Pneumonia – Causes, Symptoms and Treatment

Pneumonia – Causes, Symptoms and Treatment


Pneumonia is a lung infection that causes the air sacs in one or both lungs to become inflamed. Cough with phlegm or pus, fever, chills, and trouble breathing can occur when the air sacs fill with fluid or pus (purulent material). Pneumonia can be caused by a variety of species, including bacteria, viruses, and fungus.

Pneumonia, both viral and bacterial, is contagious. This means that they can be passed from person to person by inhaling airborne droplets from a sneeze or cough. These types of pneumonia can also be contracted by coming into touch with surfaces or items contaminated with pneumonia-causing bacteria or viruses. Fungal pneumonia can be contracted from the environment. It does not pass from one person to the next.

Pneumonia is further divided into categories based on how or where it was acquired:

  1. Hospital-acquired pneumonia (HAP) – This kind of bacterial pneumonia is contracted while in the hospital. Because the bacteria implicated may be more resistant to drugs than other varieties, it can be more dangerous.
  2. Community-acquired pneumonia (CAP) – Pneumonia obtained outside of a medical or institutional setting is referred to as this.
  3. Ventilator-associated pneumonia (VAP) – VAP is a type of pneumonia that affects patients who use a ventilator.
  4. Aspiration pneumonia – Aspiration pneumonia is caused by inhaling microorganisms from food, drink, or saliva into your lungs. If you have a swallowing difficulty or are excessively sedated from the use of medications, alcohol, or other drugs, it’s more likely to happen.

Walking pneumonia

Walking pneumonia is a type of pneumonia that is less severe. Walking pneumonia patients may be unaware that they have the disease. It’s possible that their symptoms are more akin to a minor respiratory illness than pneumonia. Walking pneumonia, on the other hand, may necessitate a lengthier recuperation time.

The following are some of the symptoms of walking pneumonia:

  • a low-grade fever
  • a dry cough that lasts more than a week 
  • chills
  • Breathing problems
  • chest discomfort
  • decreased appetite

Pneumonia is commonly caused by viruses and bacteria such as Streptococcus pneumoniae and Haemophilus influenzae. Walking pneumonia, on the other hand, is most usually caused by the bacteria Mycoplasma pneumoniae.

Stages of pneumonia

Pneumonia can be characterized according to the part of the lungs it affects:

  • Bronchopneumonia – Bronchopneumonia can damage portions of your lungs on both sides. It’s usually seen at or around your bronchi. The tubes that connect your windpipe to your lungs are known as bronchioles.
  • Lobar pneumonia – One or more lobes of your lungs are affected by lobar pneumonia. Lungs are divided into lobes, which are distinct regions of the lung. Based on how far illness has progressed, lobar pneumonia can be categorized into four stages:
    • Congestion – The lungs appear thick and clogged. Infectious organisms have accumulated in the fluid that has accumulated in the air sacs.
    • Red Hepatization – The fluid has been contaminated with red blood cells and immune cells. The lungs appear red and solid as a result of this.
    • Gray hepatization – It is a term used to describe the process of a person’ Red blood cells are starting to break down, but immune cells are still present. The hue of red blood cells changes from red to grey as they break down.
    • Resolution – The infection is being cleared by immune cells. A productive cough aids in the ejection of any remaining liquid from the lungs.

Pneumonia Causes

Pneumonia occurs when bacteria enter the lungs and produce an illness. The immune system’s response to the infection causes inflammation of the air sacs in the lungs (alveoli). The air sacs might eventually fill up with pus and liquids as a result of the inflammation, resulting in pneumonia symptoms. Pneumonia can be caused by a variety of infectious organisms, including bacteria, viruses, and fungus.

Bacterial pneumonia

Streptococcus pneumoniae is the most prevalent cause of bacterial pneumonia. Other factors to consider are:

  • Mycoplasma pneumoniae is a bacterium that causes pneumonia.
  • Haemophilus influenza is an infectious disease caused by the bacteria Haemophilus influenza
  • Legionella pneumophila is a kind of Legionella bacteria.

Viral pneumonia

Pneumonia is frequently caused by respiratory viruses. Pneumonia can be caused by a variety of viral infections, including:

  • Influenza pandemic (flu)
  • RSV (respiratory syncytial virus) is a virus that causes respiratory (RSV)
  • Viruses that cause rhinorrhea (common cold)
  • Infection with the human parainfluenza virus (HPIV).
  • Infection with the human metapneumovirus (HMPV)
  • Measles
  • Chickenpox is a disease caused by chickens (varicella-zoster virus)
  • Infection with the adenovirus or coronavirus

Despite the similarities in symptoms between viral and bacterial pneumonia, viral pneumonia is frequently milder. Without treatment, it can improve in 1 to 3 weeks. People with viral pneumonia are at risk of acquiring bacterial pneumonia, according to the National Heart, Lung, and Blood Institute.

Fungal pneumonia

Pneumonia can be caused by fungi found in soil or bird droppings. People with compromised immune systems are more likely to develop pneumonia as a result of them. Fungi that might cause pneumonia include the following:

  • Pneumocystis jirovecii 
  • Species of Cryptococcus
  • Species of histoplasmosis

The less common causes of bacterial pneumonia are:

  • Haemophilus influenza type B (Hib) causes pneumonia in children less than 5 years of age. It can also cause other infections like meningitis, and ear infections. However, due to Hib vaccinations, these infections are now less common.
  • Moraxella catarrhalis is seen as a part of the harmless bacteria of our mouth and throat. But it can cause pneumonia in children and adults with other lung diseases like Asthma and COPD. Usually, it causes ear infections and sinusitis in children.
  • Staphylococcus aureus pneumonia is more common in hospitalized patients or following the viral flu. These infections can become severe and difficult to treat as they are resistant to multiple antibiotics.
  • Klebsiella pneumonia can cause pneumonia in hospitalized patients on a ventilator. It can also cause pneumonia in alcoholics.
  • Streptococcus agalactiae (Group B strep) is a bacteria seen in the female vagina. They can be passed from a pregnant woman to her baby during childbirth and cause severe infections in the newborns. They can also cause infections in the elderly who have diabetes or neurological disease.
  • Pseudomonas aeruginosa can cause pneumonia in individuals with decreased lung function like cystic fibrosis, individuals with low immunity and hospitalized individuals.

Based on the geographical location of the individual, the type of bacteria causing the infection could vary. In such cases, travelers and tourists who migrate from certain countries may be exposed to bacteria types that are less common in their own geographical location. In some cases, a person may be exposed and become vulnerable to a rare type of bacterial pneumonia due to his weakened immune system or an underlying health condition.


Symptoms of pneumonia vary based on the age of the affected individual, his or her health condition and the type of microorganism that is causing the infection.

In newborn babies, the common symptoms are wheezing, grunting, breathing rapidly, irritability and lethargic behavior. Mild symptoms of pneumonia resemble that of a regular cold or flu but they tend to last longer.

Common symptoms of pneumonia include:

Pneumonia can progress and become life-threatening in some individuals. And hence, with medical assistance must be initiated as early as possible.

Risk Factors

Pneumonia can occur in anyone but the following individuals are at highest risk.

  • Children below 2 years of age
  • Adults over 65 years of age
  • Hospitalized individuals: Hospitalisation increases the risk of exposure to micro-organisms, especially in those who require a ventilator.
  • Presence of chronic diseases: Having chronic diseases like asthma, chronic obstructive pulmonary disease (COPD), or heart diseases can make an individual more vulnerable to pneumonia.
  • Smoking: Smoking usually results in the damage of the body’s natural defense systems against bacteria and viruses, making individuals more prone to infections like pneumonia.
  • Weak immune system: People with severe underlying health conditions like HIV/AIDS, those who have had an organ transplant, those on chemotherapy regimen or long-term usage of steroids are at higher risk for pneumonia.


Diagnostic tests for pneumonia detect the presence of pneumonia, the microorganism causing the infection and the extent of damage to the lungs. Diagnosis is also essential to limit the spread of infection, to understand its severity and also as a guide to the treatment that is to be given.

Common infectious organisms are usually difficult to be identified, and therefore the medical history or the patient, identification of common agents in the community and the patient’s clinical presentation are taken into consideration. In cases where symptoms do not resolve after a primary treatment, additional testing may be performed to diagnose and identify less common causes of pneumonia.

Based on the symptoms displayed by the person and his health status, various laboratory tests may be performed for accurate diagnosis. Commonly prescribed diagnostic tests that can be done in a laboratory include:

  • Complete Blood Count (CBC): The presence of infection may be detected by the number of white blood cells or WBC present in the blood.
  • Basic Metabolic Panel (BMP): Tests for sodium, potassium and other elements in order to determine the severity of the infection.
  • Arterial Blood Gases or ABG: This test measures pH and the amount of oxygen and carbon dioxide in the blood. This is an indication of lung function.

In order to diagnose the presence of bacteria, the common tests prescribed are:

  1. Sputum Culture/Gram Stain: Primary test to identify the bacterial cause of pneumonia. Culture can also identify the antibiotics to which the bacterial agent is susceptible.
  2. AFB Smear and Culture: Tuberculosis can also present like pneumonia. This test is required to identify tuberculosis bacteria in the lungs.
  3. Blood Culture: This test is done when it is suspected that infection has spread from lungs to blood or from blood to the lungs.
  4. Pleural Fluid Analysis: Sometimes fluid collects around the lungs between its coverings. This fluid is tested for identifying the cause of pneumonia.
  5. Special Test:  Special tests can identify specific causes of pneumonia. These include those which cannot be cultured Examples are
    1. Mycoplasma
    2. Legionella
    3. Influenza Tests
    4. RSV Testing
    5. Fungal Tests

Chest X-ray: Chest X-ray detects and evaluates the severity of a lung infection. When a patient has pneumonia, the affected lung may show up on the chest X-ray as patches.

Computed Tomography Scan (CT Scan)  is used to detect and evaluate the structure of the lung and the changes due to pneumonia.

Pneumonia Treatment

Treatment for pneumonia varies depending on the type and severity of the infection. Various medications for pneumonia include:

  • Antibiotics: These medicines work on the bacteria. Antibiotics are prescribed by the doctor based on the type of bacteria causing pneumonia. If the symptoms fail to ease, replacement of antibiotics is done.
  • Cough Medicine: Severe coughing can be troublesome for patients. Cough medication reduces cough and helps the patient rest. A cough is sometimes required to remove fluid from the lungs. in such cases, the low dose of cough medicine might be reduced.
  • Antipyeretics: When a person is experiencing discomfort due to fever and pain during the infection, medications to reduce fever and pain, like paracetamol, are prescribed.
  • Admission into the hospital may be required in severe infections, individual over 65 years of age, or if they have variations in blood pressure, damage to kidney function, rapid breathing, confusion, low/high heart rate and breathing difficulties.
  • Children may require hospitalization if they are younger than 2 months of age or if they are lethargic, having a high fever and experiencing breathing difficulties. If the child appears dehydrated, it is also a sign to get them hospitalized.
  • For those who have been infected with pneumonia, getting plenty of rest, staying hydrated and taking medicines as prescribed can help decrease the risk of complications and aid in speedy recovery.

Pneumonia Prevention

Some practices can help prevent pneumonia and serious illness.

  • Vaccination: The most common types of pneumonia can be prevented by vaccination. The vaccine available include
  • Pneumococcal Vaccine: This vaccine protects the individual from serious infections of Streptococcus pneumonia. Two types of pneumococcal vaccine are available. These are the pneumococcal polysaccharide vaccine(PPSV23) and pneumococcal conjugate vaccine (PCV 13).
  • Hemophilus influenza vaccine or Hib vaccine prevents pneumonia due to Hemophilus influenza.
  • Other relevant vaccines include influenza vaccine, chicken pox vaccine, MMR

Some other preventive measures include:

  • Thorough and frequent washing of hands
  •  Covering of the nose while sneezing
  • Cleaning and disinfecting surfaces like door knobs, handles, keyboards, remotes, mobile phones and other items that are frequently touched by hands.
  • Avoiding touching face, eyes, nose and mouth without washing hands
  • Avoiding close contact with those who have cold and cough respiratory infections
  • Stop smoking


Among the potential complications are:

  • Chronic conditions – If you have certain pre-existing medical disorders, pneumonia may exacerbate them. Congestive heart failure and emphysema are two of these disorders. Pneumonia raises the risk of having a heart attack in some people.
  • Bacteria – Bacteria from a pneumonia infection can enter your bloodstream and cause illness. This can result in dangerously low blood pressure, septic shock, and organ failure in some situations.
  • Lung abscesses – These are pus-filled cavities in the lungs. They can be treated with antibiotics. To eliminate the pus, patients may require drainage or surgery.
  • Breathing problems – When you breathe, you can have difficulties receiving enough oxygen. It’s possible that you’ll need to utilize a ventilator.
  • Acute respiratory distress syndrome (ARDS) is a condition in which the body’s This is the most serious type of respiratory failure. It’s a medical situation that requires immediate attention.
  • Pleural effusion – It is a type of pleural effusion that occurs when If you don’t treat your pneumonia, you could develop pleural effusion, which is fluid around your lungs in your pleura. Pleurae are thin membranes that line the inside of your rib cage and the outside of your lungs. If the fluid becomes infectious, it must be evacuated.
  • Damage to the kidneys, heart, and liver – These organs can be injured if they don’t get enough oxygen or if the immune system reacts too strongly to the infection.

Is pneumonia curable?

Antibiotics should not be stopped too soon if you have a bacterial infection; otherwise, the infection may not resolve completely. This indicates that your pneumonia may recur. Antibiotic resistance can be exacerbated by abruptly stopping antibiotics. Infections that are resistant to antibiotics are more difficult to treat. With at-home treatment, viral pneumonia usually clears up in 1 to 3 weeks. Antivirals may be required in some circumstances. Fungal pneumonia is treated with antifungal medicines. It may require a longer treatment time.

Pneumonia in pregnancy

Maternal pneumonia is pneumonia that develops during pregnancy. Pregnant women are more susceptible to infections like pneumonia. This is related to the immune system’s natural dampening that occurs during pregnancy.

Pneumonia symptoms do not alter by trimester. However, due to other discomforts you may be experiencing, you may notice some of them later in your pregnancy. If you’re expecting a child, call your doctor as soon as you see symptoms of pneumonia. Premature birth and low birth weight are two issues that can arise from maternal pneumonia.


Pneumonia is a bacterial, viral, or fungal lung infection. As a result of the immune system’s response to the infection, the air sacs in the lungs swell with pus and fluids. Symptoms include difficulty breathing, a cough with or without mucus, a fever, and chills. Your doctor will do a physical examination and examine your medical history in order to diagnose pneumonia. They may suggest more tests, such as a chest X-ray.

Treatment is determined by the infection’s cause. Antibiotics, antiviral drugs, and antifungal drugs may all be used. Pneumonia usually goes away in a few weeks. If your symptoms worsen, see a doctor very away, as you may need to be admitted to the hospital to avoid or treat more serious consequences.


How can I prevent my baby from pneumonia?

Vaccinations are the safest preventive measures against pneumonia and other fatal infections in infants.

Does pneumonia result in death?

Untreated pneumonia can be fatal for babies under 2 months of age and also for adults with underlying health conditions.

How long does it take to recover from pneumonia?

Pneumonia can be considered as a mild illness in people who are healthy and can, therefore, be cleared in 2 to 3 weeks of time. In those with other health issues and in older adults, it can take upto 2 months or more.

What are the early signs of pneumonia?

A cough and fever is an early sign of pneumonia. Usually, the cough is associated with phlegm or sputum that comes from the lungs during the infection. Apollo Hospitals has the Best Pulmonologist in India. To find the best doctors in your nearby city, visit the links below:

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