There was an organism that was identified in 1881 that some people call streptococcus pneumonia,

and some people call it streptococcus pneumoniae, and others call streptococcus pneumonia.

A lot of people are short in it to strep pneumo, and a lot of people call it pneumococcus.

And no matter what you prefer to call it, you will come to respect the pneumococcus.

Out of the more than 100 microbes that can cause pneumonia that we know about, it is the most common cause.

And it accounts for about two-thirds of bacteremia when bacteremia occurs from pneumonia.

And when the pneumococcus enters the bloodstream, causing bacteremia,

a seeding of different sites can occur, such as you can

get septic arthritis or endocarditis. So this metastatic infection can be very serious. Usually, when we

inhale the pneumocococcus, it's aerosolized and it just sets up a colonization in our nasofarangs.

That colonization usually occurs for about a month or two, and smokers are more likely to be colonized

than non-smokers. And if you've recently had antibiotics,

there's more of a chance that that colonization will consist of an antibiotic-resistant

Streptococcus pneumonia.

So why would some carriers of the pneumococcus get pneumonia and others not get it?

And I think part of the answer comes from the European Respiratory Journal in April 1st, 2005,

where there was a study where they looked at the relationship between the inoculum dose

of pneumococcus and pneumonia onset in rabbits.

There is a biologic balance that happens between bacteria and its hosts.

I already discussed in the first pneumonia podcast how our immune system is such an important factor,

but another huge factor is actually the inoculum, the actual amount of bacteria

that's getting into the lower respiratory tract that can overwhelm the host's defenses.

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