Introduction

A respiratory infection that affects the lungs is called pneumonia. It can range in severity from mild to severe and is caused by bacteria, viruses, or fungi. Pneumonia is a common illness that affects millions of people every year, and it can be especially dangerous for young children, the elderly, and people with weakened immune systems. Let us discuss and learn more about the different types of pneumonia, their symptoms, and their characteristics.¹

Overview of the different types of pneumonia

There are several types of pneumonia that can cause respiratory distress and discomfort. Let us see more about in detail:

Bacterial Pneumonia

Definition:

Bacterial pneumonia is a type of lung infection that is caused by bacteria. There are a few types of bacterial pneumonia, they include:

• Community-acquired pneumonia (CAP)
• Hospital-acquired pneumonia (HAP) 
• Ventilator-associated pneumonia (VAP) 
• Healthcare-associated pneumonia (HCAP) ^1,4

Causes

Bacterial pneumonia is caused by different types of bacteria like: 

• Streptococcus pneumonia, Group A Streptococcus 
• Klebsiella pneumonia
• Haemophilus influenza
• Moraxella catarrhalis
• Anaerobes 
• Gram-negative organisms.
• Methicillin-resistant Staphylococcus aureus (MRSA)
• Escherichia coli
• Other Enterobacteriaceae.^1,2

Symptoms

• High fever (up to 105°F) and profuse sweating.
• Rapidly increased breathing and a high pulse rate.
• Bluish lips and nailbeds (cyanosis) indicate a lack of oxygen in the blood.
• Confusion due to changes in mental state.³

Diagnosis

Diagnosis of bacterial pneumonia involves clinical evaluation, laboratory evaluation, and radiological evaluation.

• Clinical evaluation: It involves taking a patient’s medical history and conducting a physical examination to identify signs and symptoms of bacterial pneumonia.
• Laboratory evaluation: This includes blood tests to check for inflammation and infection, sputum analysis, urine antigen testing, and polymerase chain reaction.
• Radiological evaluation: It involves a chest X-ray or CT scan to identify pulmonary infiltrates or effusion.
• Bronchoalveolar lavage: This is performed in intubated patients to collect samples for bacterial culture.⁴

Viral Pneumonia

Definition

Viral pneumonia is a condition where the alveoli (air sacs) in the lungs are inflamed due to a viral infection or immune response.⁵

Causes

Viral pneumonia is caused by different types of viruses like: 

• Respiratory syncytial virus (RSV) 
• Influenza A, B, and C viruses – the greatest cause of mortality and morbidity among viral types, with multiple subtypes including avian and swine flu
• Human metapneumovirus 
• Parainfluenza viruses type 1, 2, 3, and 4 
• Human bocavirus Coronavirus 
• Adenovirus 
• Varicella-zoster virus 
• Hantavirus
• Epstein-Barr virus 
• Herpes simplex virus 
• Cytomegalovirus (CMV) 
• Measles 
• Coronavirus
• Metapneumovirus⁵

Symptoms

Symptoms of viral pneumonia develop gradually over several days:

• Early symptoms are similar to the flu, including fever, dry cough, headache, muscle pain, and weakness.
• As the illness progresses, symptoms typically worsen and may include increasing cough, shortness of breath, and muscle pain.
• In severe cases, there may be a high fever and blueness of the lips.

Symptoms of viral pneumonia in newborns and infants:

• May not show any signs of infection or asymptomatic.
• Vomiting
• Fever and cough
• Restlessness, lethargy, and lack of energy

Symptoms of viral pneumonia in older adults and people with serious illnesses or weak immune systems:

• Fewer and milder symptoms compared to younger individuals.
• Sometimes lower than normal body temperature
• Sudden changes in mental awareness in older adults
• Symptoms of any underlying chronic lung disease may worsen.³

Diagnosis

Diagnosing viral pneumonia is important because there are specific treatments available. While history and physical examination may not provide a definitive diagnosis, laboratory tests can help identify the virus causing the pneumonia. Some common diagnostic tests for viral pneumonia are:

• CBC with a differential blood test can show whether the white blood cell count is elevated, normal, or decreased.
• ELISA rapid antigen tests can identify viral pneumonia pathogens in real time.
• PCR testing can identify viruses, including CMV, RSV, HPV, and coronaviruses.
• Chest X-ray and CT scan imaging tests can show the presence of pneumonia in the lungs.⁵

Mycoplasma Pneumonia

Definition

Mycoplasma pneumonia is a type of bacteria that can infect people and cause respiratory infections, including pneumonia. While it typically affects the upper respiratory system, it can also lead to more serious lung infections.⁶

Causes

• Mycoplasma pneumonia is caused by the bacteria called Mycoplasma pneumonia. 
• This bacterium is transmitted through respiratory secretions, such as droplets from coughing or sneezing. It can also be spread through direct contact with contaminated objects, such as tissues or towels. 
• The bacterium is highly contagious and can easily spread through households, schools, and other close-contact settings.⁷

Symptoms

Symptoms commonly associated with Mycoplasma pneumonia include:

• Mycoplasma pneumonia can cause fever and chills in infected individuals.
• Cough 
• Feeling tired or fatigued
• Shortness of breath 

Symptoms usually appear within 1 to 4 weeks after the bacteria has infected the body.⁸

Diagnosis

• History: Diagnosis is often based on the patient’s symptoms and history of exposure to the bacteria.
• PCR tests: Mycoplasma pneumoniae is difficult to culture, but PCR tests can provide a rapid and accurate diagnosis.
• Serologic tests look for changes in antibody levels and can also help diagnose infection.
• Chest X-rays may show a pattern of small nodules or pattern or patchy areas of consolidation in the lungs.⁶

Fungal Pneumonia

Definition

Fungal pneumonia is a type of lung infection caused by certain types of fungi. It usually affects people who have weakened immune systems or chronic health problems, or who have been exposed to fungi from contaminated soil or bird droppings.⁹

Causes

• Pneumocystis jirovecii: Pneumocystis pneumonia is a serious type of fungal pneumonia caused by Pneumocystis jirovecii and typically affects individuals with weakened immune systems due to diseases like HIV/AIDS or the use of drugs that suppress the immune system.
• Other fungi that may cause fungal pneumonia include Coccidioidomycosis, Histoplasmosis, and Cryptococcus.⁹

Symptoms

Fungal pneumonia can cause symptoms that develop gradually over several days or weeks. They include:

• Fever
• Chest pain
• Cough
• Chills
• Breathing difficulty
• Tiredness or fatigue.¹⁰

Diagnosis

• Bronchoalveolar lavage: The diagnosis of fungal pneumonia typically involves taking a sample from a patient’s lungs. The sample is typically mucus, either from the patient’s coughing up sputum or from a process known as bronchoalveolar lavage.
• Biopsy: The diagnosis of fungal pneumonia is made using a small sample of lung tissue (a biopsy). The laboratory receives the patient’s sample, which is often going to be inspected under a microscope.
• Polymerase chain reaction (PCR): PCR can also be used to detect the DNA of specific fungal organisms in different types of samples.
• Blood Test: A blood test can detect certain components of the fungal cell wall, such as β-D-glucan, which can help diagnose fungal pneumonia. ¹⁰

Aspiration Pneumonia

Definition

When food or liquid is inhaled into the lungs or airways as opposed to being swallowed, it leads to aspiration pneumonia.¹¹

Causes

Here are the causes of aspiration pneumonia:

• Decreased alertness due to medications, illness, surgery, or other factors.
• Coma or altered consciousness.
• Consuming excessive amounts of alcohol.
• Using illicit drugs, particularly opioids, that reduce alertness.
• Advanced age.
• Impaired gag reflex in individuals who are unconscious or semi-conscious after a stroke or brain injury.
• Swallowing difficulties.
• Being hospitalized, increases the risk.
• Inhaled materials may include saliva, vomit, liquids, and foods.
• The specific bacteria causing pneumonia can vary based on factors such as overall health, living environment (home or long-term care facility), recent hospitalization, recent antibiotic use, and weakened immune system. ¹¹

Symptoms

• Pain in the chest
• Coughing up phlegm that may be greenish or dark in shade, and may contain pus or blood
• Feeling tired or fatigued
• Running a fever
• Shortness of breath
• Wheezing or noisy breathing
• Extreme sweating
• Difficulty swallowing
• Confusion or mental changes¹¹

Diagnosis

The following tests are used to diagnose aspiration pneumonia:

• Listening to chest sounds using a stethoscope to check for crackles or abnormal breath sounds
• Tapping on the chest wall to feel for abnormal sounds
• Chest X-ray 
• Arterial blood gas test
• Blood culture
• Bronchoscopy (in some cases)
• Complete blood count (CBC)
• CT scan of the chest
• Sputum culture
• Swallowing tests to evaluate swallowing ability¹¹

Prevention of Pneumonia

Vaccinations

• To avoid seasonal influenza, make sure to get a flu shot every year. 
• The flu can lead to pneumonia, so preventing the flu is a good way to prevent pneumonia.
• Pneumococcal pneumonia is a prevalent type of bacterial pneumonia that should be prevented in particular populations. These populations include children under the age of two, children 2-5 with specific health conditions, adults 19–64 with specific chronic health disorders or risk factors, and all adults 65 and older.
• Depending on their health, additional pneumococcal vaccinations may be advised for children and adults who are at higher risk for pneumococcal illness.
• Other vaccines, including pertussis (whooping cough), COVID-19, chickenpox, and measles, can also prevent infections that may lead to pneumonia.
• Speak to your doctor about whether you and your family are up to date on your vaccines and to determine if any of these vaccines are appropriate for you.¹²

Good hygiene

Having good hygiene is an important step in the prevention of pneumonia. 

• Wash your hands often to maintain good hygiene.

• Quit smoking to reduce your risk of pneumonia.
• Regular physical activity can help to keep your immune system strong.
• Eating healthy is also important to maintain a strong immune system and prevent pneumonia.¹³

Lifestyle changes

Here are some lifestyle changes you can make to prevent pneumonia:

• Be aware of any symptoms that linger for more than a few days after respiratory infections.
• Practice good health habits such as eating a healthy diet, getting enough rest and regular exercise to prevent respiratory illnesses.
• Manage existing health conditions like asthma, COPD, diabetes, and heart disease properly.
• Wash your hands frequently with soap and water or use alcohol-based hand disinfectants to kill germs.
• Quit smoking as it damages your lungs and increases your risk of pneumonia.
• If you have difficulty swallowing, eat smaller meals of thickened food and sleep with the head of your bed raised.
• If you have a planned surgery, follow your healthcare provider’s recommendations to prevent food or drink from getting into your airway while you are sedated.
• If your immune system is impaired, your healthcare provider may recommend antibiotics to prevent bacteria from growing in your lungs.^12,13

Treatment for different types of pneumonia

• Treatment for pneumonia depends on the severity and risk factors.
• Mild pneumonia can be treated with medicines prescribed by a healthcare provider 
• Antibiotics may be prescribed for bacterial pneumonia, while antiviral and antifungal medicines are prescribed for viral and fungal pneumonia, respectively.
• It’s important to take antibiotics as prescribed to avoid the risk of pneumonia coming back.
• If the pneumonia is serious, hospital treatment may be required to get proper antibiotics and fluids through an IV line, oxygen therapy, or being put on a ventilator in severe cases.
• Procedures or surgeries may be needed to remove seriously infected or damaged parts of the lung to prevent pneumonia from coming back.¹⁴

Conclusion

In conclusion, understanding the different types of pneumonia is crucial for proper diagnosis and treatment. Identifying the specific type of pneumonia and its underlying cause is essential for selecting the appropriate treatment plan. Although some types of pneumonia can be prevented with vaccines and good hygiene practices, anyone can still contract pneumonia, and it is vital to seek medical attention if you experience symptoms.

Disclaimer: The information included on this site is for educational purposes only and is not intended to be a substitute for medical treatment by a healthcare professional. Because of unique individual needs, the reader should consult their physician to determine the appropriateness of the information for the reader’s situation.

References

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2. Pahal P, Rajasurya V, Sharma S. Typical Bacterial Pneumonia. [Updated 2022 Aug 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534295/ 
3. Association AL. Pneumonia symptoms and diagnosis [Internet]. [cited 2023 May 12]. Available from: https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia/symptoms-and-diagnosis 
4. Sattar SBA, Sharma S. Bacterial Pneumonia. [Updated 2022 Aug 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513321/ 
5. Freeman AM, Leigh, Jr TR. Viral Pneumonia. [Updated 2022 Jul 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513286/ 
6. Abdulhadi B, Kiel J. Mycoplasma Pneumonia. [Updated 2023 Jan 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430780/ 
7. Mycoplasma pneumoniae causes and how it spreads [Internet]. Centers for Disease Control and Prevention; 2022 [cited 2023 May 12]. Available from: https://www.cdc.gov/pneumonia/atypical/mycoplasma/about/causes-transmission.html 
8. Mycoplasma pneumoniae signs and symptoms [Internet]. Centers for Disease Control and Prevention; 2022 [cited 2023 May 12]. Available from: https://www.cdc.gov/pneumonia/atypical/mycoplasma/about/signs-symptoms.html 
9. Association AL. What causes pneumonia? [Internet]. [cited 2023 May 12]. Available from: https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia/what-causes-pneumonia 
10. Pneumocystis pneumonia [Internet]. Centers for Disease Control and Prevention; 2021 [cited 2023 May 12]. Available from: https://www.cdc.gov/fungal/diseases/pneumocystis-pneumonia/index.html#:~:text=Pneumocystis%20pneumonia%20(PCP)%20is%20a,to%20fight%20germs%20and%20sickness. 
11. What is Aspiration Pneumonia? [Internet]. [cited 2023 May 12]. Available from: https://www.pennmedicine.org/for-patients-and-visitors/patient-information/conditions-treated-a-to-z/aspiration-pneumonia#:~: 
12. Association AL. Preventing pneumonia [Internet]. [cited 2023 May 12]. Available from: https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia/preventing-pneumonia 
13. Prevention [Internet]. U.S. Department of Health and Human Services; [cited 2023 May 12]. Available from: https://www.nhlbi.nih.gov/health/pneumonia/prevention#:~: 
14. Treatment [Internet]. U.S. Department of Health and Human Services; [cited 2023 May 12]. Available from: https://www.nhlbi.nih.gov/health/pneumonia/treatment#:~