New Research Helps Explain the Rise in Hospital MRSA Infections

New research by scientists by the University of Warwick may explain why methicillin-resistant Staphylococcus aureus (MRSA) infections are so difficult to control in hospitals. MRSA is a major cause of invasive and sometimes deadly disease in hospitalised patients. Currently, attempts to prevent spread of these infections include isolating infected patients and increasing staff hygiene measures such as handwashing. However, these attempts have met with limited success.

A new mathematical model helps explain why infections represent a serious threat and why attempts to control MRSA, the so-called ‘superbug’, have failed or met limited success. Scientists explored the conditions under which isolation policies can control MRSA transmission, both by preventing an endemic state and eradicating MRSA where it is already endemic.

The mathematical model shows how the rising drug resistant strains of MRSA may fail depending on the timing of intervention and the levels of resource provision. If resources, such as the isolation of patients and in dedication isolation units (IUs), do not scale with MRSA, prevalence isolation policies can fail catastrophically.

Dr Graham Medley, from the University of Warwick, said: “The research reveals that measures able to control even short-term outbreaks could fail in the long-term and result in gradually increasing MRSA levels due to small but rising MRSA levels in the community. The report suggests that control measures may also fail because hospital resources, such as the capacity to isolate patients, are insufficient to cope with brief spikes in MRSA levels.”

Once hospital defences have been overcome, the authors suggest that recovery is almost impossible without the benefit of further resources.

“Methicillin-resistant Staphylococcus aureus in hospitals and the community: stealth dynamics and control catastrophes” is published in the Proceeding of the National Academy of Sciences of the United Stated (PNAS), June 21st 2004