Are CA-MRSA more virulent than HA-MRSA?

Community-associated MRSA (CA-MRSA) are characterised by the ability to cause infections – and sometimes serious invasive infections – in previously healthy individuals without healthcare contact. We don’t see this clinical manifestation in healthcare-associated MRSA (HA-MRSA), so it’s is logical to conclude that CA-MRSA are somehow more virulent than HA-MRSA. However, a recent study published in the Journal of Medical Microbiology shows that CA-MRSA strains were no more virulent than HA-MRSA strains in a battery of laboratory tests. This suggests that CA-MRSA’s ability to cause infections in healthy individuals without healthcare contact has more to do with transmissibility than virulence. And this explains the curious phenomenon that CA-MRSA seem to cause the same spectrum of disease as HA-MRSA when they infiltrate a healthcare setting.

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