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Healthcare Associated Infections

Healthcare Associated Infections

Healthcare Associated Infections

The environment plays an important part in infection prevention and control and for this reason the evaluation of environmental cleanliness to be an integral part of any infection prevention and control program.

An important fact to remember is that just because the environment may appear ‘dirty’, this does not necessarily mean it poses an increased risk of infection for patients. Conversely, an environment that appears ‘clean’ may harbour microorganisms that are potentially harmful.

Healthcare associated infections (HAIs) have a major impact on the healthcare service and the population it serves. Large prevalence studies from several countries indicate that approximately 8 per cent of hospitalised patients will acquire an infection as a result of receiving healthcare. Within Australia there are an estimated 200,000 cases of HAI occurring each year.

HAIs affect the morbidity and mortality of patients and also result in adverse events such as prolonged length of stay in hospital. In addition to hospitals, HAIs affect patients in other healthcare settings such as long-term care facilities and general practice.

No single cause of, or quick fix for, the problem of HAIs exists at present. Evidence suggests that the issue needs to be tackled using a multi-faceted approach. Understanding the modes of transmission of infectious agents and applying basic principles to prevent infection are critical to reducing the occurrence of HAIs.

Some fundamental requirements for preventing infection in healthcare environments are cleanliness of hands and the environment and antimicrobial stewardship.

There are many methods of assessing environmental cleanliness and one of these is by using methods such as adenosine triphosphate (ATP) or microbial cultures. Hygienik uses this current method to ascertain levels for its evaluations.

One key element in infection prevention is environmental cleaning and a wide range of microorganisms can cause infections in a healthcare setting.

To understand how the environment may play a part in the occurrence of infections, it is important to think beyond the endpoint—the infected patient. For example, persons colonised with microorganisms can contaminate the environment. In turn, these microorganisms can be transferred to other sites, most commonly by the hands of healthcare workers, patients and visitors.

Microorganisms acquired from these sites may then be responsible for infection in other patients. In the past, the role of the inanimate hospital environment (e.g., surfaces and equipment) in the spread of HAIs has been regarded as controversial.  However, a large body of evidence now supports the notion that the environment does play a part in microorganism transmission and subsequent infection.

The potential for contamination of environmental surfaces to contribute to transmission of healthcare associated pathogens depends on a number of factors, including the:

• Ability of pathogens to remain viable on a variety of environmental surfaces

• Frequency with which organisms contaminate surfaces

• Handling frequency of surfaces and whether or not levels of contamination are sufficiently high to result in transmission to patients.

The time that pathogens remain viable in the environment varies considerably and depends upon the particular characteristics of the organism. Research has demonstrated that Staphylococcus aureus, the organism responsible for most HAIs in Australia, can remain virulent and capable of causing infection for at least 10 days after inoculation onto a dry surface.

The idea that microorganisms can survive for long periods in the environment has been supported by numerous studies. Unless adequate cleaning is undertaken, microorganisms in the healthcare environment may contaminate hands or uplifting air currents and be subsequently deposited onto a patient or surfaces near a patient. Sites considered to be ‘contact-touch sites’ are of particular importance. Microorganisms do not discriminate between environmental sites and when they persist on sites that are likely to be touched regularly, there is a risk of onward transmission to patients via healthcare workers’ hands.

Transmission cycle demonstrating the role of the environment.

Several studies have shown that persistence of microorganisms in the environment leads to an increased risk of acquiring an infection in a patient who is admitted to a room previously occupied by a patient colonised or infected with that particular organism. Environmental contamination in conjunction with colonisation pressure (i.e., the proportion of patients colonised with an organism) is thought to play a role in transmission of microorganisms. This concept has been demonstrated to explain the transmission of organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococcus (VRE) in the healthcare environment.

Microorganisms can be found on a large number of surfaces in the healthcare environment. Items in close proximity to the patient tend to be more heavily contaminated than those that are more remote. The greatest risk of acquiring microorganisms that result in infection has been suggested to arise from near-patient items such as bed rails and bedside tables, as contamination of these sites provides frequent opportunity for hands to touch and transfer organisms.

Frequently touched objects in the patient environment

Published studies demonstrating the importance of cleaning in outbreak scenarios underscore the likely role that environmental contamination plays in the transmission of HAIs. Multiple studies have shown that enhanced cleaning significantly decreases environmental contamination by a range of HAI pathogens.


• The healthcare environment plays a role in transmission of microorganisms that may cause infection and therefore potentially has a role in prevention.

• Near-patient (frequently touched) objects are often contaminated with potentially pathogenic microorganisms and therefore pose the greatest risk for the transfer of pathogens.

• The risk of acquiring a specific organism is increased if a patient is admitted to a room previously occupied by a patient who had been colonised or infected with that organism.

• Environmental cleaning reduces environmental contamination thus can reduce the risk of transmission of infection.