Pathology of Pulmonary Infections Flashcards
What is pneumonia?
Infection involving the distal airspaces usually with inflammatory exudation where fluid filled spaces lead to consolidation
Which types of organisms can cause pneumonia? (3)
Viruses
Bacteria
Fungi
Which viruses can cause pneumonia?
Influenza Parainfluenza measles Varicella-zoster Respiratory syncytial virus (RSV)
Which bacteria can cause pneumonia?
Chlamydia
Mycoplasma
Fungal pneumonia only really occur in _______ patients
Immunocompromised
What is lobar pneumonia?
Confluent consolidation involving a complete lung lobe
What causes lobar pneumonia (organisms)
Strep pneumoniae or other organisms(Klebsiella/Legionella)
What is the clinical setting of lobar pneumonia?
Usually community-acquired
Classically in otherwise healthy young adults
What distinguishes between lobar and bronchopneumonia?
Morphology
Pathology of lobar pneumonia involves a classical ______ __________ response
acute immune
What are the possible complications of lobar pneumonia?
Fibrous scarring
Abscess
Bronchiectasis
Empyema
What is bronchopneumonia?
Patches of pus/infection thought the lung
Mostly associated with airways
What are the causes of bronchopneumonia?
COPD
Cardiac failure
Complicate not viral infection
Aspiration
Which organisms are found in bronchopneumonia?
Strep. pneumoniae Haemophilus influenza Staphylococcus Anaerobes Coliforms
Aspiration-caused bronchopneumonia is associated with which organisms?
Staph
Anaerobes
Conforms
What are the possible complications of bronchopneumonia?
Organisation (scarring)
(lung) Abscess
Bronchiectasis
Empyema
What is bronchiectasis?
Chronic infection of the bronchi and bronchioles leading to permanent dilation of these airways
What are the main organisms associated with bronchiectasis?
Haemophilia influenza
Strep pneumonia
Staph aureus
Pseudomonas aeruginosa
What are the congenital causes of Bronchiectasis?
Cystic fibrosis
Young’s syndrome
Primary ciliary dyskinesia
Kartagener’s syndrome
What are the post-infection causes of bronchiectasis?
Measles Pertussis Bronchiolitis Pneumonia HIV TB
What are other other (non-congenital/non-post-infection) causes of bronchiectasis?
Bronchial obstruction Allergic broncho-pulmonary aspergillosis Hypo-gammaglobulinaemia Rheumatoid arthritis Ulcerative colitis Idiopathic
Tuberculosis is …
a mycobacterial infection found in many body sites
What characterises the pathology of TB?
Delayed (type IV) hypersensitivity leading to granulomas with necrosis
Which organisms are the main pathogens in TB?
M. tuberculosis
M. bovis
What gives TB-causing-organisms their pathogenicity?
Ability to avoid phagocytosis and simulate a host-T-cell response
What constitutes immunity in TB?
T-cell response to organism enhances macrophage ability to kill mycobacteria
What constitutes hypersensitivity in TB?
T-cell response causes granulomatous inflammation, tissue necrosis and scarring
What is meant by primary tuberculosis?
1st exposure and up to 5 years after
What occurs when first exposed to TB?
Inhaled organism > phagocytosed > carried to hilar lymph nodes > immune activation > granulomatous response in nodes + lungs
Usually causes killing of organism / sometimes overwhelming and spreads
What is meant by secondary tuberculosis?
Reinfection or reactivation of disease in person with some immunity
In secondary tuberculosis disease tends to be _______ (often in ___ of lungs) but can progress to spread by ______ or _______
localised
apices
airways
bloodstreams
Which tissue changes occur in primary TB?
Small focus (Ghan focus) in periphery / mid zone of lung
What tissue changes occur in secondary TB?
Fibrosing and caveating apical vision
What causes reactivation of TB?
decreased T-cell function
What causes decreased T-cell function?
Age
Coincident disease (HIV)
Immunosuppressants (steroids/chemotherapy)
When does reinfection with TB occur?
At higher dose or with more virulent organism
What are opportunistic pathogens?
Pathogens that aren’t normally disease causing but cause disease in immunocompromised patients
What are examples of opportunistic pathogens that cause infection in the immunocompromised?
Viral (Cytomegalovirus - CMV)
Bacteria (Mycobacterium avid intracellulare)
Fungi (aspergillus / Candida / Pneumocystis)
Protozoa (Cryptosponridia / toxoplasma)
How is TB diagnosed?
high index of suspicion
MDT
Bronchoalveolar lavage
Biopsy with stains
