Pneumonia Symptoms Causes and Risk Factors

Pneumonia facts

  • Pneumoniais inflammation of the airspaces in the lungs, most commonly due to an infection.
  • Pneumonia may be caused by viruses, bacteria, or fungi.
  • The most common bacterial type that causes pneumonia is Streptococcuspneumoniae.

Signs and symptoms of pneumonia include:

  • Fever
  • Chills
  • Cough
  • Shortness of breath
  • Fatigue
  • Community-acquired pneumonia (CAP) is acquired outside of the health-care setting and is typically less severe than hospital-acquired pneumonia (HAP).
  • About 20% of those with CAP require treatment in a hospital.
  • Antibiotics treat pneumonia by controlling the bacterial or fungal infection. The initialchoice of antibioticdepends on the organism presumed to be causing the infection as well as local patterns of antibiotic resistance.
  • Pneumonia can be fatal in up to 30% of severe cases that are managed in the intensive-care setting.
  • Complications of pneumonia include sepsis, pleural effusion, and empyema.
  • Influenzaand respiratory syncytial virus(RSV) are the most common viral causes of pneumonia.
  • A chest X-rayis typically done to diagnose pneumonia.

Risk factors for pneumonia include age over 65 or under 2, having certain chronic medical conditions (including underlying lung disease, cigarettesmoking, alcoholism, and neurological problems), or sustaining injuries that interfere with swallowing orcoughing.


  • Pneumonia is an inflammation of the airspaces in the lung most commonly caused by infections. Bacteria, viruses, or fungi can cause the infection. There are also a few noninfectious types of pneumonia that are caused by inhaling or aspirating foreign matter or toxic substances into the lungs.
  • Common in elderly people and often occurs when the immune systembecomes weakened via a prior infection or another condition.
  • Pneumonia is generally more serious when it affects older adults, infants and young children, those with chronic medical conditions, or those with weakened immune function. 

Types of Pneumonia:

Pneumonia can be classified in different ways. Doctors often refer to pneumonia based upon the way that the infection is acquired, such as community-acquired pneumonia or hospital-acquired pneumonia.

  • Community-acquired pneumonia (CAP), as the name implies, develops outside of the hospital or health-care environment. It is more common than hospital-acquired pneumonia.
  • Hospital-acquired pneumonia (HAP) is acquired when an individual is already hospitalized for another condition. HAP is generally more serious because it develops in ill patients already hospitalized. Being on a ventilator for respiratory support increases the risk of acquiring HAP.
  • Other classification systems for pneumonia describe the way the inflammatory

cells infiltrate the lung tissue or the appearance of the affected tissue (see the following examples).

  • Bronchopneumonia causes scattered, patchy infiltrates of inflammation in the air sacs throughout the lungs. It is more diffuse than lobar pneumonia.
  • Lobar pneumonia causes an inflammation of one lobe of a lung and typically involves all the airspaces in a single lobe.
  • Lipoid pneumonia is characterized by the accumulation of fatswithin the airspaces. It can be caused by aspiration of oils or associated with airway
  • Sometimes, types of pneumonia are referred to by the type of organism that causes the inflammation, such as bacterial pneumonia, viral pneumonia, or fungal pneumonia. The specific organism name may also be used to describe the types of pneumonia, such as pneumococcal (Streptococcus pneumoniae) pneumonia or Legionella
  • Other types of pneumonia that are commonly referenced include the following:
  • Aspiration pneumonia develops as a result of inhaling food or drink, saliva, or vomit into the lungs. This occurs when the swallowing reflex is impaired, such as with brain injuryor in an intoxicated person.
  • Several types of bacteria, including Legionella pneumophilaMycoplasma pneumoniae, and Chlamydophilapneumoniae, cause atypical pneumonia. It is sometimes called “walkingpneumonia” and is referred to as atypical because its symptoms differ from those of other types of bacterial pneumonia.
  • Pneumonia that arises from being on a ventilator for respiratory support in the intensive-care setting is known as ventilator-associated pneumonia.

Causes of Pneumonia:

  • Streptococcus pneumoniae, a type of bacteria, is the most common cause of pneumonia.Legionella pneumophilais the bacterial type that causes the pneumonia known as Legionnaires’ disease. Other bacteria types that can cause pneumonia include the bacteria that cause so-called “atypical” pneumonia, Legionella pneumophilaMycoplasma pneumoniae, and Chlamydophila pneumonia.
  • The most common cause of viral pneumonia in adults is the influenza virus. A number of different respiratory viruses cause pneumonia in children, such as respiratory syncytial virus (RSV). While viral pneumonia tends to be less severe than bacterial pneumonia, there is a risk of developing secondary bacterial pneumonia when viral pneumonia is present. Other virus types that can cause pneumonia include emeaslesandvaricella (chickenpox) viruses. Rarely, certain viruses may develop lethal pneumonias such as SARS (severe acute respiratory syndrome) or MERS (Middle East respiratory syndrome); both diseases are caused by different coronaviruses.
  • Fungi that cause pneumonia includeCryptococcus,Histoplasma, and Coccidioides. In most cases, these organisms don’t cause illness, but they can cause pneumonia in some people. Fungal infections are most common in those with weakened immune systems due toHIV/AIDS or those taking medications that suppress immune function. Another infection that is considered a fungal type of pneumonia is Pneumocystis jiroveci, formerly known as Pneumocystis carinii. This organism became known as a frequent cause of pneumonia in patients with HIV/AIDS. 

Symptoms and Signs of pneumonia

Symptoms and signs of pneumonia may be mild or severe and depend upon someone’s overall state of health as well as the type of organism causing the pneumonia. Severe symptoms include

  • Cough
  • Chest Painwhen breathing or coughing
  • Labored breathing or shortness of breath
  • Coughing up phlegm
  • Fever
  • Chills
  • Nausea& vomiting
  • Diarrhea
  • Other possible symptoms that can accompany the respiratory symptoms.
  • Infants and newborns may not show specific symptoms of pneumonia.
  • Instead, they may appear restless or lethargic. They may have a fever or cough or vomit.
  • Older adults or those who have weak immune systems may also have fewer symptoms and a lower temperature.
  • A change in mental status, such as confusion, can develop in older adults with pneumonia.

Complications of Pneumonia:

  • There are a number of potential complications of pneumonia.
  • The infection that causes pneumonia can spread to the bloodstream, causing sepsis. Sepsis is a serious condition that can result in lowering of blood pressure and failure of oxygen to reach the tissues of the body..
  • Another complication is the accumulation of fluid in the space between the lung tissue and the chest wall lining, known as apleural effusion.
  • The organisms responsible for the pneumonia may infect the fluid in a pleural effusion, known as an empyema.
  • Pneumonia can also result in the formation of anabscess(collection of pus) within the lungs or airways.

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