Bacterial vs. Viral Pneumonia

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Have you heard of pneumonia? Did you know it could be caused by many different things? Two of them are bacteria and viruses. Find out what kinds may lead to pneumonia thanks to this lesson.

A Deadly Disease

Did you know that the largest infectious cause of death in children throughout the world is a one word disease that you've almost certainly heard of? It killed nearly 1,000,000 children under the age of 5 in 2015. Despite being a one word disease, it can be caused by numerous things, including viruses and bacteria. It's called pneumonia. Let's take a closer look at it.

What is Pneumonia?

Pneumonia can actually be defined in many ways. If we break down the word parts we get pneumon-, which refers to the lungs in this case and -ia a state or condition, usually abnormal. So the word literally means an abnormal condition of the lungs.

Another way to define pneumonia is a condition that's marked by inflammation of the lungs due to any number of causes, including infectious and non-infectious causes. In common usage, however, pneumonia is simply known as a lung infection and this lesson is going to focus on this lay definition. The lungs can be infected by viruses, bacteria, fungi, and parasites. Most often, however, it is viruses and bacteria that lead to the various infectious types of pneumonia.

What is Viral Pneumonia?

Viral pneumonia is caused by viruses, which are extremely small infectious microorganisms. Viruses are considered by many in the scientific community to be non-living entities that only come alive when they enter our body. And come alive they do. They cause us everything from the cold to the flu. Speaking of that, it turns out that the viruses that cause the cold and flu can lead to pneumonia.

Adenovirus can cause the common cold and pneumonia. A virus that sometime causes cold-like symptoms, called respiratory syncytial virus, can do so as well. The influenza viruses causes the flu and may lead to pneumonia as well. A virus similar to influenza, called parainfluenza, is another agent of pneumonia. The list of viruses that can lead to pneumonia or cause pneumonia directly is long. However, the four we just went over are some of the more common ones.

The flu virus

What is Bacterial Pneumonia?

Not to be outdone, bacteria are also quite famous for causing pneumonia. Actually, a virus may play a part in this. See, if you get infected with a virus, your body's fight against this virus may stretch your immune system (your defense force) so thin that you'll get a secondary bacterial infection. Basically, the bacteria take advantage of the fact that you're weak.

Like viral pneumonia, the list of bacteria that causes bacterial pneumonia is long. The most common cause is called, fittingly enough, Streptococcus pneumoniae. The second most common cause is known as Haemophilus influenzae, particularly in people with COPD (chronic obstructive pulmonary disease). Next, Klebsiella pneumoniae likes to strike those that have a serious disease, like diabetes. Finally, Staphylococcus aureus causes pneumonia in high-risk groups like drug abusers. It's famous because it is the cause of Methicillin-resistant Staphylococcus aureus (MRSA), a very dangerous infection that is resistant to most antibiotics. Antibiotics are drugs that kill bacteria.

Streptococcus pneumoniae bacteria
Streptococcus pneumoniae

Lesson Summary

Bacteria and viruses are two common causes of pneumonia, which is more simply a lung infection.

Common causes of viral pneumonia are the:

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