Patient and Community Problem 5
Learning Issue: Pathophysiology of Pneumonia
What is pneumonia?
Pneumonia is a form of acute respiratory infection that affects the lungs. The lungs are made up of
small air sacs called alveoli, which fill with air when a healthy person breathes. When an individual
has pneumonia, the alveoli (air sacs) becomes inflamed due to an infection and are filled with fluid
or pus, causing cough with phlegm or pus, fever, chills, and limiting oxygen intake causing difficulty
in breathing. Pneumonia can affect anyone, but the two age groups at highest risk are, children who
are 2 years old or younger, and people who are age 65 or older. The infection varies in seriousness
from being mild to severe and even life threatening.
Categories of pneumonia:
• Community-acquired pneumonia-people getting pneumonia outside of hospitals or other
health care facilities.
• Hospital-acquired pneumonia-people getting pneumonia when they are already
hospitalised for something else. Hospital-acquired pneumonia can be serious because the
bacteria causing it may be more resistant to antibiotics and because the people who get it
are already sick. People who breathe through ventilators often used in intensive care unit
(ICU) are at higher risk of this type of pneumonia.
• Aspiration pneumonia- when food or drinks travel down the airway, normally one gags
and coughs it out, but if your reflexes of gagging is compromised due to drugs, alcohol, brain
injuries or swallowing issues, the food particle or drink taken into the airway remains there.
The microbes from these food particles can then infect the lungs causing pneumonia.
What causes pneumonia?
Pneumonia is caused by several infectious agents (pathogens), including viruses, bacteria and fungi.
The most common are bacteria and viruses in the air that we breathe.
• Streptococcus pneumonia is the most common cause of bacterial pneumonia in children.
• Haemophilus influenzae type b (Hib) is the second most common cause of bacterial pneumonia.
• Respiratory syncytial virus is the common viral cause of pneumonia.
• In infants infected with HIV, Pneumocystis jiroveci is one of the most common causes of
pneumonia, responsible for at least one quarter of all pneumonia deaths in HIV-infected infants.
When breathing in air, we constantly breathe in microbes/germs as well, but we are usually
pretty good at protecting ourselves through coughing, in which a mucociliay escalator
(defence mechanism) lines the entire airway and moves out larger bacteria and
macrophages that are nestled deep inside the alveoli and are ready to destroy anything that
lands there. Sometimes a microbe might succeed in colonising the bronchioles or alveoli.
They multiply and invade the lung tissue (alveoli) creating an inflammatory response. When
this happens, the blood vessels dilate and the blood vessel walls actually separate and
become leaky (causing capillary leak). This allows the white blood cells to move out from the
blood vessels and into the lungs to fight the invading pathogens. All of those white blood
cells and dead pathogens causes a lot of exudate (fluid) or debri build up inside the lungs
and this causes obstruction in the lungs which results in reduced gas exchange.
Mode of Transmission of pneumonia:
Pneumonia can be spread in several ways. The viruses and bacteria that are commonly
found in a child’s nose or throat can infect the lungs if they are inhaled. They may also
spread via air-borne droplets from a cough or sneeze. In addition, pneumonia may spread
through blood, especially during and shortly after birth
Risk Factors of pneumonia:
• Children whose immune systems are compromised are at higher risk of developing
pneumonia (a child’s immune system may be weakened by malnutrition/undernourishment,
especially in infants who are not exclusively breastfeed).
• Pre-existing illnesses, such as symptomatic HIV infections and measles, also increase a
child’s risk of contracting pneumonia.
• Environmental factors including:
- indoor air pollution caused by cooking and heating with biomass fuels (wood or dung)
- living in crowded homes
- parental smoking
Signs and Symptoms of pneumonia:
Symptoms may vary for each child depending on what is causing the pneumonia.
Pneumonia caused by a virus is often less severe than when caused by bacteria and usually
start out as flu with symptoms including:
• fast, difficult breathing
• chills and fussiness
• headache
• wheezing (common viral infections)
Cases of bacterial pneumonia tend to happen suddenly with symptoms such as:
• cough that produces mucus
• tiredness (fatigue)
• chest pains
• diarrhoea/vomiting
• fever
• loss of appetite.
How to diagnose pneumonia:
Diagnosis is generally based on a physical exam and several other tests, which may include
blood tests, chest X-ray, chest CT scan, sputum culture and so on.
Treatment:
Depends on the type and severity of the pneumonia whether its bacterial or viral
pneumonia. The patient may be given antibiotics (amoxicillin dispersible tablets), cough
suppressants, and pain medications. Hospitalisation is recommended only for severe cases
of pneumonia.
Prevention:
Pneumonia can be prevented by immunization (vaccine), adequate nutrition is key to
improving children’s natural defences, and by addressing environmental factors such as
indoor pollution and encourage good hygiene in crowded homes.
Reference
 https://www.who.int/news-room/fact-sheets/detail/pneumonia
 https://www.mayoclinic.org/diseases-conditions/pneumonia/symptoms-causes/syc20354204
 https://www.webmd.com/children/what-to-know-about-pneumonia-in-children