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Pneumonia is an infection of the lungs. It is a serious illness that can affect people of any age, but it is most common and most dangerous if existent in young children, people older than 65, and to those who have underlying medical problems such as heart disease, diabetes, and chronic lung disease. There is seasonal influence with a number of cases rising in the winter.

Community-acquired pneumonia (CAP), refers to pneumonia that develops in people who reside in a community.


During normal breathing, air inhaled through the nose and mouth travels from the trachea and bronchi and to the bronchioles. At the edge of the bronchioles, small air sacs called alveoli are present. Alveoli are air sacs of your lungs that are surrounded by tiny blood vessels called capillaries. The air sacs have thin walls that allow the exchange of gases. The blood flowing through the capillaries around the air sacs picks up oxygen that is breathed in and gives off carbon dioxide that is then breathed out. But if you have pneumonia, your alveoli swell and get filled with inflammatory cells and fluid, containing white blood cells, red blood cells, macrophages, fibrin, cell debris, and microorganisms. This phenomenon evokes a cough and makes it hard to breathe.

Due to air inhalation, the mouth and respiratory tract are constantly exposed to microorganisms. However, the body’s defences usually prevent microorganisms from entering and infecting the lungs. These defences include the immune system, the specialized shape of the nose and pharynx (which helps in trapping microorganisms and particulate matter from the air, thereby preventing them from entering the lungs), the ability to cough, and fine hair-like structures called cilia located on the bronchi. The cilia help in removing particles or bacteria that enter the bronchi by initiating a beating motion that pushes the particles up to the trachea, where it is coughed out. You can develop pneumonia if your defences are inadequate and you are exposed to a particularly strong microorganism, or to a very large number of microorganisms. As the microorganisms multiply, your immune system responds by sending white blood cells to the alveoli. The infected alveoli become inflamed (filled with white blood cells, proteins, fluid, and red blood cells). These changes lead to the symptoms of pneumonia.


Some groups of adults are at a greater risk of developing pneumonia. These include people who:

  • Are older than 65 years
  • Smoke cigarettes
  • Suffer from malnourishment due to health conditions or lack of food
  • Have underlying lung disease, including cystic fibrosis, asthma, or chronic obstructive pulmonary disease (emphysema)
  • Suffer from other medical problems including diabetes or heart disease
  • Have a weak immune system due to HIV, organ transplant, chemotherapy, or chronic steroid use
  • Face difficulty in coughing due to stroke, sedating drugs or alcohol, or limited mobility
  • Have suffered from a recent bout of viral upper respiratory tract infection including influenza


Pneumonia can be caused by a variety of microorganisms, such as viruses, bacteria, and, sometimes, fungi. The most common bacterial cause of pneumonia is Streptococcus pneumoniae (also called pneumococcus). Other bacterias responsible include Haemophilus influenzae, Legionella pneumophila, and Staphylococcus aureus. Other bacteria, such as mycoplasma, is a common cause of mild pneumonia but can occasionally cause serious disease. Viruses are estimated to be the cause of adult CAP in at least 20 % of cases. Influenza is a common viral cause of pneumonia. More recently, rhinoviruses which are the cause of the common cold have also been found to cause pneumonia. Other viruses that cause pneumonia in adults are human metapneumovirus, respiratory syncytial virus, parainfluenza virus, coronavirus, and adenovirus. Fungi rarely cause pneumonia in people who are generally healthy; people with a weakened immune system (those with HIV, organ transplant patients, or those on chemotherapy) are at higher risk of fungal infection. Let your doctor know if you have travelled recently or if you been to or lived in an area where a certain type of pneumonia is more common (e.g., Valley fever or coccidioidomycosis in the southwestern United States; the Middle East respiratory syndrome in the Arabian peninsula; the H7N9 strain of avian influenza in Asia). The risk of pneumonia caused by new microbes (so-called “emerging pathogens”) changes over time, but your doctor will know if any of the places that you have been to or lived in has put you at increased risk for pneumonia.


Common symptoms of pneumonia include fever, chills, shortness of breath, pain with breathing (pleurisy), a rapid heart and breathing rate, nausea, vomiting, diarrhoea, and a cough that often produces green or yellow sputum; occasionally the sputum is rust coloured. Most people have a fever (temperature greater than 100.5ºF or 38ºC), although older adults have fever less often. Shaking chills (called rigours) and a change in mental status (confusion, unclear thinking) can also occur.


Pneumonia is usually diagnosed through a medical history and physical examination as well as a chest x-ray. Depending on the severity of the illness and the person’s risk of complications further tests are performed.

  • Chest x-ray — A chest x-ray or computed tomography (CT) scan, is used to diagnose pneumonia when the history and physical examination support the diagnosis.
  • Sputum testing — A sample of sputum from a deep cough is collected for sputum testing. The culture of sputum is used to identify the microorganism that caused pneumonia and can help determine which antibiotic is best.
  • Urine antigen testing — Urine tests can be helpful to diagnose pneumonia caused by two bacteria, Streptococcus pneumoniae and Legionella pneumophila. These tests are easy to perform and provide quick results.
  • Blood testing – Patients with advanced pneumonia require blood testing. A CBC measures the number of different types of blood cells, including white blood cells (WBC) in a blood sample. A rise in the number of WBCs is an indication of a bacterial infection, including pneumonia. A blood culture is used to determine whether the infection has spread from the lungs into the bloodstream. A sample of blood from a vein is extracted and tested for bacteria. In ideal cases, bacteria should not be present in the bloodstream. Blood cultures help in identifying a pneumonia-causing bacteria and to guide the choice of antibiotic. A patient may be subjected to different antibiotics when results of the blood or sputum cultures are completed (usually after 48 to 72 hours).
  • Blood oxygen measurement — Pneumonia is known to decrease the amount of oxygen in the blood. Therefore, blood oxygen levels of pneumonia patients are constantly measured through a non-invasive device. In patients with advanced pneumonia, the oxygen level may be measured by withdrawing a sample of blood from an artery.
  • Bronchoscopy — Patients who suffer from severe pneumonia or who fail to improve or worsen during their hospitalization despite treatment with antibiotics may require further testing with bronchoscopy. In bronchoscopy, a thin and flexible tube with an attached camera is used to view the trachea and bronchi. This allows them to investigate the lungs directly as well as collect fluid samples or a biopsy. (Refer “Patient education: Flexible bronchoscopy (Beyond the Basics)”).


Initial treatment of CAP with antibiotics is based upon the organism that is likely to be causing pneumonia (called empiric treatment). Most patients recover with empiric treatment. People who are seriously ill or are at increased risk of complications may be hospitalized. Hospital monitoring usually includes measurement of heart rate, breathing rate, temperature, and oxygen levels. They are also given intravenous (IV) antibiotics. When they start recovering, they can be switched to antibiotic pills. Some patients need an extra oxygen supply to facilitate easy breathing. Patients who are still having a hard time breathing may need a breathing tube connected to a machine called a “ventilator.” Some patients who need to stay in the hospital are also given steroids to help reduce inflammation in the lungs. This medicine is not the same as the steroids athletes take to build up muscle. The duration of hospital stay is dependant on a person’s response to the treatment and if there is a history of medical problems. Some patients, including people with previous lung damage or disease, a weakened immune system, or infection in more than one lobe of the lungs (called multilobar pneumonia), may be slow to recover and require a longer hospitalization.
Antibiotic choice — Multiple antibiotic treatment regimens exist for treatment of CAP. Several factors, including the person’s underlying medical problems and the likelihood of being infected with a bacterium that is resistant to specific drugs, dictates the type of antibiotic used for treatment. It is paramount to complete the entire course of antibiotic regimen as per doctor’s instructions.


A person with pneumonia usually begins to recover after three to five days of antibiotic treatment. Fatigue and a persistent but a mild cough can last for one month or longer, although most people are able to resume their usual activities within a week. Patients treated in the hospital may not be able to resume their normal activities for three weeks or longer. All patients, should follow all the precautions and care suggested during the recovery period. It’s advised to consume plenty of fluids to avoid dehydration. Patients should complete the entire course antibiotic medication, even if one starts feeling better after a few days. All patients who are treated at home should have a follow-up visit or communication with a healthcare provider within several days of being diagnosed. This helps the doctor to monitor the recovery and to keep a check on complications if any. Patients who have been discharged from the hospital with a pneumonia diagnosis should have a follow-up visit, usually within one week. In addition, a later visit is often recommended to confirm that pneumonia has resolved, both in patients who were treated at home and those who were treated in the hospital. If your symptoms do not improve or get worse after you’ve started treatment, let your healthcare provider know.


A few complications of pneumonia can develop in some patients of high-risk groups. These complications can be related to pneumonia or to the drugs used to treat pneumonia. In addition, pneumonia may result in worsening of chronic conditions such as chronic obstructive pulmonary disease (emphysema) or congestive heart failure. Complications due to pneumonia include:

  • Fluid accumulation – Fluid gets collected between the covering of the lungs (pleura) and the inner lining of the chest wall; this is called a pleural effusion. If this fluid gets infected due to pneumonia (called empyema), a chest tube (or, less commonly, surgery) may be needed to drain the fluid.
  • Abscess – A collection of pus in the pneumonia-infected area known as an abscess. An abscess is usually treated with antibiotics; exceptionally, surgical removal is required.
  • Bacteremia – Bacteremia is a complication in which infection of pneumonia spreads from the lungs to the bloodstream. This is a serious complication since infection can spread quickly from the bloodstream to other organs. Bacteremia can plunge the blood pressure to a dangerously low point.
  • Death – Pneumonia can turn fatal in few cases. The 30-day mortality rate is approximately 5 to 10 % among patients admitted to a general medical ward but is as high as 30 % in patients with severe infection requiring admission to an intensive care unit.
  • Cardiovascular events – Some studies have shown that patients who have had pneumonia are at increased risk of having a cardiovascular event, such as a heart attack during recovery from pneumonia, and the risk persists for several years after the episode of pneumonia.

Complications due to medications used to treat pneumonia include: Diarrhoea and rash – Each medication have a list of side effects, and patients should be familiar with the side effects of the medications used to treat their pneumonia.


A person suspecting of pneumonia should seek medical care as early as possible. Pneumonia can be life-threatening if not treated, especially for people who are older than 65 years, alcoholic, have underlying medical problems, or have a weakened immune system. People who exhibit the following symptoms should visit a doctor promptly:

  • Fever and cough with phlegm that does not improve or worsens
  • New shortness of breath with normal daily activities
  • Chest pain with breathing
  • Feeling worse after a cold or the flu
  • Respiratory symptoms (as listed above) with new confusion


The pneumococcal vaccine is the best way to prevent pneumonia. Influenza (or “flu”) vaccine not only for prevents influenza but also prevents its complications, which includes pneumonia.
Another important way to prevent pneumonia is to quit smoking. Control of underlying conditions such as asthma, congestive heart failure, and diabetes can help to prevent pneumonia.
Infection control — Appropriate control measures help in preventing the spread of any type of infection, including pneumonia. Infection control is most commonly practised in healthcare settings but is useful in the community as well. Since pneumonia is spread by contact with infected respiratory secretions, people with pneumonia should avoid face-to-face contact with other people. Healthy habits like covering the mouth and nose while coughing or sneezing and disposing of the used tissues should be followed in the community.