LRTI I Flashcards
Bronchitis
Characterised by temporary (self limited) inflammation of the large and mid sized bronchial tubes
Epidemiology of bronchitis
Seasonal variation; peak incidence in winter and where influenza (outbreak?) is present in the community.
Risk factors include:
(1) Age (ie children <5 years and the elderly)
(2) Underlying disease (ie chronic obstructive pulmonary disease (COPD), asthma)
(3) Exposure to second-hand smoke
Microbiology of bronchitis
Viral
- Influenza virus
- Rhinovirus
- Adenovirus
- Respiratory synctial virus (RSV)
- Human metapneumovirus
Bacteria (approximately 10% of cases)
- Mycoplasma pneumoniae
- Chlamydophila pnumoniae
- Bordetella pertussis (rare cases)
Pathophysiology of bronchitis
A virus(es) replicating in the epithelial cells of the upper respirtaory tract can spread to the lower airways resulting in:
- Inflammation of the bronchial/bronchiolar epithelia (ie. infiltration of mononuclear cells)
- Necrotic epithelia sloughed off into the lumina of the airways, togetehr with inflammation and increased mucous production and oedema, can cause obstruction characterised by ‘wheezing’.
Bronchitis clinical manifestations
Symptoms usually begin with common cold syndrome
- nasal congestion, rhinitis, sore throat, and general malaise
- low grade fever (37.5-38)
- Cough (dry at first/ becomes productive [white; green; yellow sputum])
- Wheezing *
Symptoms and signs usually resolve over 7-10 days for otherwise healthy person
Diagnosis of bronchitis
Made on clinical presentation, suspected in any person with acute respiratory illness where cough is the dominant symptom.
Differential diagnosis of bronchitis
Pertussis (whooping cough)
Pneumonia (i.e. chest x-ray with signs of infiltrates/consolidation)
Chronic obstructive pulmonary disease (COPD); asthma.
Treatment of bronchitis
Supportive therapy: adequate hydration, cough suppressants, decongestants, antihistamines.
Bronchiolitis
Describes inflammation of the smaller air passages, bronchioles, of the lung.
Bronchiolitis epidemiology
Peak incidence is during winter to early spring; usually correlated with the prevalence of RSV in the community.
Most common during the first years of life:
- each uear 1-3% of infants <6 months of age
- more common in boys
- children with chronic underlying conditions (i.e. cardiopulmonary function decline)
Bronchiolitis risk factors
Young maternal age Lower cord blood antibody titres to RSV Lower socioeconomic status Crowded living conditions Bottle feeding Tobacco/smoke exposure
Bronchiolitis microbiology
Viruses (order of prevalence)
- RSV
- Rhinovirus
- Influenza
- Parainfluenza virus (1-3)
- Adenovirus
- Bocavirus
- Non-SARS coronaviruses
Bronchiolitis clinical manifestations
Prodrome (range 2-7 days) of signs of upper respiratory tract infection:
- Coryza
- Cough
- Fever (usually mild)
Followed by:
- Wheezing
- Dysponea
- Dehydrations (due to coughing spasm associated vomiting/ poor oral intake)
- Recovery usually over a period of 1-2 weeks.
Bronchiolitis diagnosis
Based on child’s history and physical examination
Usually suspected in children <2 years of age with:
- cough
- wheezing
- increased respiratory effort
Bronchiolitis differential diagnosis
Broad and usually includes:
- obstruction of an airways by foreign body.
- retropharyngeal abscess
- cystic fibrosis
- congestive heart failure
Bronchiolitis treatment
Supportive care for outpatient and inpatient
Maintain comfort and hydration
Treat for fever where necessary.
Factors that increase the risk of community-acquired pneumonia
Age over 50 years Alcoholism Asthma COPD Dementia HF Diabetes Immunosuppression Indigenous background Institutionalisation Seizure disorders Smoking Stroke
Factors that might perturb airway defence systems predisposing to pneumonia
(1) Cigarette smoke (disrupts mucociliary function and macrophage activity)
(2) Alteration in consciousness (stroke, seizures, anaesthesia, alcohol abuse, normal sleep)
(3) Iatrogenic manipulations (endotracheal tubes, nasogastric tubes, other respirtaory therapy machinery)
(4) Congenital defects in ciliary activity (immotile cilia syndrome)
(5) Underlying respiratory tract disorders (chronic obstructive pulmonary disease [COPD], bronchiecstasis, cystic fibrosis)
Common bacterial causes of pneumonia
Streptococcus pneumoniae* Staphylococcus aureus*
Haemophilus influenzae*
Anaerobes (Bacteriodes species; Fusobacterium species; Prevotella species) Escherichia coli
Klebsiella pneumoniae*
Enterobacter species
Serratia species
Pseudomonas aeruginosa*
Intracellular/atypical bacterial causes of pneumonia
Legionella pneumophila* Mycoplasma pneumoniae* Chlamydophila psittaci* Chlamydophila pneumoniae* Chlamydia trachomatis Mycobacterium tuberculosis Coxiella burnetii
Common viral causes of pneumonia in children
Respiratory syncytial virus (RSV) Parainfluenza virus types 1-3 Influenza A virus
Common viral causes of pneumonia in adults
Influenza A virus
Influenza B virus
RSV
Human metapneumovirus Adenovirus types 4 and 7 (ie., military staff)
Fungal causes of pneumonia
Histoplasma capsulatum Coccidiodes immitis Rhizopus species Absidia species
Mucor species Aspergillus species Candida species
What is important information to obtain when taking a history of a patient with suspected pneumonia?
(1) Clinical setting - community acquired/hospital acquired
(2) Predisposing/underlying disorders in patients
(3) Possible exposure to specific pathogens (travel to tropical areas, occupation, pets)
