The Role of Contaminated Surfaces in the Transmission of Nosocomial Pathogens - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 29

MRSA Methicillin-resistant Staphylococcus aureus
MDR-GNRs Multidrug-resistant Gram-negative rods
MDROs Multidrug-resistant organisms

NTD “No-touch” automated room disinfection

RLU Relative light unit

VRE Vancomycin-resistant enterococci

3.1 Introduction

Contamination of hospital equipment, medicines and water supplies with
hospital pathogens is a well-recognized cause of common-source outbreaks of
infection [ 3 , 4 ]. There is extensive guidance on prevention and control of such
contamination available from manufacturers, Specialist Societies and Health
Departments and often a legal requirement to comply with associated health and
safety regulations. In contrast, the degree to which ongoing contamination of
the surface environment contributes to the development of healthcare-associated
infections (HAI) is unclear and approaches to control uncertain.
Hospital patients shed pathogens into their surrounding environments but there
is debate over the importance of the resulting surface contamination as a source for
subsequent transmission. Since the 1950s, hospital design and hygienic practices
have been largely directed at controlling nosocomial pathogens contaminating air,
hands, equipment and surfaces [ 5 ]. However, several studies in the 1970s and early
1980s suggested that the hospital environment contributed negligibly to endemic
transmission [ 6 , 7 ]. Routine surveillance cultures of the hospital environment were
regarded as unjustified and the significance of environmental cultures made during
outbreaks was questioned [ 8 , 9 ]. Consequently, the frequency of routine environ-
mental sampling reduced from three quarters of US hospitals in 1975 [ 8 ] to virtually
none today. Indeed, in recent USA Centers for Disease Control and Prevention
(CDC) guidelines, environmental sampling is currently recommended only during
outbreaks [ 10 ]. Recently, however, there has been a reassessment of the role
of contaminated surfaces in the transmission of nosocomial pathogens [ 4 , 11 ].
The epidemiological finding that admission to a room previously occupied by
certain environmentally-associated pathogens such as Clostridium difficile ,
methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant entero-
cocci (VRE) and Acinetobacter baumannii increases the risk of acquisition for
incoming patients is perhaps the most compelling evidence that contaminated
surfaces contribute to transmission [ 1 , 2 ]. Furthermore, intervention studies dem-
onstrate that improvements to terminal (discharge) disinfection mitigate - to a
lesser or greater degree - the increased risk from the prior occupant cements the
epidemiological association [ 12 , 13 ].