many doctors believe that aspiration (having stuff go down into the lungs) causes anaerobic pneumonia
The NIH seems to believe that, too:
Aspiration pneumonia is inflammation of the lungs and airways to the lungs (bronchial tubes) from breathing in foreign material.
Twist: the myth was the professor believing that to be a myth!
Also, it is indeed possible for contaminants to create a lung abscess with anaerobic conditions within. No idea regarding the frequency of such.
Lastly, not all of the alveolar tree is ventilated at all times, there are non-ventilated parts that do not even get perfusion (Euler-Liljestrand mechanism). Those could also provide a breeding ground for anaerobes.
Today I Learned in Medical School:
Doctors have medical myths too! According to my prof, many doctors believe that aspiration (having stuff go down into the lungs) causes anaerobic pneumonia, but that is rarely the case. He says that myth is often taught resident-to-student, but it isn’t actually backed up by any research, and isn’t true. The kicker - if the doctor would stop to think about it, it should jump out as unintuitive – it would take some serious changes inside the *lung* to make an *anaerobic* infection – an infection of bacteria that thrive in areas with no oxygen. In reality it takes frequent aspirations over a long period of time to block off an area of the lungs.
I think the moral of this story (though this just may be preaching to the choir here at LW) – all people, be they doctors or kindergarteners, don’t usually check facts they’re taught, especially when being taught by an authoritative teacher. Unless they’re lead to discover/derive a fact themselves, they usually assimilate it into their network of beliefs as a brute fact – “carbon has four valence electrons,” “don’t end a sentence with a preposition,” “in 1492 Columbus discovered America.”
Now, you frequently don’t have enough time to “learn it the hard way” or derive an answer yourself. If I had to read every single research publication that populated the facts in my textbooks, I might not ever graduate. However, it is important to remember that you’ve taken shortcuts for most of your education (and religion/lack thereof, and life in general) – and if some fact ever later strikes you as being odd, look into it. Otherwise, we’re just playing the telephone game.