What types of substances if injested can cause pneumonia in a elderly man?

Hello, Anon.

Thank you for writing.

Germs called bacteria or viruses usually cause pneumonia. Pneumonia usually starts when you breathe the germs into your lungs. You may be more likely to get the disease after having a cold or the flu. These illnesses make it hard for your lungs to fight infection, so it is easier to get pneumonia.

Helena