MRSA and H1N1 "swine" flu - still not a lot of evidence

Hello again, constant readers. It's busy out there.

The CDC said Wednesday that new infections with the novel H1N1 virus (Formerly Known As Swine Flu) may be trending down. Nevertheless, there is still a lot of rumor and speculation out there regarding what role MRSA pneumonia may have played in serious cases.

The CDC commented on this in its May 19th press briefing:

Q: Is anybody looking for, and is anybody finding any evidence of, coinfection with MRSA?
A: We′re very interested in that question. As you know, the seasonal influenza in children we′ve been tracking pediatric deaths, and we have seen MRSA among seasonal flu cases in children at a higher rate than we had expected. MRSA is a big problem in the United States right now in terms of the community associated resistant staff or its infections. So far as we′ve been looking at the patients with the H1N1 virus, we don′t have evidence of coinfection. Not everybody has been tested for bacterial infections. But among the ones that have been tested, we aren′t seeing an important role for bacterial coinfection, including MRSA. I think this is an important issue for us to continue to follow, whether bacterial co-infections or bacterial pneumonias following the illness are featured. It′s a feature we′re interested in but haven′t seen this turn up yet.

We've talked a number of times before here about MRSA necrotizing pneumonia, and about the apparent importance of secondary bacterial infections to the death rates in prior flu pandemics.

But for anyone who needs a refresher, I recommend an excellent new paper by researchers at Emory University, published last week in the journal Lancet Infectious Diseases. It recounts the clinical course of two people who were treated at Atlanta's Grady Memorial Hospital for MRSA pneumonia. Both were adults, and both survived, but their courses were complicated; the clinicians note that they did not improve until they were given additional antibiotics aimed at shutting down MRSA's toxinproduction, a step that is not universally considered by doctors treating a MRSA patient.

The cite is: Hidron, AI et al. Emergence of community-acquired methicillin-resistant Staphylococcus aureus strain USA300 as a cause of necrotising community-acquired pneumonia. Lancet Infect Dis. 2009 Jun;9(6):384-92. The abstract is here.