More on MRSA and the new flu

Constant readers, I admit it: I am a bad blogger. The wave of news on the novel H1N1 (AKA the Virus Formerly Known as Swine) has been just overwhelming. Apologies for disappearing.

Out of the crashing surf, though, I picked up an interesting tidbit that speaks to our concerns about MRSA. Here's some background: If you have been following the swine flu story, you'll have noticed that one of the puzzles has been why the Mexican experience has been so different from the United States or from the other countries where this flu has appeared briefly. (North America so appears to be the only area in which there is sustained transmission.) Among the hypotheses:

• There is a difference in the medical care that victims are receiving.
• There is a statistical artifact: The serious cases are a tiny percentage of the mild cases, and the US has not seen enough cases to, probabilistically, experience significant serious cases yet.
• Or, corollary to the above: Mexico has many more cases than its surveillance systems have been able to count, and that is why we have seen that (unknown but presumably tiny) percentage that become serious cases appear there but nowhere else.

(For more on this, here's a CNN story from a few days ago, quoting me and people much more distinguished than me.)

But a commentary by a global-health expert raises another hypothesis, one that brings this outbreak around to our concerns: the possibility that the serious flu cases in Mexico are being complicated by secondary pneumonia caused by MRSA or other bacteria.

We've talked about this issue before (see this post about the importance of MRSA in a flu pandemic and this paper by, among others, Dr. Anthony Fauci, director of NIAID, and Jeff Taubenberger, PhD, co-discoverer of the virus of the 1918 flu). MRSA pneumonia secondary to flu infection is the etiology of the necrotizing pneumonia cases that kill children very quickly, and is the reason why I keep haranguing you regarding flu shots.

Is bacterial pneumonia playing a role in the current epidemic? It's too soon to tell; there is not sufficient clinical data. But it is an interesting speculation and one that we should keep in mind as this goes forward.