Pulmonary Infections Flashcards by Kayla Schenheit

What is pneumonia?

Infection of the lung parenchyma

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When does pneumonia occur?

When normal defense are impaired.

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What are examples of normal defenses being impaired in pneumonia?

Impaired cough reflex (can’t remove organisms, chemicals)
Damage to mucociliary escalator (beats upward and allows up to clear out things trapped in the mucous)
Mucus plugging (blocks airway and increases infection risk)

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How can viral pneumonia impair normal defenses in the lung?

Viral pneumonia damages respiratory epithelial cells. This inactivates the elevator and increases the risk of bacterial infection in addition to the viral pneumonia.

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What are the clinical features of pneumonia?

Fever and chills
Productive cough with sputum
Tachypnea
Pleuritic chest pain
Decreased breath sounds
Dullness to percussion
Elevated WBC count

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What type of sputum might you see in pneumonia?

yellow-green (pus)

- rusty (bloody) sputum

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How is a pneumonia diagnosis made?

CXR
Sputum gram stain
Sputum culture
Blood culture

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What causes pleuritic chest pain?

From stretching pleural.
-Bradykinin & PGE2 sensitizes nerves in the area
(these are two key mediators of pain)

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What are the three classic pneumonia presentations seen on chest x-ray?

Lobar pneumonia
Bronchopneumonia
Interstitial (atypical) pneumonia

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What is the interstitium of the lungs?

Connective tissue of the alveolar air sac.

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What causes fever and chills in pneumonia?

Bacteria spilling into the blood

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What type of pneumonia is usually bacterial?

Lobar pneumonia

- Bronchopneumonia

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What type of pneumonia is usually viral?

-Interstitial (atypical) pneumonia

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What is Lobar pneumonia?

Characterized by consolidation of an entire lobe of the lung

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What are the top causes of Lobar Pneumonia? What is the percentage associated with those causes?

Usually bacterial

Most common cause (95%) Streptococcus pneumoniae
Klebsiella pneumoniae

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What are the four classic gross phases of Lobar Pneumonia?

Congestion
Red hepatization
Gray hepatization
Resolution

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What causes congestion?

Due to congested vessels and edema.

dilated vessels leads to an increased amount of blood

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What causes red hepatization?

Due to exudate, neutrophils and hemorrhage filling the alveolar air spaces, giving the normally spongy lung a solid consistency

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What causes gray hepatization?

Due to degradation of red cells within exudate.

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What causes resolution?

Healing of the lung is done through regenerating tissue normally present at that site.

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What is hepatization?

“Liver like change”

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What is a Type II pneumocyte?

Stem cell of the lung that helps regenerate the lining of the air sacs.

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What age group is lobar pneumonia common in?

Middle aged adults and elderly

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What is secondary pneumonia?

Bacterial pneumonia superimposed on a viral upper respiratory tract infection.

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What is the most common cause of community-acquired lobar pneumonia and secondary lobar pneumonia?

Streptococcus pneumoniae (95%)

What causes Klebsiella pneumoniae lobar pneumonia?

Enteric flora that has been aspirated

What populations does Klebsiella pneumoniae lobar pneumonia affect?

Malnourished and debilitated individuals, especially in nursing homes, alcoholics and diabetics

What type of sputum is characteristic of Klebsiella pneumoniae?

Red currant jelly

What causes the currant jelly sputum seen in Klebsiella pneumoniae lobar pneumonia?

Thick mucoid capsule results in gelatinous sputum.

What is Klebsiella pneumoniae lobar pneumonia often complicated by?

Abscess

What characterizes Bronchopneumonia?

Scattered patchy consolidation centered around bronchioles; often multifocal and bilateral

What types of organisms cause Bronchopneumonia?

USUALLY BACTERIAL | Variety of bacterial organisms

What is the most common cause of Secondary Bronhopneumonia?

Staphyloccus aureus

What is Staph. aureus Bronchopneumonia often complicated by?

Abscess or Empyema

What is another common cause of secondary bronchopneumonia and also pneumonia superimposed on COPD? What does this lead to?

Haemophilus influenzae. | When this bug is superimposed on COPD, it leads to an exacerbation of COPD.

What population does Pseudomonas aeruginosa commonly cause Bronchopneumonia in?

Cystic fibrosis patients

What two types of Bronchopneumonia can Moraxella catarrhalis cause?

1. CAP (community-acquired pneumonia) | 2. Pneumonia superimposed on COPD

What three types of Bronchopneumonia can Legionella pneumophila cause?

1. CAP (community-aquired pneumonia) 2. Pneumonia superimposed on COPD 3. Pneumonia in immunocompromised states

How is Legionella pneumophila transmitted?

Transmitted from water source

What type of organism is Legionella pneumophila and how can it be visualized?

- Intracellular organism! | - Silver stain

What is Interstitial Pneumonia? What is it also referred to as?

Atypical pneumonia | -Characterized by diffuse interstitial infiltrates

What do you see in CXR of Interstitial (Atypical) Pneumonia?

Increased lung markings

What types of organisms are the most common cause of Interstitial (Atypical) Pneumonia?

VIRUSES!!

What does Interstitial (Atypical) Pneumonia typically present with?

Relatively mild upper respiratory symptoms (minimal sputum, cough and low fever); atypical presentation

What types of organisms can cause Interstitial (Atypical) Pneumonia?

Viruses or Bacteria

What do you see microscopically in Interstitial (Atypical) Pneumonia?

- Predominantly empty air sacs | - Many inflammatory cells in the wall of the interstitium

What is the most common cause of Interstitial (Atypical) Pneumonia?

Mycoplasma pneumoniae

What groups does Mycoplasma pneumoniae usually effect?

Young adults (classically military recruits and college students living in the dormitory)

What are complications of Mycoplasma pneumoniae?

- Autoimmune hemolytic anemia | - Erythema multiforme

What causes cold hemolytic anemia in Mycoplasma pneumoniae Interstitial pneumonia?

IgM against I antigen on RBCs

Why isn't Mycoplasma pneumoniae visible on gram stain?

Due to lack of cell wall.

What is the second most common cause of Atypical Pneumonia in young adults?

Chlamydia pneumoniae

What is the most common cause of atypical pneumonia in infants?

Respiratory syncytial virus (RSV)

What is the most common cause of atypical pneumonia with post transplant immunosuppressive therapy?

Cytomegalovirus (CMV)

What is the cause of Atypical pneumonia in elderly, immunocompromised, and those with preexisting lung disease?

Influenza virus

What atypical pneumonia cause leads to increased risk for superimposed S. aureus or H. influenzae bacterial pneumonia?

Influenza virus

What atypical pneumonia cause is seen in farmers and veterinarians?

Coxiella burnetii

What symptom is associated with Coxiella burnetii Atypical Pneumonia?

High fever (Q fever)

How does Coxiella burnetii spread?

Coxiella spores are deposited on cattle by ticks or are present in cattle placentas

What type of organism is Coxiella burnetii?

Rickettsial organism

Why is Coxiella burnetii distinct from most other rickettsial organisms (three reasons)?

(1) It causes pneumonia (2) It does not require arthropod vector for transmission (survives as highly heat-resistant endospores) (3) It does not produce a skin rash

What patients is Aspiration Pneumonia seen in?

Patients at risk for aspiration (e.g., alcoholics, comatose patients)

What is Aspiration Pneumonia often due to?

Anaerobic bacteria in the oropharynx (e.g., Bacteroides, Fusobacterium and Peptococcus)

What does Aspriation Pneumonia classically result in?

Right lower lobe abscess

Why does Aspiration Pneumonia often result in right lower lobe abscess?

Anatomically, the right main stem bronchus branches at a less acute angle than the left (this makes it easier for aspirate to go down the right rather than left bronchi!)

What causes Tuberculosis (TB)?

Due to inhalation of aerosolized Mycobacterium tuberculosis.

What is Primary TB?

It arises with initial TB exposure

What does Primary TB result in?

-Focal, caseating necrosis in the lower lobe of the lung and hilar lymph nodes

What happens to the focal, caseating necrosis in primary TB?

It undergoes fibrosis and calcification, forming a Ghon complex.

What is a Ghon complex?

Fibrosed, calcified nodule in the subpleural lung and lymph nodes

What symptoms are associated with Primary TB?

Generally asymptomatic

What test result does Primary TB lead to?

A positive PPD.

What is Secondary TB?

It arises with reactivation of Mycobacterium tuberculosis (reactivated Ghon complex)

What commonly causes reactivation of TB?

- Commonly due to AIDS | - May also be seen with aging

Where does secondary TB most often occur?

At the apex of the lung

Why does secondary TB often occur at the apex of the lung?

There is relatively poor lymphatic drainage and high oxygen tension.

What is formed during secondary TB?

Cavitary foci of caseous necrosis

What does the caseous necrosis lead to in secondary TB?

It may lead to: (1) Miliary pulmonary TB OR (2) Tuberculous bronchopneumonia

What is miliary pulmonary TB?

Tiny regions of TB scattered across the lung!

What are the clinical features of Secondary TB?

- Fevers - Night sweats - Cough with hemoptysis - Weight loss

What does biopsy of Secondary TB reveal?

Caseating granulomas

What does AFB stain of Secondary TB reveal?

Acid-fast bacilli

What should you know about systemic spread of secondary TB?

Systemic spread often occurs and can involve any tissue!

What are common sites of secondary TB spread?

1. Meninges (meningitis) 2. Cervical lymph nodes 3. Kidneys (sterile pyuria) 4. Lumbar vertebrae (Pott disease)

What do you see in sterile pyuria?

WBC in the urine but no bacteria!

What is meningitis cause by secondary TB?

It is meningitis with granulomas at the base of the brain!