What is Pneumonia
•Pneumonia is an infection of the lungs
•Pneumonia results into inflammation (swelling of the lung tissue) and accumulation of fluid/pus in the alveoli (air sacs of the lungs).
•When fluids or pus accumulate in the alveoli, it becomes difficult to breathe. 
•Pneumonia can be caused by bacterial, viral or fungal infection. 
•Pneumonia can affect one or both lungs.
•The severity of the disease depends on its cause. Bacterial pneumonia is the most common and most severe type of the disease.

Types of Pneumonia
•Pneumonia can be classified by the pathogens that cause it or how it is acquired. 

  • Classification based on how Pneumonia is acquired

1. Community Acquired Pneumonia (CAP)
•Refers to pneumonia acquired outside of a hospital or medical institution setting


2. Hospital Acquired Pneumonia
•It is pneumonia acquired during a hospital stay.
•Most common cause is bacteria
It is normally more resistant to medication since the bacteria in most cases has evolved and are resistant to antibiotics.


3. Ventilator-associated Pneumonia
•It is the type of pneumonia acquired by people who use ventilators especially for patients in the ICU.
•Usually it is caused by the same pathogens that cause community acquired pneumonia and the resistant pathogens that cause hospital acquired pneumonia.


4. Aspiration Pneumonia
•Refers to pneumonia that is acquired by inhaling the pathogen from food, drink, or saliva.
•It can also result in people who have difficulty swallowing or those under sedation hence food or fluids find their way into their trachea and lungs.

 

  • Classification based on cause 

a). Bacterial Pneumonia
•It is the most severe form of pneumonia.
•The most common bacteria that causes pneumonia is Streptococcus pneumonia.
•Other bacteria that cause pneumonia are; Haemophilus influenzae, Mycoplasma pneumonia, Legionella pneumophila.
•Bacterial pathogens that cause pneumonia can be spread from person to person via respiratory droplets through coughing, sneezing and contact with infected surfaces.

b). Viral Pneumonia
•Common cause of most pneumonia infections.
•It manifests as mild infection and the individual can improve on their own without treatment (usually between 1 to 3 weeks).
•However, the person may develop bacterial pneumonia from the viral type hence worsening their condition.
•Several viruses may cause pneumonia, namely; influenza (Flu), rhinovirus (Common cold), adenovirus, coronavirus, SARS-CoV-2 (COVID-19), human parainfluenza virus (HPIV), chickenpox, Human metapneumovirus (HMPV), Respiratory syncytial virus (RSV).
•The viral pathogens can be spread from person to person via respiratory droplets. 

c). Fungal Pneumonia
•Usually occurs in people with weakened immune systems.
•Examples of fungi that can cause pneumonia are: Pneumocystis jirovecii, Cryptococcus species, Histoplasmosis species, Coccidioides species.
•Fungal pathogens are usually not spread from person to person like viruses and bacteria.