Persistence of Nosocomial Pathogens Requires Proper Environmental Cleaning

The jury is still out in terms of industry agreement on the degree to which the healthcare environment serves as a reservoir for a variety of infectious microorganisms. In its 2003 guidelines addressing environmental infection control in healthcare facilities, the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the Centers for Disease Control and Prevention (CDC) notes that this environment “is rarely implicated in disease transmission except in the immunocompromised population.”¹ However, HICPAC adds, “Inadvertent exposures to environmental opportunistic pathogens (e.g., Aspergillus spp. and Legionella spp.) or airborne pathogens (e.g., Mycobacterium tuberculosis and varicella-zoster virus) may result in infections with significant morbidity and/or mortality. Lack of adherence to established standards and guidance (e.g., water quality in dialysis, proper ventilation for specialized care areas such as operating rooms, and proper use of disinfectants) can result in adverse patient outcomes in healthcare facilities.”¹

There is no dispute that proper, effective surface cleaning and disinfection in healthcare facilities is one of the most important ways to prevent and control healthcare-acquired infections (HAIs). In light of recent studies that point to the persistence of some bacteria, viruses and fungi, surface cleaning in the healthcare environment takes on a new sense of urgency. Researchers examined the persistence of different nosocomial pathogens on inanimate surfaces and reported that these microorganisms may survive and even thrive on surfaces for months and can thereby be a continuous source of transmission if no regular preventive surface cleaning and disinfection is performed.²

Researchers found that most gram-positive bacteria, such as Enterococcus spp. (including VRE), Staphylococcus aureus (including methicillin- resistant), or Streptococcus pyogenes, survive for months on dry surfaces. Many gram-negative species, such as Acinetobacter spp., Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Serratia marcescens, or Shigella spp., can also survive for months. Mycobacteria, including Mycobacterium tuberculosis, and spore-forming bacteria, including Clostridium difficile, can also survive for months on surfaces. Candida albicans, a significant nosocomial fungal pathogen, can survive up to four months on surfaces.²

The researchers also found that most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhinovirus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, poliovirus or rotavirus, persist for approximately two months. Bloodborne viruses, such as hepatitis B virus (HBV), can persist for more than one week. Herpes viruses have been shown to persist from only a few hours up to seven days.²

The number and types of microorganisms present on environmental surfaces are influenced by the number of people in the environment, the amount of activity, the amount of moisture, the presence of material capable of supporting microbial growth, the rate at which organisms suspended in the air are removed, and the type of surface and orientation (horizontal or vertical). Strategies for cleaning and disinfecting surfaces in patient-care areas take into account the potential for direct patient contact, the degree and frequency of hand contact, and potential contamination of the surface with body substances or environmental sources of microorganisms, such as soil, dust and water.¹

References

1. Centers for Disease Control and Prevention. Guidelines for Environmental Infection Control in Health-Care Facilities. 2003.

2. Kramer A, Schwebke I, and Kamp G. How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infectious Diseases. 6:130;2006.