INF ECTION P R EVENTION
Breaking the chain of cross-contamination
Dr. Kayleigh Cox-Nowak examines hand hygiene and effective environmental cleaning practices; particularly how the two are intrinsically linked in hospitals. She discusses the evidence and strategies aimed at breaking the chain of cross-contamination.
The transmission of COVID-19 (SARS-CoV-2) in healthcare settings continues to be an issue of concern. Effective hand hygiene and environmental cleaning are both key aspects of a strategic approach to prevent transmission of SARS-CoV-2, as well as other pathogens with the potential to cause nosocomial infection. Good hand hygiene practices and environmental cleaning are usually considered separately, but there is evidence which strongly links the two. Making contact with a contaminated surface and not performing hand cleansing adequately has been shown to facilitate the transmission of pathogens. Likewise, poor hand hygiene can lead to surface contamination.
Link between hands and surface contamination Contaminated surfaces are an established route of transmission for many nosocomial pathogens, including both bacteria and viruses; potentially resulting in onward contamination of hands or equipment,1
Pre-
COVID data suggests that the influenza virus, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS) may be shed into the environment and subsequently be transferred from surfaces to the hands of patients and healthcare staff. Hands contaminated by environmental surfaces can then lead to infection through touching the nose, eyes or mouth.1 SARS-CoV-2 can reach surfaces in the form of an aerosol and contamination can occur, for instance, by patients sneezing or coughing. A recent review of existing literature has analysed the time that SARS-Cov-2 remains infectious on various surfaces. Coronaviruses may remain viable for hours or even days; in some cases, human coronaviruses remained infectious for up to nine days. It follows, therefore, that regular touching of contaminated surfaces can lead to an increased risk of infection.2
MAY 2021
It has been shown with influenza A virus that a contact time of just five seconds can transfer 31.6% of the viral load onto the hands.3
Studies in various hospital environments have found links between hand and environmental contamination. Research evaluating the role of surface contamination in operating rooms found evidence that the environment may become contaminated with pathogens which may be transmitted to the hands of health staff and then onto patients.4 A review undertaken in intensive care units (ICU), found that inanimate surfaces and equipment (e.g. bedrails, stethoscopes, medical charts, ultrasound machine) may be contaminated by pathogens. This contamination is likely to result from the hands of healthcare staff or by direct patient shedding of pathogens. Unsurprisingly, a higher environmental contamination was found around infected patients than patients who were only colonised. Healthcare workers
not only contaminate their hands after direct patient contact but also after touching inanimate surfaces and equipment in the patient zone (defined as the patient and their immediate surroundings).5
Environmental contamination Viruses with pandemic potential including SARS-CoV, MERS-CoV, and influenza virus can survive on surfaces for extended periods of time, sometimes up to months. The survival of a virus depends on a number of environmental factors, including the strain variation, surface type, mode of deposition, temperature and relative humidity of the environment.1 Transmission of infectious diseases via an individual touching a contaminated surface has been shown to be possible.6 A recent report on the persistence of various coronaviruses on different surfaces ranged from 2 hours to 9 days.3 SARS-CoV-2 has been found to be more
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