Custom Search

Pathology of Pulmonary Infection

 Dr Sampurna Roy MD       

Pulmonary Pathology Online

http://www. Pathology.htm 

Pulmonary infection occurs when normal lung or systemic defense mechanisms are impaired.   

Pneumonia and influenza account for a number deaths all over the world and are the fifth leading cause of death, exceeded only by heart disease, cancer, cerebrovascular disease and accidents.

Pneumonia can be broadly define as any infection in the lung.

Acute pneumonias may be caused by pyogenic bacteria  that induce primarily neutrophilic exudates in alveoli, bronchioles and bronchi or by a miscellaneous group of microorganisms that induce predominantly peribronchiolar and interstitial mononuclear inflammation.

The term Pneumonitis refers to the inflammatory conditions that primarily affect the interstitium.  It presents clinically as "atypical" pneumonias.

Chronic pneumonia is caused by -  Nocardia and Actinomyces species and other parasites, fungi and intracellular bacteria .

Bacterial infections occur in two frequently overlapping morphologic patterns (bronchopneumonia and lobar pneumonia ) and can be caused by a variety of gram-positive and gram-negative organisms.

Depending on bacterial virulence and host resistance, the same organism may in one case cause bronchopneumonia and in another case lobar pneumonia and sometimes intermediate involvement.

Nosocomial pneumonias develop in a number of hospitalized patients specially in critically ill patients admitted to intensive care units.

With the use of potent therapies that deliberately or incidentally produce immunosuppression there is a great risk of developing respiratory infection.

Pathogenetic organisms gain access to lung:

(i) through the airways ; (ii) through the bloodstream ; (iii) by traumatic implantation ; (iv) by a direct spread across  the diaphragm from a subphrenic source, probably through the lymphatics.

The most common route is the airways. Airway spread can result from inhalation of the organism as an aerosol on droplet nuclei.

 This is a major mechanism of spread of many viral infections and of tuberculosis.

Often development of infection begins with colonization of the upper respiratory tract by potential pathogens followed by aspiration into the lower respiratory tract.

This is a major mechanism for many of the gram-negative organisms.

Following factors interfere with normal lung defence and cause lung infection :

- Depressed bactericidal and phagocytic function of macrophage caused by starvation, alcohol ingestion, hypoxia, uremia, air pollutant, cigarette smoke and previous viral infection.

- Decrease or loss of cough reflex leading to aspiration caused by drug , anesthesis or coma.

-  Pulmonary Edema -  (a good culture medium).

- Collection of secretion.

- Poor mucociliary elevator function from smoking, infection etc.

- Cystic fibrosis, airway obstruction, chronic bronchitis .


Pulmonary Infection:

Viral Infection:

Viruses are a common cause of airway lesions but those that primarily affect the airways may also severely affect the lung parenchyma.

It is important to note that viral lung infections produce interstitial (rather than alveolar) pneumonia and diffuse alveolar damage.

Influenza (Orthomyxoviruses)

Cytomegalovirus infection



Chlamydia: Chlamydial Infection 

Rickettsia: Q Fever(Coxiella burnetii)

Mycoplasma:Mycoplasma pneumonia

Bacterial Infection:

Pneumococcal Pneumonia (Lobar Pneumonia)


Klebsiella pneumoniae

Haemophilus influenza Infection

Legionellosis (Legionnaires'Disease)

Staphylococcal Infection

Streptococcal Infection


Atypical Mycobacterial Infection

Mycobacterium Avium Intracellulare

Mycobacterium Kansasii Infection

Fungal Infection:

Histoplasmosis (Histoplasma Capsulatum)









Infections caused by other organisms

Pneumocystis Pneumonia


March 2015


Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)


submit to reddit


Dermatopathology Cases

Pancreatic Pathology Online

Gallbladder Pathology Online

Paediatric Pathology Online


Endocrine Pathology Online

Eye Pathology Online

Ear Pathology Online

Cardiac Path Online

Lung Tumour-Online


Pulmonary Pathology Online

Nutritional Pathology Online

Environmental Pathology Online

Pathology Quiz Online

GI Path Online

Soft Tissue Pathology

Case Index

Infectious  Disease Online

E-book - History of  Medicine with special reference to India


Anatomy and Histology of the Normal Lung and Airways

Examination of pulmonary and pleural biopsies

Useful  chromatic and immunostains in pulmonary pathology

Percutaneous Needle and Trucut Biopsy Specimen

Bronchial Biopsy Specimen

Transbronchial Biopsy Specimen

Transbronchial Biopsy in Lung Transplant Recipients

Examination  and Handling of Open Lung Biopsy Specimens

Lobectomy and Pneumonectomy Specimen

Histo pathological reporting of Pulmonary Parenchymal Biopsies

Histo pathological reporting of Pulmonary biopsies in cases of Idiopathic Pulmonary  Fibrosis

Closed pleural biopsy for neoplasm or inflammatory lesions 

Open pleural biopsy and pneumo nectomy or pleural  stripping

Anatomical Distribution of Pulmonary  Disease

Congenital Cystic Adenomatoid  Malformation

Broncho pulmonary Sequestration

Acute Respiratory Distress Syndrome

Neonatal Respiratory Distress Syndrome

   Disclaimer  ;  Privacy Policy  ; Advertising Policy  ;  E-mail 

           Copyright 2015
           All rights reserved