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What is pneumonia?

Pneumonia is a type of lung infection that can affect one or both of the air sacs in the lungs, causing inflammation and leading to symptoms such as coughing, difficulty breathing, fever, and chest pain. It is usually caused by bacteria, viruses, or fungi, and it can range from mild to severe.

Pneumonia can be contagious, but the contagiousness depends on the underlying cause of the infection: bacterial or viral pneumonia. It's important to practice good hygiene to help prevent the spread of contagious infections, including those that can lead to pneumonia. If you suspect you have pneumonia or are experiencing symptoms, schedule an appointment with a St. Joseph Health primary care provider and follow their guidance to prevent spreading the infection to others.

Pneumonia causes

Pneumonia can be caused by a variety of infectious agents and environmental factors. Common causes include:

  • Bacteria: Bacterial pneumonia is often caused by Streptococcus pneumoniae, but other bacteria such as Haemophilus influenzae, Staphylococcus aureus, and Legionella pneumophila can also lead to pneumonia.

  • Viruses: Viral pneumonia is typically caused by influenza viruses, respiratory syncytial virus (RSV), and adenoviruses. COVID-19, caused by the SARS-CoV-2 virus, can also lead to pneumonia.

  • Fungi: Fungal pneumonia can result from exposure to certain types of fungi, such as Histoplasma, Cryptococcus, and Pneumocystis jirovecii (common in people with weakened immune systems).

  • Aspiration: Inhaling food, liquids, or foreign objects into the lungs can lead to aspiration pneumonia.

  • Community-Acquired Pneumonia (CAP): CAP refers to pneumonia acquired outside of healthcare settings and is often caused by bacteria like Streptococcus pneumoniae and Mycoplasma pneumoniae.

  • Hospital-Acquired Pneumonia (HAP): HAP can occur during hospital stays and is often caused by bacteria like Klebsiella pneumoniae or Pseudomonas aeruginosa.

  • Ventilator-Associated Pneumonia (VAP): VAP occurs in patients on ventilators and is typically caused by bacteria that are resistant to antibiotics.

  • Viral respiratory infections: Infections like the flu (influenza) and respiratory syncytial virus (RSV) can lead to viral pneumonia.

  • Immune system weakness: People with weakened immune systems, such as those with HIV/AIDS or undergoing chemotherapy, are more susceptible to various infections that can cause pneumonia.

  • Inhaling irritants: Inhaling irritants like chemicals, dust, or toxic fumes over time can contribute to a type of pneumonia called chemical or toxic pneumonia.

  • Lung diseases: Chronic lung diseases such as chronic obstructive pulmonary disease (COPD) and bronchiectasis can increase the risk of developing pneumonia.

  • Age and health factors: Infants, young children, the elderly, and individuals with underlying health conditions or compromised immune systems are more vulnerable to pneumonia.


Preventing pneumonia involves practicing good hygiene, getting vaccinated, avoiding exposure to irritants, and maintaining a healthy lifestyle. If you think you have pneumonia or are at risk, schedule an appointment with a St. Joseph Health primary care provider for proper diagnosis and treatment.

Pneumonia symptoms


Pneumonia diagnosis

  • Medical history and physical examination:

    • Your healthcare provider will ask about your symptoms, medical history, recent illnesses, and any risk factors.

    • They will perform a physical examination, including listening to your lungs with a stethoscope to check for abnormal sounds and breathing patterns.

  • A chest X-ray can reveal the presence of inflammation, fluid, or infection in the lungs. It's a common diagnostic tool for pneumonia.

  • Blood tests, such as a complete blood count (CBC) and a blood culture, can help identify the type of infection and the causative agent.

  • If you are producing mucus (sputum), a sample may be collected and analyzed to identify the specific microorganism causing the infection.

  • A pulse oximeter measures the oxygen saturation level in your blood. Low levels may indicate reduced lung function associated with pneumonia.

  • In some cases, a thin, flexible tube (bronchoscope) may be inserted through the nose or mouth to examine the airways and collect samples for analysis.

  • CT scan or MRI may be used if the diagnosis is unclear from a chest X-ray or if complications are suspected.

  • If a viral infection is suspected, tests such as polymerase chain reaction (PCR) may be used to detect viral genetic material in respiratory samples.


Pneumonia treatment options

Treating pneumonia typically involves a combination of medical interventions and self-care measures to alleviate symptoms, support recovery, and prevent complications. 

Here's an overview of how pneumonia is treated:

  • Medical treatment:

    • Antibiotics or antiviral medications

    • Pain and fever relievers

  • Rest and hydration

  • Monitor and seek medical attention


Pneumonia prevention tips

Preventing pneumonia involves a combination of healthy lifestyle practices and vaccinations to reduce the risk of infection. Here are some effective strategies:

  • Vaccination: Getting vaccinated can significantly lower the risk of certain types of pneumonia. The pneumococcal vaccine and the influenza (flu) vaccine are particularly important. These vaccines help protect against common bacterial and viral causes of pneumonia.

  • Practice good hygiene: Wash your hands frequently with soap and water, especially after being in public places or around sick individuals. Use hand sanitizer when soap and water are not available.

  • Avoid smoking: Smoking damages the lungs and weakens the body's ability to fight infections. Quitting smoking or avoiding exposure to secondhand smoke can reduce pneumonia risk.

  • Maintain respiratory health: Regular exercise, deep breathing exercises, and maintaining overall fitness can help keep your respiratory system strong and less susceptible to infections.

  • Proper rest: Ensure you're getting adequate sleep, as sleep is essential for maintaining a strong immune system.

  • Vitamin D: Some studies suggest that maintaining adequate vitamin D levels may help support immune function and reduce the risk of respiratory infections.

  • Environmental precautions: Be cautious in environments with air pollutants, chemicals, or allergens that could irritate the lungs.


Risk factors associated with pneumonia

  • Age: The very young (infants) and the elderly are at higher risk due to developing immune systems (in infants) or weakened immune systems (in the elderly).

  • Weakened immune system: Conditions such as HIV/AIDS, cancer, organ transplants, and autoimmune diseases can weaken the body's ability to fight off infections.

  • Chronic lung conditions: Conditions like chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis, and interstitial lung diseases can impair lung function and increase susceptibility to pneumonia.

  • Smoking: Smoking damages the lungs' natural defenses and weakens the immune system, making smokers more vulnerable to respiratory infections.

  • Underlying medical conditions: Chronic illnesses like diabetes, heart disease, and kidney disease can increase the risk of pneumonia.

  • Recent respiratory infections: Having had a recent cold, flu, or other respiratory infection can make the lungs more susceptible to bacterial invasion.

  • Environmental exposures: Regular exposure to pollutants, dust, chemicals, or fumes can irritate the lungs and increase vulnerability to pneumonia.

  • Age care facilities: Residents of long-term care facilities or nursing homes have a higher risk due to close living quarters and potential exposure to infections.


Facts about walking pneumonia

Walking pneumonia, also known as atypical pneumonia or mycoplasma pneumonia, is a milder form of pneumonia compared to the more severe and traditional bacterial or viral pneumonias. It is called "walking pneumonia" because many people who have it can continue with their daily activities and may not appear as sick as those with typical pneumonia who are bedridden.

Walking pneumonia is primarily caused by a bacterium called Mycoplasma pneumoniae. It tends to affect older children, teenagers, and young adults more often than other age groups. The symptoms of walking pneumonia can be similar to those of a common cold or flu, making it sometimes difficult to distinguish. Common symptoms may include:

  • Persistent cough

  • Low-grade fever

  • Sore throat

  • Fatigue

  • Headache

  • Muscle aches

  • Chills

While walking pneumonia is generally less severe than other forms of pneumonia, it's important to seek medical attention with a St. Joseph Health primary care provider if you experience these symptoms, especially if they worsen or if you have difficulty breathing.

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