Tuesday, August 19, 2008

Viral-Bacterial Copathogenesis



# 2241





Over the past couple of weeks we've heard a good deal about the role of secondary bacterial pneumonia in the 1918 Spanish Flu, and speculation on how that may affect us during the next influenza pandemic.



Some of these studies I've recently covered  are here, here, and here.



Today we have another study, this time in The Journal of Infectious Diseases, by Morens, Taubenberger, and Fauci that looks at the predominant role of bacterial pneumonia in the high death toll of 1918.



(highlighting and reparagraphing mine)




Predominant Role of Bacterial Pneumonia as a Cause of Death in Pandemic Influenza: Implications for Pandemic Influenza Preparedness

David M. Morens,

Jeffery K. Taubenberger, and

Anthony S. Fauci


National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland



Background.  Despite the availability of published data on 4 pandemics that have occurred over the past 120 years, there is little modern information on the causes of death associated with influenza pandemics.


Methods.  We examined relevant information from the most recent influenza pandemic that occurred during the era prior to the use of antibiotics, the 1918–1919 “Spanish flu” pandemic. We examined lung tissue sections obtained during 58 autopsies and reviewed pathologic and bacteriologic data from 109 published autopsy series that described 8398 individual autopsy investigations.


Results.  The postmortem samples we examined from people who died of influenza during 1918–1919 uniformly exhibited severe changes indicative of bacterial pneumonia. Bacteriologic and histopathologic results from published autopsy series clearly and consistently implicated secondary bacterial pneumonia caused by common upper respiratory–tract bacteria in most influenza fatalities.


Conclusions.  The majority of deaths in the 1918–1919 influenza pandemic likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.


Less substantial data from the subsequent 1957 and 1968 pandemics are consistent with these findings. If severe pandemic influenza is largely a problem of viral-bacterial copathogenesis, pandemic planning needs to go beyond addressing the viral cause alone (e.g., influenza vaccines and antiviral drugs).



Prevention, diagnosis, prophylaxis, and treatment of secondary bacterial pneumonia, as well as stockpiling of antibiotics and bacterial vaccines, should also be high priorities for pandemic planning.





The take away lesson from this and other studies we've seen over the past few weeks is that while antivirals may be valuable during a pandemic, they won't be enough by themselves.



Antibiotics will be needed to combat what are likely to be rampant secondary bacterial pneumonias.



Governments who have been thus far focusing on antiviral stockpiling must now consider expanding their stockpiles to include a wide variety of antibiotics as well.



Complicating matters greatly will be the wide variety of bacteria capable of causing secondary pneumonias.  



Typical community acquired pneumonias (CAP) are usually caused by Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis. While these strains generally respond well to penicillin's or other common antibiotics, drug resistant strains of S. pneumoniae are increasingly common.



Other, atypical pneumonias, and nosocomial infections such as caused by S. aureus, further complicate matters.   Once rarely seen outside of hospitals, S. aureus pneumonia has, in recent years, been occasionally seen in the community as well.  



Unlike antivirals, there is no one-pill-fixes-all solution here.  What works on one bacteria is often ineffective on another.



Undoubtedly, getting the right antibiotics into the hands of patients who will need them will be one of the biggest challenges facing the medical system during a pandemic crisis.  


ghanes14 said...

Nice post, it was informative and easy to read, many of the articles I find as big paragraphs making it hard to read.

I wrote an article about this on my site, if you want to view my post.

concerned about health restrictions said...

What I fail to understand, is why pneumonia vaccine is not more readily available to those who want it. In an age of increasing resistance to antibiotics, the vaccine as prevention seems to be a no-brainer. Recent tests have shown that survivors of the 1918 flu pandemic still have active antibodies in their bloodstreams. Perhaps one vaccination could provide immunity to many bacterial pneumonias for decades. To their credit, local hospitals in my state are now asking surgery patients if they have had both a flu shot and/or a pneumonia vaccine. Health departments need to get rid of the restrictions they currently have on obtaining the pneumonia vaccination. It was extremely difficult for members of my family to obtain one, even with a doctor's prescription request.(Two years ago.)