Pathology of Respiratory Tract Infections Flashcards
What are different kinds of microorganisms in terms of pathogenecity?
Primary
Facultative
Opportunistic
What are primary microorganisms?
Can establish an infection in almost anyone
What are facultative microorganisms?
Requires defences to be reduced a little bit to cause disease
What are opportunistic microorganisms?
Not very infectious, do not have pathogenic properties to invade human tissue, but if defences are dropped then they can cause a clinically evident infection
What does the ability to resist infection depend on?
State of the host defence mechanism
Age of patient
What are some upper respiratory tract infections?
Coryza (common cold)
Sore throat syndrome
Acute laryngotracheobronchitis (coup)
Laryngitis
Sinusitis
Acute epiglottitis
What is the common cold also known as?
Coryza
What is coup also known as?
Laryngotracheobronchitis
What is acute epiglottis commonly caused by?
Group A beta haemolytic streptococci
Haemophilus influenza
Who seems to be most prone to acute epiglottitis?
Young children
What are some examples of lower respiratory tract infections?
Bronchitis
Bronchiolotis
Pneumonia (acute inflammatory process in the alveoli)
What is pneumonia?
Acute inflammatory process in the alveoli
What are some respiratory tract defence mechanisms?
Macrophage-mucociliary escalator system
General immune system
Respiratory secretions
Upper respiratory tract as a filter
What is the macrophage-mucociliary escalator system composed of?
Alveolar macrophages
Mucociliary escalator
Cough reflex
How does the upper respiratory tract help to prevent the lower respiratory tract from becoming infected?
Warms and humidifies air, supplying a large surface area where material in the air may be deposited so it does not reach the lower respiratory tract
How are particles cleared from the lungs?
Macrophage-mucociliary escalator:
1) Macrophages clear particles by phagocytosis
2) Leave via the muco-ciliary escalator or through lymph
What is pneumonia classified by?
Anatomical (understand radiology)
Aetiological (how acquired, such as from a hospital or community)
Microbiology (tells us how to treat the patient)
What are some different aetiological classifications of pneumonia?
Community acquired
Hospital acquired (nosocomial)
Pneumonia in the immunocompromised
Atypical pneumonia (caused by unusual organism)
Aspiration pneumonia
Recurrent pneumonia
What is a hospital acquired infection also known as?
Nosocomial infection
What are infections from hospital more likely to be?
Resistant to antibiotics
What are some different patterns of pneumonia?
Bronchopneumonia
Segmental
Lobar
Hypostatic
Aspiration
Obstructive, retention, endogenous lipid
What is hypostatic pneumonia?
Patient has some other pathological process that lead to the accumulation of fluid in the lung, such as cardiac failure with chronic edema
What occurs in bronchopneumonia?
Acute inflammation
Pus from polymorphs replaces air
Accumulation of neutrophils in alveolar space
What is the infected site in segmental and lobar pneumonia normally like?
Unilateral in a single site or area of the lung which is infected
How does segmental and lobar pneumonia differ from bronchopneuonia?
Segmental and lobar are at a single site whereas broncho is multilocal
What is bronchopneumonia characerised by?
Spots of infection stay around alveoli
Rare for infection to reach the pleura
Basal parts of the lungs infected
What is lobar pneumonia characterised by?
Large amount of lung infected by the same inflammatory process
Could be an entire lobe
Meaning the whole part is airless due to being filled with pus
What kind of pneumonia could lead to a pleural infection?
Lobar, pleural infections are rare with bronchopneumonia
What are possible outcomes of pneumonia?
Most resolve
Pleurisy, pleural effusion and emphysema
Organisation
Lung abscess
Bronchiectasis
What are examples of pneumonia leading to organisation?
Mass lesion
Cryptogenic organising pneumonia (COP)
Constructive bronchiolotis
What could pneumonia lead to instead of resolution?
Fibrosis
Abscess (infected area dies which creates a hole in the lung)
What can the outcome of pneumonia mimic?
Can result in a lump which mimics cancer, only to realise it is not cancer once it has been removed