence of a call button at that site.)

Fig 4

Frequency distribution of the MB resident on all objects (classified by type) during the intervention. The MBs observed for each sample from rooms with copper-surfaced objects are represented on the left; those observed for each sample from rooms without copper-surfaced objects are represented on the right. The concentration of bacteria observed for each sample was placed into one of three categories, 0 CFU/100 cm2 (green bars), 1 to 250 CFU/100 cm2 (yellow bars), and >250 CFU/100 cm2 (red bars), and the final percentage, rounded to the nearest whole number, of each category was determined.