Pneumonia
The most common infections in humans are the infections of the respiratory tract which are divided into the upper and lower respiratory tract infections. Among the infections of the respiratory tract, viral infections predominate, although bacterial infections are also common. The lower respiratory tract infections are the infections of the lung and include bronchiolitis, bronchitis, and pneumonia. At the end of the chapter there is a brief discussion of viral pneumonia in a separate paragraph.
Pneumonia is an infection of the lung parenchyma (bronchioles, alveoli, and the interstitium) associated with a newly developed radiological pulmonary shadow which may be segmental, lobar or multilobar. Pneumonias are classified as community-acquired, hospital-acquired, or as occurring in immunocompromised hosts. This classification is useful because there are differences in the pathogens, their susceptibility to antibiotics and the appropriate treatment between these three general categories.
Community-acquired pneumonia is defined as pneumonia acquired outside the hospital. The most common causes of community-acquired pneumonia include bacteria (Streptococcus pneumoniae, Haemophilus influenzae, also atypical bacteria such as Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella ), and viruses (Influenza viruses, Respiratory syncytial virus, Adenovirus, Metapneumovirus, Parainfluenza viruses, Coronaviruses).
Klebsiella pneumoniae is a rare cause of community-acquired pneumonia. It rarely causes disease in the normal host but it can cause severe pneumonia in patients with alcoholism, diabetes, or other chronic illness.
Fungi are less common causes of pneumonia, they include Histoplasma (histoplasmosis) and Coccidioides immitis (coccidioidomycosis). and less commonly Blastomyces dermatitidis (blastomycosis).
Organisms that can causes pneumonia in immunocompromised patients, such as patients with AIDS (HIV infection) or patients on immunosuppressive treatment: Pneumocystis jirovecii a fungus, previously called Pneumocystis carinii and Mycobacterium tuberculosis. Immunocompromised patients are also more susceptible to the common etiologic organisms of pneumonia such as Streptococcus pneumoniae or Hemophilus.
Staphylococcal pneumonia may occur as a complication of influenza, or in intravenous drug users, or in hospitalized patients.
Common causes of hospital-acquired pneumonia include methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, as well as Escherichia coli and other gram-negative Enterobacteriaceae (Enterobacter species, Klebsiella pneumoniae, Serratia marcescens, Proteus species, and Acinetobacter species). These bacteria are often resistant to the usual antibiotics used in the treatment of community-acquired pneumonia.
Pneumonia is an infection of the lung parenchyma (bronchioles, alveoli, and the interstitium) associated with a newly developed radiological pulmonary shadow which may be segmental, lobar or multilobar. Pneumonias are classified as community-acquired, hospital-acquired, or as occurring in immunocompromised hosts. This classification is useful because there are differences in the pathogens, their susceptibility to antibiotics and the appropriate treatment between these three general categories.
Community-acquired pneumonia is defined as pneumonia acquired outside the hospital. The most common causes of community-acquired pneumonia include bacteria (Streptococcus pneumoniae, Haemophilus influenzae, also atypical bacteria such as Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella ), and viruses (Influenza viruses, Respiratory syncytial virus, Adenovirus, Metapneumovirus, Parainfluenza viruses, Coronaviruses).
Klebsiella pneumoniae is a rare cause of community-acquired pneumonia. It rarely causes disease in the normal host but it can cause severe pneumonia in patients with alcoholism, diabetes, or other chronic illness.
Fungi are less common causes of pneumonia, they include Histoplasma (histoplasmosis) and Coccidioides immitis (coccidioidomycosis). and less commonly Blastomyces dermatitidis (blastomycosis).
Organisms that can causes pneumonia in immunocompromised patients, such as patients with AIDS (HIV infection) or patients on immunosuppressive treatment: Pneumocystis jirovecii a fungus, previously called Pneumocystis carinii and Mycobacterium tuberculosis. Immunocompromised patients are also more susceptible to the common etiologic organisms of pneumonia such as Streptococcus pneumoniae or Hemophilus.
Staphylococcal pneumonia may occur as a complication of influenza, or in intravenous drug users, or in hospitalized patients.
Common causes of hospital-acquired pneumonia include methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, as well as Escherichia coli and other gram-negative Enterobacteriaceae (Enterobacter species, Klebsiella pneumoniae, Serratia marcescens, Proteus species, and Acinetobacter species). These bacteria are often resistant to the usual antibiotics used in the treatment of community-acquired pneumonia.
Symptoms and signs of pneumonia
Pneumonia usually manifests with fever, chills, rigors, malaise, and cough (usually productive cough, i.e. with sputum) and often pleuritic chest pain. There is often dyspnea (shortness of breath), tachypnea (> 20 breaths per minute), and tachycardia. When the patient appears distressed due to dyspnea, has tachypnea > 25/minute, or manifests cyanosis, confusion, or hypotension, these are indications of a severe condition.Symptoms may be less impressive in immunocompromised states ( HIV, chronic alcoholism), in the elderly [occasionally in the elderly, pneumonia manifests only with confusion and/or drowsiness (sleepiness)] and in diabetics.
Auscultation of the thorax in pneumonia, especially in the presence of consolidation, may reveal reduced lung sounds, crackles, and/or bronchial breathing and increased tactile (vocal) fremitus, or increased vocal resonance (bronchophony and whispered pectoriloquy) over the diseased portion of the lung. For an explanation of these physical signs see below:
Bronchial breath sounds are normally heard only on areas near the carina and the mainstem bronchi: over the manubrium of the sternum. Also anteriorly in the first and second pleural interspaces and posteriorly between the scapulae (in these areas they are called bronchovesicular sounds, a mixture of bronchial and vesicular sounds). If they are heard in other areas they are abnormal and then the most common cause is a pneumonia (consolidation of an area of the lung). ( Less common situations where bronchial sounds are heard: collapsed lung adjacent to a pleural effusion, over an area of localized fibrosis, or cavitation, or a mass being in contact with large airways). Bronchial sounds have an expiratory phase which is equal or longer in duration than the inspiratory phase and between these two phases, there is a short pause. They are loud sounds like blowing through a tube. Note that the normal sounds heard over the lung parenchyma (except the sites mentioned above) are the vesicular sounds. Vesicular sounds are soft (of lower intensity than bronchial sounds) with a low pitch and are characterized by an inspiratory phase which is longer and louder than the expiratory phase and without a pause between them. Click on this link to listen to vesicular and bronchial breath sounds https://www.easyauscultation.com/bronchial-breath-sounds
Crackles (also called rales or crepitations) are short interrupted nonmusical abnormal lung sounds perceived as discontinuous clicking or rattling sounds. Crackles can sound like salt dropped onto a hot pan or like cellophane being crumpled or like rubbing hair next to one's ear. In this link, you can listen to crackles
https://www.easyauscultation.com/crackles-lung-sounds.On the other hand, other abnormal sounds are the musical sounds: Wheezes and rhonchi. These are continuous musical sounds heard mostly during expiration. They are produced by air flow through narrowed bronchi. Wheezes are high pitched, whereas rhonchi are low pitched (like moaning). Therefore rhonchi are also known as low pitched wheezes. Musical sounds can be heard in asthma, chronic obstructive pulmonary disease (COPD), bronchitis, atypical pneumonia, or a foreign body or a tumor causing stenosis of the lumen of a bronchus. Listen to various lung sounds LINK https://www.easyauscultation.com/lung-sounds-reference-guideTactile or vocal fremitus is palpation of the chest wall to detect the intensity of vibrations created with certain spoken words in a constant tone and voice. Comparing the intensity of the palpated vibrations on different areas of the chest between both sides can provide indications of underlying lung pathology. Inflammation and consolidation create a dense medium which increases the transmission of tactile fremitus, therefore in these situations the intensity of the palpated vocal vibrations is increased. On the other hand, tactile fremitus is decreased in asthma, emphysema (due to air trapping that decreases the density of lung parenchyma), pneumothorax, pleural effusion and obesity (due to the interposed air, fluid or fat respectively).
Bronchophony: A louder sound heard over an area of consolidation.
Whispering pectoriloquy: The patient is whispering "one, two, three", while the examiner auscultates over the lung fields. If whispered words are heard clearly over an area of the lung this is suggestive of the presence of consolidation.
Whispering pectoriloquy: The patient is whispering "one, two, three", while the examiner auscultates over the lung fields. If whispered words are heard clearly over an area of the lung this is suggestive of the presence of consolidation.
Egophony is an "E to A" change: On auscultation, there is a qualitative change in the voice that resembles the bleating of a goat. When the sound of the vowel "E" is distorted so that it is perceived by the examiner as "A" or "AAAH." Egophony is also a sign suggestive of a consolidation.
Crackles can be heard in pneumonia. Bilateral crackles can be heard in congestive heart failure and in interstitial lung disease (pulmonary fibrosis).
In pneumonia, percussion over the affected area of the lung may reveal dullness.
On the basis of the symptoms and clinical signs, pneumonia can be classified as typical and atypical.
The classic presentation of typical bacterial pneumonia (which is caused by bacteria such as Streptococcus pneumonia which is the most common cause, Klebsiella, Staphylococcus aureus, Hemophilus and Moraxella catarrhalis) is the abrupt onset of fever and chills, productive cough with purulent sputum, and pleuritic chest pain. Tachypnea and tachycardia are usually present. Examination of the chest may reveal signs of consolidation, such as dullness to percussion, coarse crackles, bronchial breath sounds, or increased tactile fremitus and increased vocal resonance (bronchophony, egophony).
The atypical pneumonia syndrome is caused by viruses and other organisms such as Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella. The patient presents with a subacute onset of systemic symptoms, such as fever, headache, malaise, and myalgias, associated with cough that is often nonproductive, although it may also be productive (with sputum). Physical signs usually include scattered rhonchi or coarse crackles or both. Signs of consolidation are less common.
Laboratory testing in pneumonia reveals leukocytosis, and an elevated erythrocyte sedimentation rate (ESR) and CRP. Leukocytosis with an elevated neutrophil count suggests a bacterial cause of lung infection. (ESR and CRP are usually elevated in inflammatory and infectious disease, but they are non-specific tests).
Sputum samples are obtained for Gram stain, culture, and antimicrobial sensitivity testing.
The chest X-ray in pneumonia will demonstrate an infiltrate seen as a shadow (white or gray area on the image), referred to as an opacity or consolidation, which usually does not have well-defined borders (ill-defined opacity). The opacity can be homogeneous or non-homogeneous and (in contrast to atelectasis) there is no lung volume loss. A sign which is often present is air bronchogram, (i.e. bronchi containing air, seen as black thin tubular structures inside the shadow). Depending on the location of the opacity, the silhouette sign can be present (when the opacity hides part of the border between the lung and the heart or the diaphragm, i.e. the border of an adjacent structure is not clear). Occasionally a pleural effusion may complicate pneumonia (parapneumonic effusion).
Also see this link Pneumonia-Chest X-ray-University of Virginia introduction to chest radiology
Diagnosis of this chest X-ray?
Pneumonia of the right lung (there is a shadow-an ill-defined opacity- in the lower lung field indicating an infiltrate) and a loculated parapneumonic pleural effusion. ( Courtesy of Dr. Naser Salam)
According to the CURB-65 rule when 2 or more of the following factors are present, the patient requires hospitalization:
• Confusion
• Urea > 30 mg/dl
• Respiratory rate > 30/min
• Blood pressure: reduced (systolic < 90 mmHg or diastolic < 60 mmHg)
• Age > 65 years
The ATS modified criteria include:
The major criteria:
A need for mechanical ventilation or
A need for vasopressors (septic shock)
Crackles can be heard in pneumonia. Bilateral crackles can be heard in congestive heart failure and in interstitial lung disease (pulmonary fibrosis).
In pneumonia, percussion over the affected area of the lung may reveal dullness.
On the basis of the symptoms and clinical signs, pneumonia can be classified as typical and atypical.
The classic presentation of typical bacterial pneumonia (which is caused by bacteria such as Streptococcus pneumonia which is the most common cause, Klebsiella, Staphylococcus aureus, Hemophilus and Moraxella catarrhalis) is the abrupt onset of fever and chills, productive cough with purulent sputum, and pleuritic chest pain. Tachypnea and tachycardia are usually present. Examination of the chest may reveal signs of consolidation, such as dullness to percussion, coarse crackles, bronchial breath sounds, or increased tactile fremitus and increased vocal resonance (bronchophony, egophony).
The atypical pneumonia syndrome is caused by viruses and other organisms such as Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella. The patient presents with a subacute onset of systemic symptoms, such as fever, headache, malaise, and myalgias, associated with cough that is often nonproductive, although it may also be productive (with sputum). Physical signs usually include scattered rhonchi or coarse crackles or both. Signs of consolidation are less common.
Laboratory tests and imaging for the diagnosis of pneumonia
Hemoglobin oxygen saturation should be measured with pulse oximetry or examination of arterial blood gases. Abnormal is a resting hemoglobin oxygen saturation < 95%.Laboratory testing in pneumonia reveals leukocytosis, and an elevated erythrocyte sedimentation rate (ESR) and CRP. Leukocytosis with an elevated neutrophil count suggests a bacterial cause of lung infection. (ESR and CRP are usually elevated in inflammatory and infectious disease, but they are non-specific tests).
Sputum samples are obtained for Gram stain, culture, and antimicrobial sensitivity testing.
The chest X-ray in pneumonia will demonstrate an infiltrate seen as a shadow (white or gray area on the image), referred to as an opacity or consolidation, which usually does not have well-defined borders (ill-defined opacity). The opacity can be homogeneous or non-homogeneous and (in contrast to atelectasis) there is no lung volume loss. A sign which is often present is air bronchogram, (i.e. bronchi containing air, seen as black thin tubular structures inside the shadow). Depending on the location of the opacity, the silhouette sign can be present (when the opacity hides part of the border between the lung and the heart or the diaphragm, i.e. the border of an adjacent structure is not clear). Occasionally a pleural effusion may complicate pneumonia (parapneumonic effusion).
Also see this link Pneumonia-Chest X-ray-University of Virginia introduction to chest radiology
Diagnosis of this chest X-ray?
Pneumonia of the right lung (there is a shadow-an ill-defined opacity- in the lower lung field indicating an infiltrate) and a loculated parapneumonic pleural effusion. ( Courtesy of Dr. Naser Salam)
Assessment of pneumonia severity
The decision if the patient with community-acquired pneumonia will be treated in the hospital or as an outpatient depends on the presence or absence of indications suggestive of severe disease. Two scoring systems may aid in this decision, the CURB-65 rule and American Thoracic Society (ATS) modified criteria. These scoring systems can be helpful but they should not replace the physician's clinical judgment. In general a respiratory rate of > 25 breaths/minute or hemoglobin oxygen saturation <92% should cause serious concern.According to the CURB-65 rule when 2 or more of the following factors are present, the patient requires hospitalization:
• Confusion
• Urea > 30 mg/dl
• Respiratory rate > 30/min
• Blood pressure: reduced (systolic < 90 mmHg or diastolic < 60 mmHg)
• Age > 65 years
The ATS modified criteria include:
The major criteria:
A need for mechanical ventilation or
A need for vasopressors (septic shock)
A patient having one of the major criteria will need admission to an intensive care unit (ICU)
The minor criteria:
Respiratory rate > 30/min,
PaO2/FIO2 < 250,
Bilateral or multilobar infiltrates on chest X-ray
The minor criteria:
Respiratory rate > 30/min,
PaO2/FIO2 < 250,
Bilateral or multilobar infiltrates on chest X-ray
At least one major or two minor criteria present on the ATS criteria define severe pneumonia, which requires treatment in the ICU. The presence of one of the minor criteria is an indication for hospitalization in the ward.
Treatment of pneumonia depends on the most probable causative organisms. The probable organisms are associated with the context in which pneumonia develops, thus pneumonias are classified as community-acquired, hospital-acquired, or as occurring in immunocompromised hosts.
Treatment includes
1 ) General measures such as administration of oxygen (indicated in patients with tachypnea or a low arterial oxygen saturation) and the maintenance of fluid balance (intravenous fluids are usually administered to those with severe illness and to older patients, while in most other patients an adequate oral fluid intake should be encouraged.) A temporary discontinuation or reduction in the dosage of antihypertensive medications will be appropriate in patients with hypotension or dehydration.
2 ) Specific measures: Appropriate antibiotic treatment. Oral antibiotics are usually adequate for patients without signs of a severe clinical condition. Therefore, for outpatients antibiotics are administered PO (by the oral route). Patients with indications of severe pneumonia or impaired consciousness will require intravenous antibiotics. Therefore, for patients admitted to the hospital intravenous (IV) antibiotic treatment is employed which should be switched to PO administration when clinical stability is achieved. The duration of antibiotic treatment depends on disease severity and usually ranges from about 7 to 15 days.
Antibiotic treatment for community-acquired pneumonia:
In general, an effective treatment covering the most probable bacterial pathogens is a combination of a beta-lactam (e.g. amoxicillin, or amoxicillin with clavulanate, or a cephalosporin) plus a macrolide (e.g. clarithromycin or erythromycin). Another option is the administration of a single antibiotic such as a macrolide or doxycycline. For patients with comorbidities a fluoroquinolone is often administered (e.g. levofloxacin or moxifloxacin).
Treatment of pneumonia depends on the most probable causative organisms. The probable organisms are associated with the context in which pneumonia develops, thus pneumonias are classified as community-acquired, hospital-acquired, or as occurring in immunocompromised hosts.
Treatment includes
1 ) General measures such as administration of oxygen (indicated in patients with tachypnea or a low arterial oxygen saturation) and the maintenance of fluid balance (intravenous fluids are usually administered to those with severe illness and to older patients, while in most other patients an adequate oral fluid intake should be encouraged.) A temporary discontinuation or reduction in the dosage of antihypertensive medications will be appropriate in patients with hypotension or dehydration.
2 ) Specific measures: Appropriate antibiotic treatment. Oral antibiotics are usually adequate for patients without signs of a severe clinical condition. Therefore, for outpatients antibiotics are administered PO (by the oral route). Patients with indications of severe pneumonia or impaired consciousness will require intravenous antibiotics. Therefore, for patients admitted to the hospital intravenous (IV) antibiotic treatment is employed which should be switched to PO administration when clinical stability is achieved. The duration of antibiotic treatment depends on disease severity and usually ranges from about 7 to 15 days.
Antibiotic treatment for community-acquired pneumonia:
In general, an effective treatment covering the most probable bacterial pathogens is a combination of a beta-lactam (e.g. amoxicillin, or amoxicillin with clavulanate, or a cephalosporin) plus a macrolide (e.g. clarithromycin or erythromycin). Another option is the administration of a single antibiotic such as a macrolide or doxycycline. For patients with comorbidities a fluoroquinolone is often administered (e.g. levofloxacin or moxifloxacin).
For patients with uncomplicated community-acquired pneumonia
Amoxicillin 500-1000 mg x 3 times /day orally (PO)
For patients allergic to penicillin
Clarithromycin 500 mg x 2, or Erythromycin 500 mg x 4 PO/day.
For patients with comorbidities or antibiotic use in the past three months, it is preferable to administer :
either a beta-lactam (e.g., amoxicillin with clavulanate) plus a macrolide
or a fluoroquinolone (levofloxacin or moxifloxacin).
If Mycoplasma or Legionella is suspected
Clarithromycin 500 mg x 2 PO or intravenously (IV)
or Erythromycin 500 mg x4 times day /PO. In severe cases, Rifampicin 600 mg x 2/day IV is added to clarithromycin or erythromycin.
If Staphylococcus is cultured or suspected, a usual choice is Flucloxacillin 1-2 g x 4 times/ day IV.
In severe community-acquired pneumonia choices include:
Severe CAP
• Clarithromycin 500 mg x2 IV or Erythromycin 500 mg x 4 IV in combination with
Co-amoxiclav 1.2 g x 3 IV or Ceftriaxone 1-2 g IV /day or Cefuroxime 1.5 g x 3 /day IV or
• Amoxicillin 1g x 4 IV plus flucloxacillin 2 g x4 IV/day
For the treatment of hospital-acquired pneumonia see the LINK:
MSD Manual-Hospital acquired pneumonia
Generally, influenza type A is the most common cause of viral pneumonia. Influenza type A and type B can be prevented by vaccination (every year) In fact, influenza is the only respiratory virus preventable by vaccination.
Currently, there is a growing concern about coronaviruses, because of the COVID-19 pandemic. Coronaviruses are a large family of viruses that may cause illness in animals or humans. In humans, several coronaviruses are known causes of respiratory infections ranging from a mild viral upper respiratory tract infection with symptoms of the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The most recently discovered coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) causes coronavirus disease 2019 (COVID-19) which has currently evolved to a pandemic.
The usual route of transmission of viral respiratory infections is by respiratory droplets and close contact, or by touching a contaminated surface and then the face with unwashed hands.
As mentioned above, the influenza virus generally is the most common cause of viral pneumonia. It can often be complicated by bacterial pneumonia caused by Streptococcus pneumoniae, Hemophilus influenzae or Staphylococcus aureus because it compromises the defense of the respiratory system against bacteria.
Physical findings may include fever, scattered rhonchi or crackles (rales) and diminished breath sounds whereas tachypnea (with >20 breaths/minute which is abnormal) may also be present. A respiratory rate > 25/minute, heart rate > 120 beats per minute, or hemoglobin oxygen saturation (SatO2)< 92 % should cause serious concern. Often in viral pneumonia, there is a low temperature elevation and absent or mild findings on lung auscultation disproportionate to the level of tachypnea and tachycardia and to the severity of dyspnea. Therefore caution is needed not to underestimate the severity of dyspnea when the auscultatory findings seem unimportant. As mentioned above scattered rhonchi or crackles are often present, whereas signs of consolidation are uncommon. (For a description of rhonchi and crackles see above in this page, in the paragraph "symptoms and signs of pneumonia").
Regarding COVID-19 (coronavirus disease 2019), the most common symptoms are fever, tiredness, and dry cough. Some patients may have nasal congestion, rhinorrhea, sore throat or diarrhea. These symptoms are usually mild and begin gradually. Some people become infected without the development of any symptoms (asymptomatic carriers of the virus). Most patients (about 80%) experience a mild infection and recover spontaneously from the disease without needing special treatment. A more serious infection with dyspnea manifests in about 1 out of every 6 people with the COVID-19 infection. The overall rate of deaths per number of diagnosed patients is about 4%. Patients with a higher risk to develop a serious infection with manifestations of viral pneumonia are those of age > 65 years and patients with underlying medical conditions such as heart failure, chronic obstructive pulmonary disease (COPD), diabetes, or immunocompromised patients.
Radiologic studies in many patients show poorly defined nodules, 4-10 mm in diameter, and patchy areas of peribronchial ground-glass opacity or patchy areas of peribronchial consolidation. In the early stages of viral pneumonia chest X-rays in many cases show only subtle or no findings, whereas chest CT scans have a higher sensitivity and they may show bilateral asymmetric ground-glass lesions early in the course of the disease.
In more severe cases, the chest radiograph shows the confluence of patchy, bilateral (or less often unilateral) ground-glass appearance and consolidations. In summary, important findings on the chest X-ray or chest CT scan may have the form of ground glass appearance in the early stages or the form of areas with opacity (infiltrates) or the form of interstitial infiltrates. The ground glass appearance is an increased density (a hazy gray appearance) in one or more areas of the lung. The difference of ground glass appearance from an opacity is that in the former the pulmonary vessels are still visible whereas in an opacity there is a more prominent increase in the density of the radiological appearance of the affected lung (a more white appearance), such that the vessels cannot be seen. The above lesions can be patchy or diffuse. In extremely severe cases there is a clinical and radiologic picture of ARDS (adult respiratory distress syndrome).
When the clinical manifestations are suggestive of possible viral pneumonia and/ or the chest X-ray or chest CT shows infiltrates, usually laboratory testing for influenza, coronavirus COVID-19, or other viruses is performed. For the laboratory diagnosis Polymerase chain reaction (PCR and RT-PCR) technology is replacing viral cultures. For some viruses serial viral antibody titers are also used in the diagnosis.
A male, age 75 who was admitted to the hospital. On presentation, he had fever, cough, dyspnea and tachypnea and reduced hemoglobin-oxygen saturation. What are the findings on his chest X-ray ?
Extensive bilateral ground-glass areas suggestive of severe viral pneumonia. Notice that an endotracheal tube and an internal jugular venous catheter is also present. This patient was found positive for COVID-19. The causative agent, SARS-CoV-2, a coronavirus is spreading throughout the world. Case courtesy of Dr Fabio Macori, <ahref="https://radiopaedia.org/">Radiopaedia.org</a>. From the case <a href="https://radiopaedia.org/cases/74867">rID: 74867</a>
LINK https://radiopaedia.org/cases/covid-19-pneumonia-12?lang=us
High-resolution chest CT (HRCT) from a patient with viral pneumonia caused by COVID-19 infection. The image is from a 38 years old male with fever, dry cough, and dyspnea. Laboratory tests showed a normal total WBC count with a reduced lymphocyte count and elevated c-reactive protein (CRP), which is a nonspecific marker of inflammation.
Multiple patchy infiltrates with a ground-glass appearance. Thickening of interlobular septa.
Amoxicillin 500-1000 mg x 3 times /day orally (PO)
For patients allergic to penicillin
Clarithromycin 500 mg x 2, or Erythromycin 500 mg x 4 PO/day.
For patients with comorbidities or antibiotic use in the past three months, it is preferable to administer :
either a beta-lactam (e.g., amoxicillin with clavulanate) plus a macrolide
or a fluoroquinolone (levofloxacin or moxifloxacin).
If Mycoplasma or Legionella is suspected
Clarithromycin 500 mg x 2 PO or intravenously (IV)
or Erythromycin 500 mg x4 times day /PO. In severe cases, Rifampicin 600 mg x 2/day IV is added to clarithromycin or erythromycin.
If Staphylococcus is cultured or suspected, a usual choice is Flucloxacillin 1-2 g x 4 times/ day IV.
In severe community-acquired pneumonia choices include:
Severe CAP
• Clarithromycin 500 mg x2 IV or Erythromycin 500 mg x 4 IV in combination with
Co-amoxiclav 1.2 g x 3 IV or Ceftriaxone 1-2 g IV /day or Cefuroxime 1.5 g x 3 /day IV or
• Amoxicillin 1g x 4 IV plus flucloxacillin 2 g x4 IV/day
For the treatment of hospital-acquired pneumonia see the LINK:
MSD Manual-Hospital acquired pneumonia
Viral Pneumonia
Viral pneumonia is a lung infection caused by a virus. As mentioned above the most common viruses involved include Influenza viruses, Respiratory syncytial virus, Adenovirus, Metapneumovirus, Parainfluenza viruses, and Coronaviruses.Generally, influenza type A is the most common cause of viral pneumonia. Influenza type A and type B can be prevented by vaccination (every year) In fact, influenza is the only respiratory virus preventable by vaccination.
Currently, there is a growing concern about coronaviruses, because of the COVID-19 pandemic. Coronaviruses are a large family of viruses that may cause illness in animals or humans. In humans, several coronaviruses are known causes of respiratory infections ranging from a mild viral upper respiratory tract infection with symptoms of the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The most recently discovered coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) causes coronavirus disease 2019 (COVID-19) which has currently evolved to a pandemic.
The usual route of transmission of viral respiratory infections is by respiratory droplets and close contact, or by touching a contaminated surface and then the face with unwashed hands.
As mentioned above, the influenza virus generally is the most common cause of viral pneumonia. It can often be complicated by bacterial pneumonia caused by Streptococcus pneumoniae, Hemophilus influenzae or Staphylococcus aureus because it compromises the defense of the respiratory system against bacteria.
The symptoms and clinical findings of viral pneumonia
The symptoms are similar to those of bacterial pneumonia because they include cough, fever, malaise and often dyspnea (shortness of breath-SOB). Additionally, the following symptoms are commonly present and often raise a suspicion of a viral etiology: rhinitis (nasal congestion and nasal discharge), myalgias (generalized muscle aches), a sore throat, and headache. Gradual onset of symptoms, fever of lower grade, concomitant flu-like symptoms (such as rhinitis and diffuse myalgias) or concomitant gastrointestinal symptoms suggest that a viral infection is more probable than a bacterial one. These are only clues and do not provide certainty.Physical findings may include fever, scattered rhonchi or crackles (rales) and diminished breath sounds whereas tachypnea (with >20 breaths/minute which is abnormal) may also be present. A respiratory rate > 25/minute, heart rate > 120 beats per minute, or hemoglobin oxygen saturation (SatO2)< 92 % should cause serious concern. Often in viral pneumonia, there is a low temperature elevation and absent or mild findings on lung auscultation disproportionate to the level of tachypnea and tachycardia and to the severity of dyspnea. Therefore caution is needed not to underestimate the severity of dyspnea when the auscultatory findings seem unimportant. As mentioned above scattered rhonchi or crackles are often present, whereas signs of consolidation are uncommon. (For a description of rhonchi and crackles see above in this page, in the paragraph "symptoms and signs of pneumonia").
Regarding COVID-19 (coronavirus disease 2019), the most common symptoms are fever, tiredness, and dry cough. Some patients may have nasal congestion, rhinorrhea, sore throat or diarrhea. These symptoms are usually mild and begin gradually. Some people become infected without the development of any symptoms (asymptomatic carriers of the virus). Most patients (about 80%) experience a mild infection and recover spontaneously from the disease without needing special treatment. A more serious infection with dyspnea manifests in about 1 out of every 6 people with the COVID-19 infection. The overall rate of deaths per number of diagnosed patients is about 4%. Patients with a higher risk to develop a serious infection with manifestations of viral pneumonia are those of age > 65 years and patients with underlying medical conditions such as heart failure, chronic obstructive pulmonary disease (COPD), diabetes, or immunocompromised patients.
Radiological findings in viral pneumonia
Chest radiography in patients with viral pneumonia often demonstrates bilateral lung involvement, but radiological findings are never pathognomonic for the virus type.Radiologic studies in many patients show poorly defined nodules, 4-10 mm in diameter, and patchy areas of peribronchial ground-glass opacity or patchy areas of peribronchial consolidation. In the early stages of viral pneumonia chest X-rays in many cases show only subtle or no findings, whereas chest CT scans have a higher sensitivity and they may show bilateral asymmetric ground-glass lesions early in the course of the disease.
In more severe cases, the chest radiograph shows the confluence of patchy, bilateral (or less often unilateral) ground-glass appearance and consolidations. In summary, important findings on the chest X-ray or chest CT scan may have the form of ground glass appearance in the early stages or the form of areas with opacity (infiltrates) or the form of interstitial infiltrates. The ground glass appearance is an increased density (a hazy gray appearance) in one or more areas of the lung. The difference of ground glass appearance from an opacity is that in the former the pulmonary vessels are still visible whereas in an opacity there is a more prominent increase in the density of the radiological appearance of the affected lung (a more white appearance), such that the vessels cannot be seen. The above lesions can be patchy or diffuse. In extremely severe cases there is a clinical and radiologic picture of ARDS (adult respiratory distress syndrome).
When the clinical manifestations are suggestive of possible viral pneumonia and/ or the chest X-ray or chest CT shows infiltrates, usually laboratory testing for influenza, coronavirus COVID-19, or other viruses is performed. For the laboratory diagnosis Polymerase chain reaction (PCR and RT-PCR) technology is replacing viral cultures. For some viruses serial viral antibody titers are also used in the diagnosis.
A male, age 75 who was admitted to the hospital. On presentation, he had fever, cough, dyspnea and tachypnea and reduced hemoglobin-oxygen saturation. What are the findings on his chest X-ray ?
Extensive bilateral ground-glass areas suggestive of severe viral pneumonia. Notice that an endotracheal tube and an internal jugular venous catheter is also present. This patient was found positive for COVID-19. The causative agent, SARS-CoV-2, a coronavirus is spreading throughout the world. Case courtesy of Dr Fabio Macori, <ahref="https://radiopaedia.org/">Radiopaedia.org</a>. From the case <a href="https://radiopaedia.org/cases/74867">rID: 74867</a>
LINK https://radiopaedia.org/cases/covid-19-pneumonia-12?lang=us
High-resolution chest CT (HRCT) from a patient with viral pneumonia caused by COVID-19 infection. The image is from a 38 years old male with fever, dry cough, and dyspnea. Laboratory tests showed a normal total WBC count with a reduced lymphocyte count and elevated c-reactive protein (CRP), which is a nonspecific marker of inflammation.
Multiple patchy infiltrates with a ground-glass appearance. Thickening of interlobular septa.
The image is from:
Licensed under the Creative Commons Attribution 4.0 International license.
| Source | https://mmrjournal.biomedcentral.com/articles/10.1186/s40779-020-0233-6 |
| Author | Jin, Y., Cai, L., Cheng, Z. et a |
Severity assessment in viral pneumonia
A variety of studies concerning respiratory viruses have demonstrated risk factors for adverse prognosis by multivariate regression. In general, the risk scores used for community-acquired pneumonia can also be employed for viral pneumonia. Risk factors found to be especially important for severity assessment in viral pneumonia and are associated with a severe prognosis are the following: age > 70 years, serious comorbid conditions, PO2/FiO2 ≤ 250 , lymphopenia (peripheral blood lymphocyte count <0.8∗109/L) and chest CT findings of multilobular infiltrates (multilobular infection).Treatment of viral pneumonia (general principles)
Supportive care includes rest, adequate hydration, oxygen and inhaled beta-agonists (when hypoxemia, dyspnea or tachypnea is present), antipyretics or analgesics as needed (although a moderate grade of fever probably is beneficial for the defense against the virus and may not need treatment with antipyretics) and adequate nutrition and close observation. Some patients will need intravenous fluids. In case of respiratory failure, endotracheal intubation and mechanical ventilation will be needed to support the patient.
To avoid the spread of the infection necessary steps include isolation of the patient and protective measures for the health care personnel.
Protective measures for the personnel include:
Personal protective equipment (PPE) such as gown, mask or respirator, goggles or face-shield and gloves (see Link: https://www.cdc.gov/hai/pdfs/ppe/PPE-Sequence.pdf), hand hygiene with alcohol-based hand rub before and after patient contact, contact with potentially infectious material, and before putting on and upon removal of PPE, including gloves
Placing a facemask on the patient may be needed
Preventive measures depend on the clinical situation and the degree of suspicion of a highly contagious virus, especially if there is an epidemic.
Specific antiviral treatment depends on the virus type and includes the following:
For Influenza pneumonia: Oseltamivir or Peramivir or Zanamivir
Usually, Oseltamivir is administered (Dosage: 75 mg x 2/day for 5 days) The patient with influenza should be observed for signs of secondary bacterial infection which may occasionally develop. In such cases, antibiotic treatment must be added.
For Respiratory Syncytial Virus (RSV) pneumonia: Ribavirin
For Parainfluenza virus: Ribavirin
To avoid the spread of the infection necessary steps include isolation of the patient and protective measures for the health care personnel.
Protective measures for the personnel include:
Personal protective equipment (PPE) such as gown, mask or respirator, goggles or face-shield and gloves (see Link: https://www.cdc.gov/hai/pdfs/ppe/PPE-Sequence.pdf), hand hygiene with alcohol-based hand rub before and after patient contact, contact with potentially infectious material, and before putting on and upon removal of PPE, including gloves
Placing a facemask on the patient may be needed
Preventive measures depend on the clinical situation and the degree of suspicion of a highly contagious virus, especially if there is an epidemic.
Specific antiviral treatment depends on the virus type and includes the following:
For Influenza pneumonia: Oseltamivir or Peramivir or Zanamivir
Usually, Oseltamivir is administered (Dosage: 75 mg x 2/day for 5 days) The patient with influenza should be observed for signs of secondary bacterial infection which may occasionally develop. In such cases, antibiotic treatment must be added.
For Respiratory Syncytial Virus (RSV) pneumonia: Ribavirin
For Parainfluenza virus: Ribavirin
For Adenovirus: Ribavirin
For Measles virus: Ribavirin
For Cytomegalovirus: Ganciclovir
For COVID-19 viral pneumonia (coronavirus SARS-CoV2): This is an enveloped RNA virus. Treatment is supportive (as outlined above for viral pneumonia in general). There is yet no specific treatment with proven efficacy. Several existing medications are currently being evaluated for the treatment of COVID-19. In March 2020, WHO launched a multi-country trial called "Solidarity"to evaluate medications for the treatment of COVID-19. Such experimental treatments being researched under "Solidarity trial" include remdesivir, chloroquine, hydroxychloroquine, ritonavir/lopinavir and ritonavir/lopinavir combined with interferon beta.
For COVID-19 viral pneumonia (coronavirus SARS-CoV2): This is an enveloped RNA virus. Treatment is supportive (as outlined above for viral pneumonia in general). There is yet no specific treatment with proven efficacy. Several existing medications are currently being evaluated for the treatment of COVID-19. In March 2020, WHO launched a multi-country trial called "Solidarity"to evaluate medications for the treatment of COVID-19. Such experimental treatments being researched under "Solidarity trial" include remdesivir, chloroquine, hydroxychloroquine, ritonavir/lopinavir and ritonavir/lopinavir combined with interferon beta.
For more information about COVID-19 diagnosis and management read these articles (Links are provided):
Hassan S, Sheikh F N, Jamal S, et al. (March 21, 2020) Coronavirus (COVID-19): A Review of Clinical Features, Diagnosis, and Treatment. Cureus 2020; 12(3): e7355. doi:10.7759/cureus.7355
Hassan S, Sheikh F N, Jamal S, et al. (March 21, 2020) Coronavirus (COVID-19): A Review of Clinical Features, Diagnosis, and Treatment. Cureus 2020; 12(3): e7355. doi:10.7759/cureus.7355
LINK Coronavirus (COVID-19): A Review of Clinical Features, Diagnosis, and Treatment. Cureus 2020
Bibliography
Mantero M, Tarsia P, et al.. Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations. Multidiscip Respir Med. 2017;12:26. doi:10.1186/s40248-017-0106-3
LINK Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations
Kaysin A, Viera AJ. Community-Acquired Pneumonia in Adults: Diagnosis and Management. Am Fam Physician. 2016;94(9):698-706
Freeman AM, Leigh, Jr TR. Viral Pneumonia. [Updated 2019 Dec 25]. In: StatPearls Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513286
Modi P, Tolat S. Vocal Fremitus. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499838/
Jin, Y., Cai, L., Cheng, Z. et al. A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumoniaMilitary Med Res 2020; 7(4) . https://doi.org/10.1186/s40779-020-0233-6
Jin, Y., Cai, L., Cheng, Z. et al. A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumoniaMilitary Med Res 2020; 7(4) . https://doi.org/10.1186/s40779-020-0233-6
Emergency medicine free book -Back to Home-page and table of contents
Back to the chapter Dyspnea, Respiratory failure, and assisted ventilation
Back to the chapter Dyspnea, Respiratory failure, and assisted ventilation
Bibliography
Mantero M, Tarsia P, et al.. Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations. Multidiscip Respir Med. 2017;12:26. doi:10.1186/s40248-017-0106-3
LINK Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations
Kaysin A, Viera AJ. Community-Acquired Pneumonia in Adults: Diagnosis and Management. Am Fam Physician. 2016;94(9):698-706
LINK https://www.aafp.org/afp/2016/1101/p698.html
Sunjay Sethy Community acquired pneumonia in the MSD Manual Professional Version
LINK Community acquired pneumonia
Sunjay Sethy Community acquired pneumonia in the MSD Manual Professional Version
LINK Community acquired pneumonia
Freeman AM, Leigh, Jr TR. Viral Pneumonia. [Updated 2019 Dec 25]. In: StatPearls Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513286
LINK Viral pneumonia
Meddean.luc.edu Breath sounds Link http://www.meddean.luc.edu/lumen/MedEd/medicine/pulmonar/pd/b-sounds.htm
LINK Vocal or tactile fremitus and vocal resonance
Figueiredo, Luiz Tadeu Moraes. (2009). Viral pneumonia: epidemiological, clinical, pathophysiological and therapeutic aspects. Jornal Brasileiro de Pneumologia, 2009;35(9): 899-906.
LINK Viral pneumonia
Jin, Y., Cai, L., Cheng, Z. et al. A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumoniaMilitary Med Res 2020; 7(4) . https://doi.org/10.1186/s40779-020-0233-6
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