Lecture 14- Lower respiratory tract infections and pneumonia Flashcards
Lower respiratory tract infections (LRTI) are a leading cause of death in the
elderly
Course of typical infection
- Alveolar macrophages fails to stop pathogen
- Cytokines to recruit more macrophages
- Inflammation= increased permeability
- More WBC/proteins
- Neutrophils
- Lymphocytes
- Antibodies to aid macrophage
course of typical infection outside the lungs
- Inflammatory mediators (cytokines) into systemic circulation
- Physiological- activates bone marrow/more CO and raised body temp
- Dysregulation/ pathological inflammation– signs of tissue injury/ organ injury (multi-organ failure- low BP due to vasodilation of blood vessels in response to inflammation e.g. liver and kidney failure due to low BP
Inflammation=
increases blood supply and increases WBC to the site of infection via the release of cytokines
- Damages lung tissue
common microbiota of the resp tract
- Viridians streptococci
- Neisseria sp
- Anaerobes candida sp
Less common microbiota of respiratory tract
- Streptococcus’s pneumoniae
- Streptococcus pyrogens
- Haemophilus influenzae
Others
- Pseudomonas
- E.coli
Upper resp tract=
nasal cavity to the larynx
lower resp tract
trachea –> lungs
lungs are not
sterile
- normal alveolar microbiota
- aspiration
- blood stream spread
- direct spread
Defences of resp tract
- Muco-ciliary clearance mechanisms nasal hairs, ciliated columnar epithelium of the resp tract
- Cough and sneezing
- Respiratory mucosal immune system
- Lymphoid follicles of the pharynx and tonsils, alveolar macrophages, secretary IgA and IgG
- Alveolar microbiota
what causes dyrefulation of inflammation
- the pathogens virulence factors
- host factors
- drugs
pathogen virulence factors
What causes dysregulation of inflammation: host factors
- Over 75
- Lifestyle
- Smoking (abnormal ciliary function)
- Alcohol/drugs
- Chronic lung disease e.g. bronchiectasis, CF
- Aspiration
- Change in level of consciousness
- Dysphagia
- Wearing dentures whilese sleeping
- Immunocompromised
- DM
- HIV
- Metabolic
- Malnutrition
- Hypoxaemia
- Acidosis
- Uraemia
- Co-infection with viruses (abnormal ciliary function)
What causes dysregulation of inflammation: drugs
- Antacids
- Antipsychotics
- ACE inhibitors
- Glucocorticoids
- Antacids
- PPI- increases risk for pneumonia
- H2 antagonist- myelosuppression (rare, long term)
- ACE inhibitors-
associated reduced risk but only seen in observational studies with reporting bias
- Glucocorticoids-
use of inhaled corticosterois
types of URTI
- Rhinitis
- Pharyngitis
- Epiglottis
- Laryngitis
- Tracheitis
- Sinusitis
- Otitis media
URTI are most commonly caused by
viruses
- Rhinovirus
- Coronavirus
- Influenza/parainfluenza
- Respiratory syncytial virus (RSV)
Bacterial superinfection (after viral infection)
*
- Common with
- Sinusitis and otitis media–> can lead to mastoiditis, meningitis, brain abscess
Lower respiratory tract infections
- bronchitis
- pneumonia
- bronchiolitis
- empyema
- bronchiectasis
- lung abscess
- Bronchitis =
infection of the bronchi
- Pneumonia=
infection of the lung parenchyma
LRTI definittions (inflammation of the lungalveoli)
- community acquired pneumonia (CAP)
- hospital acquired pneumonia (HAP)
- venitalted acquired pneumonia (VAP)
community acquired pneumonia (CAP)
outside healthcare setting
HAP
48 hours post admission
VAP (ventilator)
48h post intubation