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Terms in this set (127)
Give the definition of bacterial pneumonia.
Acute inflammation and consolidation of the lung due to a bacterial agent.
List the organisms that cause community acquired acute pneumonia (7).
Which organism causes "classic" lobar pneumonia, but is also a common cause of bronchopneumonia, particularly in the elderly?
What is the clinical presentation of bacterial pneumonia (7)?
-Fever and chills
-Productive cough with rusty (bloody early in pneumococcal pneumonia), or yellow-green sputum
-Pleuritic chest pain
-Decreased breath sounds
-Rales heard with auscultation
-Dullness to percussion
Which laboratory results come with a diagnosis of bacterial pneumonia (3)?
-Elevated peripheral blood WBC count with a left shift = increased neutrophils, with usually also increased number of young neutrophils (bands)
-Sputum Gram stain positive (Note: S. pneumoniae occurs in normal pharyngeal flora)
-Blood cultures positive in 20-30% patients
Which signs of lobar pneumonia can be seen on a chest x-ray?
Lobar or segmental consolidation.
Which signs of bronchopneumonia can be seen on a chest x-ray?
Which sign of severe involvement of bacterial pneumonia can be seen on a chest x-ray?
Describe the pathogenic process of infectious pneumonia.
The symptoms of infectious pneumonia are caused by the invasion of the lungs by microorganisms and by the immune system and by the immune system's response to the infection.
Although over one hundred strains of microorganism can cause pneumonia, only a few of them are responsible for most cases. Which agents most commonly cause infectious pneumonia?
Viruses and bacteria.
Although over one hundred strains of microorganism can cause pneumonia, only a few of them are responsible for most cases. Which agents are the least common causes of infectious pneumonia?
Fungi and parasites.
What is lobar pneumonia?
Consolidation of the entire lobe.
Which organisms most commonly cause lobar pneumonia (2)?
-Streptococcus pneumoniae (95%)
Image of pneumonia in the right lower lobe with pleural effusion. Top image is a chest x-ray of normal lungs.
Image of pleural effusion. The A arrow indicates "fluid layering" in the right chest. The B arrow indicates the width of the right lung. The volume of useful lung is reduced because of the collection of fluid around the lung.
Image of chest x-ray of right upper lung lobar pneumonia.
What are the classic stages of lobar pneumonia (4)?
Describe the congestion stage of lobar pneumonia.
Heavy, boggy, red, hyperemic lungs with many bacteria but few neutrophils.
Describe the red hepatization stage of lobar pneumonia.
Massive confluent alveolar filling with RBCs, neutrophils and fibrin.
Describe the grey hepatization stage of lobar pneumonia.
Disintegration of RBCs, fibrinopurulent exudate.
Describe the resolution stage of lobar pneumonia.
Macrophages mop up debris.
Image of the red hepatization stage of lobar pneumonia.
Image of red hepatization turning into grey hepatization in lobar pneumonia.
Image of the grey hepatization stage of lobar pneumonia.
Image of the grey hepatization stage of lobar pneumonia. Diffuse change extends through the entire lobe. Alveoli are filled with fibrin and granulocytes.
Image of the grey hepatization stage of lobar pneumonia. All alveoli are filled with fibrin, edema and neutrophils. Some siderophages (hemosiderin-containing macrophages) are present.
Image of the grey hepatization stage of lobar pneumonia. Note the siderophages.
Image of lobar pneumonia with fibrinous pleuritis (anthracosis). Fibrinous pleuritis can occur in either bacterial lobar or bronchopneumonia or in viral pneumonia. Diffuse change with intra-alveolar fibrin and granulocytes. Fibrin covered pleura. Carbon in subpleural lymphatics.
What is anthracosis?
Coal workers' pneumoconiosis (CWP), colloquially referred to as black lung disease, is caused by long exposure to coal dust.
Describe the gross morphology of bronchopneumonia (2).
-Scattered patchy consolidation centered around bronchioles
-Usually bilateral, multilobar, and basilar
Describe the epidemiology of bronchopneumonia.
Affects the young, old, and terminally ill.
Which organisms most commonly cause bronchopneumonia (4)?
Describe the microscopic features of bronchopneumonia.
Acute inflammation of bronchioles and the surrounding alveoli.
Image of chest x-ray of bronchopneumonia with bilateral infiltrates.
Image of bronchopneumonia. Note the bronchoconcentric confluent yellow-white consolidated areas.
Image of acute bacterial pneumonia. Note the edema, congestion and pneumonic infiltrates.
Why are the classic stages of lobar pneumonia seldom seen in a clinical setting such that, microscopically, lobar pneumonia and bronchopneumonia look the same?
Antibiotics. It is more important to identify the causative agents.
Image of acute bacterial pneumonia. Note the hyperemia (middle), edema (right) and neutrophilic granulocytes in alveoli (left).
Image of severe acute bacterial pneumonia.
Image of acute bacterial pneumonia. Note the alveolar lumen filled with inflammatory exudate, which consists of proteinaceous debris, PMNs in varying stages of disintegration and bacteria.
Cartoon depiction of a comparison between lobar pneumonia and bronchopneumonia.
List the causative agents of community acquired atypical pneumonia (4).
-Coxiella burnetti (Q fever)
Which members of the chlamydia species cause community acquired atypical pneumonia (3)?
Which viruses are known to cause community acquired atypical pneumonia (7)?
-Respiratory syncytial virus
-Influenza A and B
Which virus is commonly linked with causing pneumonia in young children?
Respiratory syncytial virus.
CMV is especially linked with causing pneumonia in which type of patients?
Define atypical pneumonia.
Interstitial pneumonia without consolidation (if uncomplicated).
What is the epidemiology of atypical pneumonia?
It is more common in children and young adults.
Describe the chest film of someone with atypical pneumonia.
Diffuse interstitial infiltrates.
What laboratory findings come with a diagnosis of atypical pneumonia?
Elevated cold-agglutinin titers (in mycoplasma).
Image of chest x-ray displaying the interstitial pattern seen in viral pneumonia. The interstitial pattern shows fine lines radiating from the hila. There is a hazy reduction of transparency.
Image of hemorrhagic influenza pneumonia and fibrinous pleuritis. The entire lung is bluish red, heavy, and hemorrhagic. Pleural surface has fibrin strands gluing the lobes of lung together.
What are the microscopic features of viral pneumonia (4)?
-Interstitial mononuclear cell inflammatory infiltrate within the alveolar walls
-Widened, edematous septa
-Cytopathic effects (e.g. HSV) and intranuclear inclusions (CMV)
-Neutrophils, if necrosis (HSV,varicella, adenovirus)
What are the complications of viral pneumonia (3)?
-Diffuse alveolar damage
-Superimposed bacterial infection (common)
Image of acute viral pneumonia with intense vascular congestion.
Image of acute viral pneumonia with intense vascular congestion. Some alveolar lining cells have sloughed into the lumen.
Image of viral pneumonia with mild interstitial edema and swollen alveolar lining cells.
Image of viral pneumonia. Note the widened alveolar septa with mononuclear infiltrates.
Image of viral pneumonia with mild thickening of alveolar walls and bronchial wall edema.
Image of viral pneumonia with moderate mononuclear inflammatory infiltrates in the bronchial walls. No alveolar filling.
Image of cytomegalovirus pneumonia. Note the intranuclear and intracytoplasmic viral inclusions.
Summarize community acquired acute bacterial pneumonias (3).
-S. pneumoniae is the most common cause
-Distribution is usually lobar with intra-alveolar acute inflammatory cells
-Morphologic stages: congestion, red hepatization, gray hepatization, resolution
Which organism is the most common cause of pneumonia in patients with COPD (2)?
Staph aureus is linked with causing pneumonia in which conditions (2)?
-IV-drug users together with right-sided staphylococcal endocarditis
Which organism is the most common cause of pneumonia in patients with chronic alcoholism?
Which organism mostly commonly causes gram-negative bacterial pneumonia?
P. aeruginosa is linked with causing pneumonia in which type of patients (3)?
Which organism is the most common cause of pneumonia in organ transplant patients?
Summarize community acquired atypical pneumonia.
-Respiratory distress is out of proportion to the clinical and radiological signs
-Inflammation is predominantly confined to alveolar septa with clear alveoli (unless there is necrosis)
-Most common causes:
- Mycoplasma pneumoniae
- Chlamydia spp. and Coxiella burnetti (Q-fever
- Several viruses, including RSV, adenovirus (military
recruits), influenza A and B (adults), and parainfluenza
List the organisms that cause hospital acquired (nosocomial) pneumonia (3).
-Enterobacteriaceae (Klebsiella spp, Serratia marcescens, Escherichia coli)
-Staphylococcus aureus (usually MRSA = methicillin-resistant)
List the conditions or patients in which aspiration pneumonia occurs (3)
-Chemical pneumonia due to gastric acid
-Bacterial pneumonia superimposed
Which types of debilitated patients most commonly get aspiration pneumonia (2)?
-Unconscious (post-anesthesia and stroke patients)
Which types of bacteria can cause a bacterial pneumonia to be superimposed on an aspiration pneumonia (2)?
-Anaerobic oral flora
List the aerobic bacteria that can superimpose a bacterial pneumonia on an aspiration pneumonia (4).
Describe the clinical features of aspiration pneumonia (2).
-Necrosis of bronchial epithelium and lung parenchyma is common with abscess formation
-Fulminant course with high mortality
List the complications of pneumonia (3).
-Pulmonary abscesses and empyema
-Organization (repair with fibrosis)
Which organisms are linked with causing pulmonary abscesses and empyema as a result of a pneumonia infection (2)?
Describe the involvement of P. aeruginosa in the development of bacteremia with a pneumonia infection.
P. aeruginosa invades blood vessels and can cause coagulation necrosis of lung parenchyma and fulminant sepsis.
What is the definition of a lung abscess?
Disruption of normal continuity of the parenchyma by necrosis and localized collection of neutrophils.
What are the etiologies of lung abscesses (5)?
-Anaerobic bacteria almost always present
-Complication of particularly S. aureus or K. pneumoniae infection and associated with septicemia
-Bronchial obstruction due to tumor or foreign body
-Septic emboli from thrombophlebitis or infective endocarditis
What is the most common etiology of a lung abscess?
Describe the typical presentation and responsible organism of a lung abscess caused by aspiration.
-The right lower lung tends to be involved
-Caused by mixed oral flora
What is empyema and how does it differ from a lung abscess?
A collection of pus within a naturally existing anatomical cavity, such as the lung pleura. It must be differentiated from an abscess, which is a collection of pus in a newly formed cavity.
Image of aspiration pneumonia with abscess formation. The abscess cavity contains dirty gray necrotic material and the surrounding lung has areas of consolidation. This is a recent abscess with a thin wall without fibrosis. Note the pulmonary embolus adjacent to the abscess.
Image of acute aspiration pneumonia. Note the hyperemic capillaries, dense granulocytic infiltrate and aspirated muscle fiber.
Image of pneumonia with multiple abscesses. Note the emphysematous blebs.
Image of abscess forming pneumonia. More virulent bacteria and/or more severe pneumonias can be associated with destruction of lung tissue and hemorrhage. Here, alveolar walls are no longer visible because there is early abscess formation. There is also hemorrhage.
Image of lung abscess. This focal abscess containing a neutrophilic exudate as well as dark blue bacterial colonies suggests aspiration or hematogenous spread of infection to the lung. Aspirated material from the oral-pharyngeal region contains bacterial flora. Hematogenous spread of infection to lungs could occur from septicemia or from infective endocarditis involving the right side of the heart.
Image of a septic embolus. Blue masses of bacteria in a branch of the pulmonary artery. The surrounding lung is edematous.
Higher magnification image of septic embolus.
List the complications that can occur with lung abscesses (3).
List the immunocompromized hosts in which pneumonia frequently occurs (4).
-Patients on immunosuppression for transplants
-Cancer patients receiving chemotherapy or irradiation
-Sick neonates or elderly
List examples of opportunistic pulmonary pathogens (10).
Image of herpes simplex pneumonia. Note the intranuclear cowdry type A inclusions
What are cowdry inclusions?
Eosinophilic nuclear inclusions composed of nucleic acid and protein seen in cells infected with Herpes simplex virus, Varicella-zoster virus, and Cytomegalovirus. (Type A inclusions are seen with herpes).
Image of CMV pneumonia. Note the intranuclear inclusion body with halo (owl's eye).
Image of cytomegalovirus pneumonia combined with bacterial pneumonia. Severe necrotizing pneumonia; viral intranuclear inclusion bodies (arrows). Patient was HIV positive.
Image of cytomegalovirus pneumonia combined with bacterial pneumonia in HIV positive patient. Note the viral nuclear inclusion bodies and intraalveolar granulocytes (PMNs are due concomitant bacterial pneumonia).
Image of a Pneumocystis jiroveci pneumonia. Note the characteristic foamy and granular lumps in bronchoalveolar lavage fluid.
Image of Pneumocystis carinii pneumonia in an immunosuppressed patient. Note the granular, foamy PAS positive masses of organisms in alveoli with remarkably little host reaction.
Image of chronic Pneumocystis jiroveci pneumonia. Note the conglomerates of organisms.
Image of Pneumocystis jiroveci pneumonia with diffuse alveolar damage. Consolidated parenchyma with cysts.
Image of pulmonary cryptococcosis.
Image of a candida albicans infection in a patient with COPD. Note the candida-spores and pseudohyphae.
Image of an Aspergillus fumigatus infection in the bronchoalveolar lavage fluid of a heart transplant patient. Note the network of hyphae.
Image of an Aspergillus pneumonia in a patient with CLL who underwent chemotherapy. Note the necrotic area and pneumonic infiltrates.
What is Aspergillosis?
It is the name given to a wide variety of diseases caused by infection by fungi of the genus Aspergillus. The most common forms are allergic bronchopulmonary aspergillosis, pulmonary aspergilloma, and invasive aspergillosis. Most humans inhale Aspergillus spores every day. Aspergillosis develops mainly in individuals who are immunocompromised, either from disease or from immunosuppressive drugs, and is a leading cause of death in acute leukemia and hematopoietic stem cell transplantation.
Image of Aspergillosis in a CLL patient. Note the multiple necrotic lesions with a hemorrhagic rim. The patient died of fungal sepsis.
Image of Aspergillosis. Central necrosis with aspergillus hyphae. Fibrin within the alveolar spaces.
Image of Aspergillosis. Tissue necrosis with branching hyphae.
Image of invasive aspergillosis. Mycotic meningoencephalitis and fungal pneumonia in a patient with metastatic gastric carcinoma. Fungus invades blood vessels. Note the the whitish vascular invasion.
Image of invasive aspergillosis. Septate hyphi grow into pulmonary artery wall.
What are the two categories of lung disease in patients with HIV?
List the causative agents responsible for diffuse lung disease in patients with HIV (7).
List the causative agents responsible for focal lung disease in patients with HIV (9).
What are the clinical features of coccidioiodomycosis, histoplasmosis and blastomycosis (4)?
-Isolated lung involvement in immunocompetent patients with acute "flu"-like symptoms and self-limiting primary pulmonary infection with granuloma(s) in lungs and hilar lymph nodes
-Chronic granulomatous cavitary pulmonary infection in patients with massive exposure or less robust immune response
-Miliary disease without well-formed granulomas in multiple organs in immunocompromised patients
Whatis the causative agent of coccidioiodomycosis, histoplasmosis and blastomycosis?
Dimorphic fungi present in soil in endemic areas.
What is necessary for successfully fighting off coccidioiodomycosis, histoplasmosis and blastomycosis?
An intact T cell-mediated immune response is critical for containing the infection.
How is coccidioiodomycosis, histoplasmosis or blastomycosis differentiated from tuberculosis?
Identification of the organisms by PAS or silver stain is necessary for diagnosis.
Depiction of the morphology of Coccidioides immitis.
Chest x-ray of the coin lesions seen with Coccidioides immitis infection (coccidioiodomycosis or valley fever).
Image of chest x-ray of coccidioiodomycosis with a cavitary lesion in the right upper lobe.
Image of cocci granuloma. This well-formed cocci granuloma has a large Langhans giant cell in the center with two small spherules of Coccidioides immitis.
Image of cocci granuloma. A higher magnification shows the thick wall of the C. immitis spherule. The spherule contains endospores. In the United States, C. immitis is endemic to the southwest and west.
Image of coccidioidomycosis with multiple confluent granulomas.
Image of disseminated coccidioidomycosis with Coccidioides immitis spherules (sporangium).
Image of necrotic skin lesions seen in disseminated coccidioidomycosis.
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