You’ll no doubt have seen a headline like this in some paper or other…

“MRSA Superbug kills 100 people in local hospital”

So what does that mean?

Well it might mean that 100 people died who were colonised with MRSA.

….or it might mean that 100 people who died of something or other, had an MRSA infection at some point during their admission.

…..or it might mean that 100 people died from documented MRSA infection.

…but it probably doesn’t mean that 100 people died specifically because their Staph aureus infection was resistant to beta-lactams.

Staph aureus is a virulent organism. Staph aureus bacteraemias, regardless of whether they are methicillin susceptible or resistant, have a mortality rate of approximately 20% depending on the cohort studied.

However trying to attribute mortality specifically to the Staph aureus being resistant is an almost impossible task.

So a more accurate headline might be “100 people in local hospital die from Staph aureus infection. An unknown proportion of these patients, probably quite small, died because the infecting bacterium was resistant to most beta-lactam antibiotics.”

Not much of a headline, nor would it sell many papers….

Michael