What are the symptoms of bacterial pneumonia? What causes bacterial pneumonia? How is bacterial pneumonia treated? Get the answers to these questions and more.

Symptoms of Bacterial Pneumonia

The severity of bacterial pneumonia symptoms can vary. Some people only experience mild symptoms, while others develop life-threatening complications. According to the American Lung Association, typical symptoms of bacterial pneumonia include:

• Chest pain
• Shortness of breath
• A cough that may produce yellow or green mucus
• Fever
• Tiredness
• Chills

Symptoms of bacterial pneumonia tend to be similar in both children and adults. According to the American Academy of Pediatrics, toddlers and infants may cry more than usual, have reduced energy, and appear pale.

Causes of Bacterial Pneumonia

Bacterial pneumonia is an inflammation of the lungs due to bacterial infection. Different types of bacteria can cause pneumonia, and this type of pneumonia can occur in both lungs, one lung, or one section of a lung. Pneumococcal disease, which Streptococcus pneumoniae causes, is a major cause of bacterial pneumonia. In the United States, it occurs in around 900,000 people each year, and approximately 400,000 of these require admission to a hospital.

Other types of bacteria can also cause pneumonia and significant harm, alongside other types of pathogen, including viruses, parasites, and fungi.

Complications of Bacterial Pneumonia

Bacterial pneumonia might be complicated in both children and adults. Anyone can develop complications from bacterial pneumonia, but people with weaker immune systems, younger children, and older adults have a higher risk. Complications may include:

• Respiratory failure: This might develop if oxygen levels in the lungs drop too low or if carbon dioxide levels spike. It can occur due to inadequate breathing ability, and respiratory failure may even cause lung function to stop completely.
• Sepsis: This occurs when an infection causes an overwhelming inflammatory response throughout the body. Sepsis can lead to failure in multiple organs and may be life-threatening.
• Lung abscess: This occurs when an infected pocket of pus forms in the lung.
• Empyema: This is an infectious collection of pus in the pleural cavity that surrounds the outside of lungs.

Swift treatment is vital for reducing the risk of complications.

Types of Bacterial Pneumonia

Pneumonia is often classified as either community-acquired pneumonia or hospital-acquired pneumonia. The classification refers to the location in which a person acquired the infection.

Community-acquired pneumonia is the by far more the common type. If a person develops community-acquired pneumonia, it means infection occurred outside of a hospital. The pneumococcal bacterium usually enters the lungs after a person breathes in particles or droplets from a sneeze or cough from another individual who has the infection. Amongst the most common causes of community-acquired pneumonia are bacteria, including Streptococcus pneumoniae, the most common bacteria, and Haemophilus influenzae.

Hospital-acquired pneumonia develops while in the hospital and occurs after at least 48 hours of being admitted. Most patients with hospital-acquired pneumonia are very ill, and they become colonized with a bacterium in their mouth and/or upper respiratory tract that then enters their lungs to cause infection. The most common causes of hospital-acquired pneumonia are Pseudomonas aeruginosa and Staphylococcus aureus.

Risk Factors for Bacterial Pneumonia

Although anyone can develop bacterial pneumonia, certain factors increase the risk. According to the Cleveland Clinic, people who have a weakened immune system as a result of cancer, cancer treatment, or an organ transplant face an increased risk of bacterial pneumonia.

Treatment for Bacterial Pneumonia

The treatment for bacterial pneumonia typically involves antibiotics. The specific antibiotic used will depend on the type of bacteria causing the infection. In some cases, hospitalization may be necessary, particularly if the person has a severe case of pneumonia or has other underlying health conditions that increase the risk of complications.

What are the steps to prevent bacterial pneumonia? Vaccination is one of the most effective ways to prevent bacterial pneumonia. The pneumococcal vaccine can help protect against the most common cause of bacterial pneumonia, Streptococcus pneumoniae. Additionally, practicing good hygiene, such as washing your hands regularly and covering your coughs and sneezes, can help reduce the spread of the bacteria that cause pneumonia.

When to Seek Medical Attention

A person who suspects symptoms of pneumonia should seek medical attention. The cause of a particular presentation of pneumonia can be difficult to determine without seeing a physician. Since the treatments for bacterial and viral pneumonia are different, finding the correct cause is vital for choosing the appropriate treatment regimen.

Bacterial pneumonia: Symptoms, causes, and treatment

Bacterial pneumonia is an inflammation of the lungs due to bacterial infection. Different types of bacteria can cause pneumonia. This type of pneumonia can occur in both lungs, one lung, or one section of a lung.

Pneumococcal disease, which Streptococcus pneumoniae causes, is a major cause of bacterial pneumonia. In the United States, it occurs in around 900,000 people each year, and approximately 400,000 of these require admission to a hospital.

Pneumococcal pneumonia is fatal in roughly 5­-7 percent of people who stay in hospital for treatment.

Other types of bacteria can cause pneumonia and significant harm, alongside other types of pathogen, including viruses, parasites, and fungi.

In this article, we look at the symptoms, causes, and treatments of bacterial pneumonia, as well as how to prevent the disease.

Share on PinterestPneumonia might cause chest pain or shortness of breath.

The severity of bacterial pneumonia symptoms can vary. Some people only experience mild symptoms while others develop life-threatening complications.

According to the American Lung Association, typical symptoms of bacterial pneumonia include:

• chest pain
• shortness of breath
• a cough that may produce yellow or green mucus
• fever
• tiredness
• chills

Symptoms of bacterial pneumonia tend to be similar in both children and adults. According to the American Academy of Pediatrics, toddlers and infants may cry more than usual, have reduced energy, and appear pale.

A person who suspects symptoms of pneumonia should seek medical attention. The cause of a particular presentation of pneumonia can be difficult to determine without seeing a physician.

Since the treatments for bacterial and viral pneumonia are different, finding the correct cause is vital for choosing the appropriate treatment regimen.

Complications

Bacterial pneumonia might be complicated in both children and adults. Anyone can develop complications from bacterial pneumonia, but people with weaker immune systems, younger children, and older adults have a higher risk.

Complications may include the following:

• Respiratory failure: This might develop if oxygen levels in the lungs drop too low or if carbon dioxide levels spike. It can occur due to inadequate breathing ability, and respiratory failure may even cause lung function to stop completely.
• Sepsis: This occurs when an infection causes an overwhelming inflammatory response throughout the body. Sepsis can lead to failure in multiple organs and may be life-threatening.
• Lung abscess: This occurs when an infected pocket of pus forms in the lung.
• Empyema: This is an infectious collection of pus in the pleural cavity that surrounds the outside of lungs

Swift treatment is vital for reducing the risk of complications.

Small air sacs called alveoli are within the lobes of each lung. Normally, these air sacs aid in the body’s gas exchange, while inhaling oxygen and exhaling carbon dioxide.

When a person develops pneumonia, the air sacs experience inflammation, which can cause them to fill with fluid. If the air sacs fill with fluid rather than air, breathing might become difficult.

In some cases, the lungs and the rest of the body may not get enough oxygen.

Types

Pneumonia is often classified as either community-acquired pneumonia or hospital-acquired pneumonia. The classification refers to the location in which a person acquired the infection.

Community-acquired pneumonia is the by far more the common type. Other, less common types can occur, such as healthcare-associated pneumonia (HCAP) and ventilator-associated pneumonia (VAP).

If a person develops community-acquired pneumonia, it means infection occurred outside of a hospital. The pneumococcal bacterium usually enters the lungs after a person breathes in particles or droplets from a sneeze or cough from another individual who has the infection.

Amongst the most common causes of community-acquired pneumonia are bacteria, including Streptococcus pneumoniae, the most common bacteria, and Haemophilus influenzae.

However, viruses, including influenza viruses, can also cause community-acquired pneumonia.

Hospital-acquired pneumonia develops while in the hospital and occurs after at least 48 hours of being admitted.

Most patients with hospital-acquired pneumonia are very ill, and they become colonized with a bacterium in their mouth and/or upper respiratory tract that then enters their lungs to cause infection.

The most common causes of hospital-acquired pneumonia are Pseudomonas aeruginosa and Staphylococcus aureus.

Risk factors

Although anyone can develop bacterial pneumonia, certain factors increase the risk.

According to the Cleveland Clinic, people who have a weakened immune system as a result of cancer, cancer treatment, or an organ transplant face an increased risk of bacterial pneumonia.

Smoking tobacco products and having a long-term lung condition, such as emphysema or chronic bronchitis COPD, increases the risk. Being over 65 years of age and having had recent surgery also puts people at a higher risk.

Share on PinterestA chest X-ray can help identify areas of inflammation.

Healthcare professionals can create a diagnosis of bacterial pneumonia after completing various diagnostic tests and performing a thorough history and physical exam. During a physical exam, the doctor will listen to the lungs to determine whether they sound dysfunctional.

In most cases, a doctor will conduct a chest X-ray to check for areas of inflammation and infiltrate in the lungs.

Additional tests may also support a pneumonia diagnosis, such as a chest CT scan and an arterial blood gas (ABG) sample. An ABG measures the amount of oxygen and carbon dioxide in the arterial blood, in addition to other things like pH and bicarbonate levels, and helps determine breathing efficiency and gas exchange.

The medical team might also perform a bronchoscopy to look into the lung airways and obtain a biopsy or a mucus sample. The operating doctor inserts a small tube with a tiny camera attached through the mouth into the lungs.

A person receives medication before a bronchoscopy to numb and relax the throat, and the doctor typically also gives intravenous sedating medication.

Share on PinterestA person can receive a vaccine for pneumonia from the age of 2 months.

One of the best ways to prevent bacterial pneumonia is by preserving the strength of the immune system. Eating healthy foods, getting enough rest, and frequent hand-washing are good starting points.

Since bacterial pneumonia can develop as a complication of the flu, getting an annual flu shot may prevent pneumonia.

Two different pneumococcal vaccines are also available for reducing a person’s risk of developing bacterial pneumonia due to S. pneumoniae bacterium, the most common cause of bacterial pneumonia. These vaccines are the PCV13 and PPSV23, which protect against 13 and 23 strains of the pneumococcal bacterium respectively.

Doctors recommend that adults over 65 years of age have both types of vaccine. Children should receive a series of PCV13 vaccination starting at 2 months of age. Overall health status and age may affect the recommendation for pneumococcal vaccination.

Ultimately, a doctor will be able to determine which vaccine you may need and when to have them.

Recognizing bacterial pneumonia

In addition to bacteria, viruses and fungi can also cause pneumonia. Regardless of the cause, symptoms of pneumonia are often similar.

The similar symptoms in people with both viral and bacterial pneumonia can make determining the cause difficult.

According to the Cleveland Clinic, symptoms of bacterial pneumonia tend to be more severe than viral pneumonia and can come on suddenly. Symptoms of viral pneumonia tend to develop more slowly and are more similar to the flu at first.

One way to tell the difference between viral and bacterial pneumonia is a mucus sample, also called a sputum sample. A person coughs up a mucus sample, or a doctor obtains one from the lungs during a bronchoscopy.

A medical professional then analyzes it in the laboratory to determine the presence of any bacteria.

Supportive treatment for pneumonia, such as supplemental oxygen and fever-reducing medicine, is often the same regardless of the cause. The main difference in treatment is that antibiotics are for treating bacterial pneumonia but are ineffective for viral pneumonia.

Q:

Is bacterial pneumonia more dangerous than viral pneumonia.

A:

Depending on immune system function, either type of pneumonia could be dangerous, especially in those with a weaker immune system.

For example, if a person is an older adult and has weaker immune system functioning, a viral infection, such as influenza, may develop into viral pneumonia, or it could lead to further weakening of the immune system, in which secondary bacterial pneumonia could occur.

A person in better overall health with a better functioning immune system has a lower risk of having pneumonia in general. However, is an individual has significant or worsening symptoms that could due to any type of pneumonia, visiting a physician is the best course of action for appropriate diagnosis and treatment.

Stacy Sampson, DOAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Was this helpful?

Bacterial pneumonia: Symptoms, causes, and treatment

Bacterial pneumonia is an inflammation of the lungs due to bacterial infection. Different types of bacteria can cause pneumonia. This type of pneumonia can occur in both lungs, one lung, or one section of a lung.

Pneumococcal disease, which Streptococcus pneumoniae causes, is a major cause of bacterial pneumonia. In the United States, it occurs in around 900,000 people each year, and approximately 400,000 of these require admission to a hospital.

Pneumococcal pneumonia is fatal in roughly 5­-7 percent of people who stay in hospital for treatment.

Other types of bacteria can cause pneumonia and significant harm, alongside other types of pathogen, including viruses, parasites, and fungi.

In this article, we look at the symptoms, causes, and treatments of bacterial pneumonia, as well as how to prevent the disease.

Share on PinterestPneumonia might cause chest pain or shortness of breath.

The severity of bacterial pneumonia symptoms can vary. Some people only experience mild symptoms while others develop life-threatening complications.

According to the American Lung Association, typical symptoms of bacterial pneumonia include:

• chest pain
• shortness of breath
• a cough that may produce yellow or green mucus
• fever
• tiredness
• chills

Symptoms of bacterial pneumonia tend to be similar in both children and adults. According to the American Academy of Pediatrics, toddlers and infants may cry more than usual, have reduced energy, and appear pale.

A person who suspects symptoms of pneumonia should seek medical attention. The cause of a particular presentation of pneumonia can be difficult to determine without seeing a physician.

Since the treatments for bacterial and viral pneumonia are different, finding the correct cause is vital for choosing the appropriate treatment regimen.

Complications

Bacterial pneumonia might be complicated in both children and adults. Anyone can develop complications from bacterial pneumonia, but people with weaker immune systems, younger children, and older adults have a higher risk.

Complications may include the following:

• Respiratory failure: This might develop if oxygen levels in the lungs drop too low or if carbon dioxide levels spike. It can occur due to inadequate breathing ability, and respiratory failure may even cause lung function to stop completely.
• Sepsis: This occurs when an infection causes an overwhelming inflammatory response throughout the body. Sepsis can lead to failure in multiple organs and may be life-threatening.
• Lung abscess: This occurs when an infected pocket of pus forms in the lung.
• Empyema: This is an infectious collection of pus in the pleural cavity that surrounds the outside of lungs

Swift treatment is vital for reducing the risk of complications.

Small air sacs called alveoli are within the lobes of each lung. Normally, these air sacs aid in the body’s gas exchange, while inhaling oxygen and exhaling carbon dioxide.

When a person develops pneumonia, the air sacs experience inflammation, which can cause them to fill with fluid. If the air sacs fill with fluid rather than air, breathing might become difficult.

In some cases, the lungs and the rest of the body may not get enough oxygen.

Types

Pneumonia is often classified as either community-acquired pneumonia or hospital-acquired pneumonia. The classification refers to the location in which a person acquired the infection.

Community-acquired pneumonia is the by far more the common type. Other, less common types can occur, such as healthcare-associated pneumonia (HCAP) and ventilator-associated pneumonia (VAP).

If a person develops community-acquired pneumonia, it means infection occurred outside of a hospital. The pneumococcal bacterium usually enters the lungs after a person breathes in particles or droplets from a sneeze or cough from another individual who has the infection.

Amongst the most common causes of community-acquired pneumonia are bacteria, including Streptococcus pneumoniae, the most common bacteria, and Haemophilus influenzae.

However, viruses, including influenza viruses, can also cause community-acquired pneumonia.

Hospital-acquired pneumonia develops while in the hospital and occurs after at least 48 hours of being admitted.

Most patients with hospital-acquired pneumonia are very ill, and they become colonized with a bacterium in their mouth and/or upper respiratory tract that then enters their lungs to cause infection.

The most common causes of hospital-acquired pneumonia are Pseudomonas aeruginosa and Staphylococcus aureus.

Risk factors

Although anyone can develop bacterial pneumonia, certain factors increase the risk.

According to the Cleveland Clinic, people who have a weakened immune system as a result of cancer, cancer treatment, or an organ transplant face an increased risk of bacterial pneumonia.

Smoking tobacco products and having a long-term lung condition, such as emphysema or chronic bronchitis COPD, increases the risk. Being over 65 years of age and having had recent surgery also puts people at a higher risk.

Share on PinterestA chest X-ray can help identify areas of inflammation.

Healthcare professionals can create a diagnosis of bacterial pneumonia after completing various diagnostic tests and performing a thorough history and physical exam. During a physical exam, the doctor will listen to the lungs to determine whether they sound dysfunctional.

In most cases, a doctor will conduct a chest X-ray to check for areas of inflammation and infiltrate in the lungs.

Additional tests may also support a pneumonia diagnosis, such as a chest CT scan and an arterial blood gas (ABG) sample. An ABG measures the amount of oxygen and carbon dioxide in the arterial blood, in addition to other things like pH and bicarbonate levels, and helps determine breathing efficiency and gas exchange.

The medical team might also perform a bronchoscopy to look into the lung airways and obtain a biopsy or a mucus sample. The operating doctor inserts a small tube with a tiny camera attached through the mouth into the lungs.

A person receives medication before a bronchoscopy to numb and relax the throat, and the doctor typically also gives intravenous sedating medication.

Share on PinterestA person can receive a vaccine for pneumonia from the age of 2 months.

One of the best ways to prevent bacterial pneumonia is by preserving the strength of the immune system. Eating healthy foods, getting enough rest, and frequent hand-washing are good starting points.

Since bacterial pneumonia can develop as a complication of the flu, getting an annual flu shot may prevent pneumonia.

Two different pneumococcal vaccines are also available for reducing a person’s risk of developing bacterial pneumonia due to S. pneumoniae bacterium, the most common cause of bacterial pneumonia. These vaccines are the PCV13 and PPSV23, which protect against 13 and 23 strains of the pneumococcal bacterium respectively.

Doctors recommend that adults over 65 years of age have both types of vaccine. Children should receive a series of PCV13 vaccination starting at 2 months of age. Overall health status and age may affect the recommendation for pneumococcal vaccination.

Ultimately, a doctor will be able to determine which vaccine you may need and when to have them.

Recognizing bacterial pneumonia

In addition to bacteria, viruses and fungi can also cause pneumonia. Regardless of the cause, symptoms of pneumonia are often similar.

The similar symptoms in people with both viral and bacterial pneumonia can make determining the cause difficult.

According to the Cleveland Clinic, symptoms of bacterial pneumonia tend to be more severe than viral pneumonia and can come on suddenly. Symptoms of viral pneumonia tend to develop more slowly and are more similar to the flu at first.

One way to tell the difference between viral and bacterial pneumonia is a mucus sample, also called a sputum sample. A person coughs up a mucus sample, or a doctor obtains one from the lungs during a bronchoscopy.

A medical professional then analyzes it in the laboratory to determine the presence of any bacteria.

Supportive treatment for pneumonia, such as supplemental oxygen and fever-reducing medicine, is often the same regardless of the cause. The main difference in treatment is that antibiotics are for treating bacterial pneumonia but are ineffective for viral pneumonia.

Q:

Is bacterial pneumonia more dangerous than viral pneumonia.

A:

Depending on immune system function, either type of pneumonia could be dangerous, especially in those with a weaker immune system.

For example, if a person is an older adult and has weaker immune system functioning, a viral infection, such as influenza, may develop into viral pneumonia, or it could lead to further weakening of the immune system, in which secondary bacterial pneumonia could occur.

A person in better overall health with a better functioning immune system has a lower risk of having pneumonia in general. However, is an individual has significant or worsening symptoms that could due to any type of pneumonia, visiting a physician is the best course of action for appropriate diagnosis and treatment.

Stacy Sampson, DOAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Was this helpful?

Antibacterial therapy for nontuberculous mycobacterium lung infection in people with cystic fibrosis

This translation is out of date. Please click here for the latest English version of this review.

Non-tuberculous mycobacteria are bacteria that belong to the same group as tuberculosis bacteria and are commonly found in soil and water. These bacteria can be found in the lungs of people with cystic fibrosis and can lead to poor lung function. Although there are clinical guidelines that use antibiotics to treat lung infections caused by these bacteria, these guidelines are not designed specifically for people with cystic fibrosis. It is also not clear which antibiotics are the most effective. The main goal of this review was to determine whether the use of different combinations of antibiotics in the treatment of non-tuberculous mycobacterium infection improves lung function or reduces the incidence of chest infections in people with cystic fibrosis. We found one randomized controlled trial, but it included both people with and without CF, and we could not obtain information specifically on people with CF, so we could not include this information in the review. Until this information is available, clinicians should follow current clinical guidelines for the diagnosis and treatment of non-tuberculous mycobacteria lung infections in the general population.

Survey question

We reviewed the evidence for the use of antibiotics to treat NTB infection in people with cystic fibrosis.

Relevance

Non-tuberculous mycobacteria are bacteria that belong to the same group as tuberculosis bacteria and are commonly found in soil and water. These bacteria can be found in the lungs of people with cystic fibrosis and can lead to poor lung function. Although there are clinical guidelines that use antibiotics to treat lung infections caused by these bacteria, these guidelines are not designed specifically for people with cystic fibrosis. It is also not clear which antibiotics are most effective. The primary goal of this review was to determine whether treatment of NTB infection with different combinations of antibiotics improves lung function or reduces the incidence of chest infections in people with cystic fibrosis.

Search date

Evidence current to: 2 September 2016.

Study profile

We found one randomized controlled trial, but this included both people with and without CF, and we could not obtain information specifically on people with CF, so we could not include this information in the review.

Main results

Until data on people with CF from randomized controlled trials becomes available, clinicians should follow current clinical guidelines for the diagnosis and treatment of non-tuberculous mycobacteria lung infections in the general population.

Translation notes:

Translation: Tashtanbekova Cholpon Bolotbekovna. Editing: Yudina Ekaterina Viktorovna. Project coordination for translation into Russian: Cochrane Russia – Cochrane Russia (branch of the Northern Cochrane Center based at Kazan Federal University). For questions related to this translation, please contact us at: [email protected]; [email protected]

Pneumonia | MyPathologyReport.ca

Katerina Baranova, MD, and Matthew J. Cecchini, MD, FRCPC
May 26, 2022

What is pneumonia?

Pneumonia is an infection of the lungs caused by microorganisms such as viruses, bacteria, or fungi. Most cases of pneumonia begin when infectious particles that are inhaled through the nose and mouth travel down the respiratory tract to the lungs. Pneumonia can affect one or both lungs at the same time. The disease can affect only part of the affected lung or the whole.

What are the symptoms of pneumonia?

The most common symptoms of pneumonia include cough, fever, chills, mucus, and difficulty breathing. Other less common symptoms include confusion, chest pain, blue lips and nails, and loss of appetite. Pneumonia, like other infections, is worse in older people and people with weakened immune systems.

What are the types of pneumonia?

There are many types of pneumonia, but most are caused by bacteria or viruses. Less common types are caused by a fungus. The most common types of pneumonia will be explained in the following sections.

Bacterial pneumonia

This type of pneumonia starts when bacteria enter the lungs and alveoli, usually from the nose or mouth. Bacteria can also enter the lungs from other parts of the body through the blood. Bacteria in the alveoli will grow in the air space until they are detected by the body’s immune system, which tries to remove the bacteria from the body. To help with this process, the small capillaries surrounding the alveoli open up, increasing blood flow to the lungs. This allows more inflammatory cells including neutrophils to reach the lungs. Pathologists describe this process as acute inflammation. The green or yellow sputum produced when a person with pneumonia coughs is made up of millions of neutrophils and remnants of damaged tissue and dead bacteria. This is a sign that there is active inflammation in the lungs.

Although neutrophils are essential for killing and removing bacteria in the lungs, they can also damage the pneumocytes that line the alveoli. The combination of damaged pneumocytes with extra blood flow can lead to air spaces filling with fluid. This process is called edema. Because the fluid prevents air from entering the alveoli, a person with pneumonia may have difficulty breathing. When an x-ray or CT scan is performed, areas of the lung with infection and swelling are described as showing “consolidation”.

Once your immune system has the infection under control, specialized immune cells called macrophages will move in to clear out dead bacteria and damaged tissue. At the same time, the edematous fluid will organize itself in the air spaces and become firmer. These areas of the lung will appear gray or white on an X-ray or CT scan.

Bacterial pneumonia can be divided into lobar and bronchopneumonia. In lobar pneumonia, the bacteria have spread to cover most of a lobe of one lung. In bronchopneumonia, bacteria spread through small air spaces, affecting parts of more than one lobe of the lung. Because of this, the areas of the lung affected by bronchopneumonia are usually located near the airways.

Types of bacteria that commonly cause pneumonia include:

• Streptococcus
• Staphylococcus
• Klebsiella
• Pseudomonas
• Legionella
• Mycoplasma

Viral pneumonia

This type of pneumonia starts when viral particles enter the body, usually through the nose or mouth. The virus enters the lungs, where it infects pneumocytes or other cells in the alveoli and airways.

Viruses use specialized proteins found on their surface to attach to other proteins on the surface of lung cells. For example, SARS-CoV-2, the virus that causes Covid-19. uses a protein on its surface to attach to an angiotensin-converting enzyme 2 (ACE2) protein on lung cells. Once a virus attaches to a cell, it enters the inside of the cell, where it uses the cell’s machinery to make new copies of the virus.

Pneumocytes infected with the virus may become damaged and die. The body responds to this injury by replacing thin type 1 pneumocytes with thicker, stronger type 2 pneumocytes. Damaged pneumocytes also release signals that tell specialized virus-fighting immune cells called lymphocytes to come to the lungs. As with bacterial pneumonia, fluid fills the air spaces, making it difficult for a person with pneumonia to breathe.

Pathologists use the term hyaline membranes to describe the thick pink bands of tissue on the inner surface of the alveoli. These hyaline membranes are often found in association with type 2 pneumocytes and fluid filling the air spaces and alveolar walls. People with pneumonia have difficulty breathing because the thickened alveolar walls make it difficult for oxygen to be exchanged between the lungs and the blood. Viral pneumonia-related changes will also appear more gray or white on an x-ray or CT scan because the alveoli have less air than usual in these areas.

Types of viruses that commonly cause pneumonia include:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
• Influenza
• parainfluenza
• measles
• respiratory syncytial virus
• Cytomegaly virus
• adenovirus
• Herpes simplex virus
• Varicella zoster virus

How do pathologists diagnose pneumonia?

A pathologist can make a diagnosis of pneumonia by examining a sample of lung tissue under a microscope. A procedure in which only a small sample of tissue is removed is called a biopsy. The amount of tissue sent for microscopic examination will depend on the type of biopsy performed.

Common types of biopsy include:

• Transbronchial biopsy : A small sample of tissue is removed using forceps that are inserted through the bronchial wall into the lung.
• Cryobiopsy : A larger tissue sample is obtained by freezing a small area of ​​the lung with a tube and removing the frozen tissue from the body.
• Endobronchial biopsy : Several small tissue samples are removed using forceps to obtain tissue from inside the airways or airway walls.
• Wedge biopsy : A large piece of lung is removed by the surgeon in the operating room.

Most of the changes associated with pneumonia can be seen when tissue is stained with a combination of dyes called hematoxylin and eosin (H&E). However, to determine the type of pneumonia, your pathologist may order special stains such as Gram, Grocott (GMS), and PAS stains. Another type of test called immunohistochemistry can be ordered to look for specific types of viruses. However, the exact cause can only be determined after a tissue sample is sent to a microbiology laboratory, which has special tools to detect viruses, bacteria, and fungi.