Classifying the Different Types of Pneumonia

types of pneumonia

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  • Pneumonia cases can differ from each other because of many other factors that come into play
  • One way to classify a pneumonia case is to know where you got infected with the pneumonia-causing bacteria, virus or germ

Did you know that there are 30 or more known causes of pneumonia?1 Because of this, pneumonia cases can differ from each other because of many other factors that come into play.

Types of Pneumonia According to the Illness-Causing Agent

A factor that has to be taken into consideration is the main agent that causes the infection. These are just some of the main groups of pneumonia based on what ignites the disease:2

Bacterial pneumonia: commonly caused by bacteria strains such as Streptococcus pneumoniae, Chlamydophila pneumonia or Legionella pneumophila.3

This affects people of all ages,4 leading to a weakened ability of the body to exchange oxygen and carbon dioxide, breathlessness and pain when you try to take in oxygen.5

Bacterial pneumonia cases can be mild or severe, depending on the strength of the bacteria strain and how long until the disease is diagnosed and treated.6

Viral pneumonia: triggered by viruses such as influenza, chickenpox, adenoviruses or respiratory syncytial virus.7 You can catch viral pneumonia via coughing, sneezing or touching an object that was contaminated by an infected person.

A patient with viral pneumonia doesn’t just have swollen lungs, but blocked oxygen flow as well.8

Viral pneumonia is said to be responsible for one-third of all pneumonia cases. People who have this type of pneumonia are also most likely to get bacterial pneumonia.9

Mycoplasma pneumonia: generated by Mycoplasma pneumoniae, an “atypical bacterium” that’s considered to be one of the smallest agents that affect humans.10,11 This is why this type of pneumonia is also called atypical or walking pneumonia.12

Mycoplasma pneumonia affects people of all age groups,13 but it’s more common among people who are less than 40 years old.14 The disease can be transferred easily via respiratory fluids, leading to regular epidemics.15

People who have this disease exhibit different symptoms and physical signs, but overall they have mild and widespread pneumonia16 or dry cough.17 Most mycoplasma pneumonia cases are mild.18

Aspiration pneumonia: infections or inhalation of food, liquid, gases or dust lead to this type of pneumonia.19 This illness goes by other names, such as necrotizing pneumonia, anaerobic pneumonia, aspiration pneumonitis, and aspiration of vomitus.20 People with aspiration pneumonia have inflammation minus the bacterial infection. Unfortunately, aspiration pneumonia can be difficult to treat on some occasions because people who usually acquire this disease are already sick to begin with.21

Fungal pneumonia: produced by various endemic or opportunistic fungi. This causes fungal infections, such as histoplasmosis, coccidioidomycosis, and blastomycosis that occur after inhaling spores or conidia or reactivating a latent infection. It has to be noted that fungal pneumonia cases are quite difficult to diagnose.22

Although cases of fungal pneumonia are not so common in the U.S.,23 they’re prevalent in Mexico and other South American countries, as well as African countries.24

Types of Pneumonia According to Where the Infection Was Acquired

Another way to classify a pneumonia case is to know where you got infected with the pneumonia-causing bacteria, virus or germ. There are three types of pneumonia that are determined by the place where you acquired the disease:25

Community-acquired pneumonia (CAP): happens after acquiring a common viral infection, such as the flu. Patients who have CAP got the disease outside of hospitals or other health care settings, such as at school or at work,26 and are consequently infected with germs that are found in the mouth, nose or throat while they are sleeping.27

Community-acquired pneumonia is the most common type of pneumonia, with majority of the cases occurring during winter. According to the National Heart, Lung, and Blood Institute, around 4 million Americans are affected every year, with 1 out of 5 people with CAP requiring hospitalization.28

Hospital-acquired pneumonia (HAP): occurs when people are infected when they’re admitted to a hospital for another illness. HAP tends to be more dangerous compared to community-acquired pneumonia because you’re already sick when you’re infected with HAP. Your risk for HAP even rises when you already use a ventilator. Plus, hospitals are usually hotbeds for antibiotic-resistant germs.29

Health care-associated pneumonia: refers to an infection in other health care settings such as nursing homes, dialysis centers and outpatient clinic.30

Specific Types of Pneumonia You Should Watch Out For

There are other types of pneumonia that don’t fall under the categories listed above. Regardless, it’s still important to be vigilant and consult a physician or health expert when you notice symptoms of these infections, since some diseases might lead to further harm.

Pneumococcal pneumonia: this is caused by bacteria (such as Streptococcus pneumoniae), viruses or fungi. This disease is common among children under 5 years old or adults 65 years old and above. Pneumococcal pneumonia infects the upper respiratory tract and can spread to the nervous system, lungs, ears, or blood if not treated immediately.31

Bronchial pneumonia: a class of pneumonia that affects both the lungs and the bronchi.32 The Streptococcus pneumonia bacteria strain is the usual origin of this disease, but it can also be triggered by other strains such as Staphylococcus aureus, Haemophilus influenza or Klebsiella pneumoniae.33

Lobar pneumonia: another disease caused by the Streptococcus pneumoniae bacteria strain wherein there is an infection in one lobe (or area) of the lung.34

Legionella pneumonia: also known as Legionnaires’ disease, this is caused by the legionella bacterium strain. Patients affected by Legionella pneumonia inhale the bacteria, which is why this severe type of pneumonia is common among older adults, smokers and immunocompromised people.35

Bilateral pneumonia: this is caused by a bacterial, viral or fungal infection that affects both lungs. It’s also known as double pneumonia, and patients have difficulty breathing and show traces of fluids in the lungs. The risk for being infected with this disease is high among older people who have difficulty swallowing, alcoholics, and recreational drug users.36

Eosinophilic pneumonia: also known as acute eosinophilic pneumonia (AEP). This is a rare condition wherein eosinophils, a type of white blood cell that’s part of your immune system, increase rapidly and accumulate in your lungs. Eosinophils form in order to combat allergens, inflammation or infection. The cause of the disease is yet to be determined, although researchers are looking into the link between environmental factors and the development of the disorder.37

Lipoid pneumonia: lipoid pneumonia is a rare disease wherein oily and fatty substances enter the lungs.38,39 According to the Journal of General Internal Medicine, lipoid pneumonia is often caused by inhalation, aspiration or even ingestion of fatty substances such as petroleum jelly, mineral oils, nasal drops and olive oil.40

Hypostatic pneumonia: this disease manifests at the base of the chest cavity, when the lower portions of the lungs are not able to expand properly because the patient is either inactive or immobile.41,42 Hypostatic pneumonia is common among elderly and/or debilitated people.43

Interstitial pneumonia: considered to be rare, this happens when there’s an inflammation of the “mesh-like” walls of the alveoli (or air sacs) in your lungs, and as a result, the small air sacs in the lungs become separated. There might be an inflammation of the pleura (a thin cover that shields the lungs and its individual lobes) as well.44


Pneumonia: Introduction

What Is Pneumonia?

Is Pneumonia Contagious?

Pneumonia Duration

Pneumonia Types

Pneumonia Causes

Pneumonia Symptoms

Pneumonia Treatment

Pneumonia In Children

Pneumonia In Elderly

Bronchitis vs Pneumonia

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