mrsa infection controlMRSA infection control is a growing challenge in general hospital infection control.  As preventing MRSA infection requires a very clear understanding of how MRSA is transmitted from patient to patient. There's now some evidence that airborne MRSA is contributing to the problem, which will have implications for infection control strategies as a whole.

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium which is not treatable by beta-lactam antibiotics, including methicillin but also flucloxacillin and amoxicillin. It is very similar in all other respects to 'ordinary' (or methicillin sensitive) S.aureus. These bacteria normally live on the skin or on the mucous membranes of the nose.  Around 30% of the population is colonised, as it's called, by S.aureus in this way. In around 2% of the population, the bugs are MRSA. Colonisation in itself does not harm your health, but it is a risk factor for infection, which occurs when the bacteria enter the body, usually through an open wound or sore, or perhaps through the insertion of a medical device like a catheter. An ordinary S.aureus infection should not be a problem – because you can be treated with antibiotics, including the beta-lactams. If it is MRSA, then you may be in trouble – particularly if you have weakened immunity (the elderly, hospital patients with certain conditions like AIDS, cancer, or those in intensive care). In such situations, MRSA can cause life-threatening blood infection (septicaemia) which can spread to vital organs.

In England, MRSA infection control has been under surveillance in NHS Trusts since 2001 (this means they have to report figures to the Health Protection Agency). This shows that rates of MRSA infections have been decreasing in recent years but obviously, there's still a need for strict and continuing airborne infection control in our hospitals.

So how is MRSA transmitted? Contact with a person colonised with MRSA is one way of spreading the infection. According to the Centers for Disease Control and Prevention, healthcare personnel may spread MRSA by touching a colonised patient then touching another patient without first washing their hands (that's why it's always OK to check with a doctor or nurse whether their hands are clean before they touch you).

Another way in which you can contract (and/or spread) MRSA in the hospital is by touching a contaminated surface.  There are many items in a hospital that have been shown to harbour MRSA, including:

  • Door handles
  • Curtains
  • Beds
  • Bedside tables
  • Pens
  • Doctors' ties
  • Computers
  • Call buttons
  • Door handles
  • Bedclothes
  • Floors

How do all these items and surfaces become contaminated with MRSA? A colonised person (or someone who has been in contact with them) may have touched them. Or the MRSA may have been spread through the air and settled on the item or surface. Airborne transmission of MRSA has been suggested by a number of air sampling studies. For instance, air sampling before and after bed making showed that MRSA levels remain higher for up to 15 minutes after completion of the task.

It's clear that it must be important to wipe MRSA off a contaminated surface. But what we don't yet know is the most effective way of doing this. You can't see MRSA, so it could still be lurking on an apparently clean surface. Maybe one element in the MRSA infection control should be to stop airborne MRSA from settling on a surface in the first place. Researchers at Nottingham City Hospital carried out a study that shows the use of the portable IQAir Cleanroom H13 air purifier reduced MRSA contamination in hospital isolation rooms occupied by patients known to be heavy MRSA dispersers. They concluded that a portable air purifier could be a relatively cost-effective way of enhancing MRSA control in hospitals.