Pneumonia

Pneumonia is infection of pulmonary parenchyma.

It is a lower respiratory tract infection which involves mainly lungs.

Person of any age can get this infection but infants (<2 years) and elderly people are at higher risk.This is probably due to their weakened immune system.

What are the causes of Pneumonia:-

(1) Bacterial infection.

(2)Loss of suppression of the cough reflex.

     -coma 

     - anaesthesia

     -Neuromuscular disorders

(3) Injury to mucociliary apparatus

(clearing mechanisms are impaired)

    -cigaratte smoke

    - inhalation of hot or corrosive gases

    - viral disease

    - Immotile cilia syndrome

(4) Pulmonary congestion and edema

Clinical features:-

 -high grade fever

 - productive cough

 - pleuritis

Chest X- ray finding:-

  -signs of consolidation

Types of pneumonia:-

1. Typical/Air space pneumonia:-

   - accumulation of intra-alveolar exudate following a bacterial infection.    

   

Typical pneumonia can be further divided into 2 types:-

•    Lobar pneumonia
•   Broncho pneumonia

Lobar pneumonia

•  extensive involvement of whole lobe of lung
• more common in adults
• can occur in healthy persons
• Causative bacteria are:- • pneumococcus

                                               • Klebsiella pneumonia

                                               •Staphylococcus

                                               •Streptococcus

   - infection spread through bronchial lumen

    - good prognosis

NEET -2020

Bronchopneumonia :-

• Patchy consolidation of mostly basal lobe of the lung.
• More common in infants and old age
• Occur if presence of pre-existing disease
• Causative bacteria of bronchopneumonia are:-       staphylococcus                                                       streptococcus                                                           H.influenzae
• Infection spread through walls of the bronchus
• Poor prognosis

Staging of lobar pneumonia:-

1. Congestion

    - it persist for initial 2 days

    - characterised by presence of fluid in alveoli which is further complicated by bacterial infection and presence of neutrophils.

2. Stage of red hepatization:-

   -it persist for 3-4 days after congestion

   -there is leakage of RBC clot in alveolar fluid along with fibrin deposition in small amount

  - lung appear firm,red like liver.

 3. Stage of grey hepatization:-

  - it persist for 5-8 days after 2nd stage

  -in this stage the RBC trapped inside alveolar fluid get trapped along with extensive fibrin deposition

 4. Resolution:-

    In this stage neutrophils and macrophages phagocytose the cellular debris

(2) Atypical pneumonia:-. 

    - no bacterial etiology

    - characterised by interstitial tissue inflammation followed by mononuclear infiltration (lymphocyte)

Clinical features:- 

-fever

- non productive cough

- malaise

Chest X-ray finding:-

  -No sign of consolidation

   -Interstitial tissue markings

Atypical pneumonia caused by:-

 -Mycoplasma

 -chlamydia

 -Coxiella Burnetti

 -influenza virus

 -respiratory syncytial virus