Flashcards in L68 – Lower Respiratory Tract Infections I Deck (90):
What is the name of the inflammation in subglottis area?
Age most affected by Traceholaryngobronchitis ?
Relatively common in children: 3 months to 3 years (peak incidence at 2 years of age)
Aetiology of Traceholaryngobronchitis? (name of bacteria, viruses)
Respiratory syncytial virus (RSV)
Also Mycoplasma pneumoniae
What are some specific symptoms of Traceholaryngobronchitis?
- Laryngitis **
- Inspiratory stridor **
(= high-pitched wheezing due to disrupted airflow in upper airway)
-Dyspnea (shortness of breath) / tachypnoea
What symptom of Traceholaryngobronchitis that may not manifest?
What symptoms of Tracheolaryngobronchitis result in abnormal sound in breathing? (List the sounds)
**Rales (abnormal lung sounds: discontinuous clicking / rattling)
**Wheezing (in lower airway)
**Inspiratory stridor (= high-pitched, wheezing in Upper airway)
Describe the distinctive cough in tracheolaryngobronchitis?
Deep, brassy tone (seal’s bark)
Hoarseness (due to swollen vocal cord)
What is the method of aetiological diagnosis of tracheolaryngobronchitis?
swab >> viral antigen detection, nucleic acid amplification
optional viral culture (not routine)
What is the CXR appearance of tracheolaryngobronchitis?
tapering of tracheal width (narrows toward the top) >> steeple sign**
What are the treatment options for Tracheolaryngobronchitis?
Supportive care, e.g.:
Oxygen, ventilatory support
Nebulized bronchodilators (for wheezing in lower airway)
**no antibiotic due to usual viral aetiology**
What is the aetiology of Pertussis?
Bordetella pertussis (= Gram-negative coccobacillus)
What are the 2 steps in the pathogenesis of Pertussis?
1. Filamentous haemagglutinin (FHA) attaches to ciliated respiratory epithelium
2. Produce toxins to damage epithelium
Name some toxins made by Bordetella pertussis?
**adenylate cyclase toxin,
What is the transmission of Pertussis?
Transmitted by respiratory droplets** (>5 μm, not airborne)
What is the incubation period of pertussis?
incubation period: <1 week to >3 weeks
Pertussis affects which age groups most?
Attack rate = highest in children
Also Common cause of chronic cough in adolescents, adults
Pertussis outbreaks are community or nosocomial (hosptial)?
What are the 3 classical phases of Pertussis? CPC
Are the symptoms of pertussis the same in adults and children?
if adult have partial immunity
What are the clinical presentations of Pertussis in Catarrhal phase?
- Rhinorrhea (= runny nose)
- Conjunctival injection / bleeding
- Low grade fever
- Chronic dry cough
What are the clinical presentations of Pertussis in Paroxysmal phase?
Short expiratory bursts followed by deep inspiratory gasp (whooping cough)
Terminates with vomiting
What are the clinical presentations of Pertussis in Convalescent phase?
recovering from illness: e.g. 100 days (百日咳)
Method of definitive diagnosis of Pertussis?
Culture of nasopharyngeal aspirate / swab on Bordet-Gengou medium
What is the limitation of Culture of nasopharyngeal aspirate / swab on Bordet-Gengou medium to diagnose pertussis?
Not sensitive: usually just positive in catarrhal phase of Pertussis
Apart from Culture of nasopharyngeal aspirate, what are the 2 other methods of diagnosing pertussis?
PCR of nasopharyngeal specimens
What are the shortcomings of using serology to diagnose pertussis?
Not widely available
May not be useful in acute infections (need paired sera)
What is the treatment for pertussis?
macrolides*** inhibit 50S (e.g. erythromycin, clarithromycin, azithromycin)
What are the different MoA in macrolides given to pertussis during catarrhal and paroxysmal phase?
- Give in catarrhal phase = ↓ duration of infection
- Give in paroxysmal phase: same duration, but ↓ infectivity (less serious complications)
List come complications of Pertussis?
- CNS abnormalities (convulsion, encephalopathy)
Method of preventing pertussis? **
What are the 2 forms of vaccines for Pertussis?
Whole-cell killed vaccine: protection not lifelong
Acellular pertussis (aP) vaccine
What virulent factors of Bordetella pertussis is contained in to acellular pertussis (aP) vaccine?
filamentous haemagglutinin, pertussis toxin
Which form of vaccine for Pertussis is used in Hong Kong, why?
Acellular pertussis (aP) vaccine
Given in a quadrivalent vaccine against diphtheria, tetanus, pertussis and poliomyelitis
inflammation affecting lung parenchyma (terminal / respiratory bronchioles)
What are the routes of infection of pneumonia?
Direct inhalation of infectious particle
Aspiration of secretion from mouth and nasopharynx
(Rare) Haematogenous spread from another foci of infection in body
How does age affect the type of pathogen that causes pneumonia?
Elderly > usually bacteria (e.g. Staphylococcus aureus, Mycoplasma pneumoniae)
Children > usually virus (e.g. RSV, parainfluenza)
Name some hospital acquired pneumonia pathogens?
Escherichia coli, Pseudomonas aeruginosa, MRSA
Name some Community acquired pneumonia pathogens?
Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus,
viruses (RSV, parainfluenza)
When taking pneumonia patient history, what are some inquiries to help differentiate the type of pathogen?
Underlying illness (e.g. immunocompromised?)
Occupation and travel
Pulse-temperature deficit is a physical examination feature of pneumonia. Explain what it is.
When temperature elevations are not accompanied by a physiologic increase in the pulse
What extracts/fluids are used for culture for pneumonia?
respiratory tract specimens, blood, pleural fluid
What is the CXR result of pneumonia?
Diffuse, white lungs with lots of consolidation
How does the characteristics of sputum give clue about the pathogen causing pneumonia? Give 2 examples
‘Rusty’ sputum (dark red due to pulmonary hemorrhage) = Streptococcus pneumoniae
‘Currant-jelly’ sputum (thick, mucoid) = Klebsiella pneumoniae
From pneumonia patient: After gram satin of sputum, what cells are expected to be very abundant?
-lot of leukocytes
What mediums are used to culture pneumonia pathogens?
blood agar, chocolate agar, selective media
When is Nucleic acid amplification tests used in diagnosis of pneumonia?
upon suspicion of:
‘Atypical’ bacterial pathogens, e.g. Mycoplasma pneumoniae
What are some atypical bacterial pathogens that require PCR to diagnose pnuemonia?
Chlamydia / Chlamydophila,
Name the 3 viral investigations on respiratory specimens?
Antigen detection (e.g. direct immunofluorescent staining)
Nucleic acid amplification tests (e.g. PCR)
Which invasive method of collecting respiratory tract specimen gives better sample of lower resp. tract?
Fibreoptic Bronchoscopy + brochoalveolar lavage/ bronchial aspirate
When is Nasopharyngeal aspirate used?
mainly for respiratory viruses
What are the 4 types of respiratory tract aspirations to collect samples? PENT
Urine antigen detection test is used for which pathogens in pneumonia?
Legionella pneumophila serogroup 1
What is the empirical therapy for pneumonia?
1 beta lactam antibiotic (e.g. penicillins / cephalosporins)
± 1 macrolide (e.g. erythromycin, clarithromycin, azithromycin) or tetracycline
Difference in treatment of mild and severe pneumonia?
Mild = outpatient discharge with oral antibiotics
Severe = Inpatient with IV antibiotics, then oral
What are the classic symptoms of Acute community-acquired pneumonia?
Acute onset of fever,
pleuritic chest pain,
What bacteria causes post- epidemic / pandemic influenza secondary bacterial pneumonia?
Staphylococcus aureus (less common)
What is the most common bacteria causing Acute community-acquired pneumonia (CAP)?
Causes pneumococcal pneumonia
What are the 2 types of pneumococcal
1. Polysaccharide vaccine (23-valent)
2. Conjugate vaccine (13-valent)
List the top 3 bacteria that cause Acute community-acquired pneumonia (CAP)?
In patients with COPD, cystic fibrosis and broncheictasis, what is the bacteria most likely to cause pneumonia?
Why is Atypical pneumonia syndrome called "walking pneumonia"?
- Routine culture reveals no pathogen
- Prolonged course of illness
- Not appear very ill
Atypical pneumonia syndrome is unresponsive to which antibiotics? Thus require which antibiotics to treat?
Not responding to beta lactam antibiotics
may need macrolides, tetracyclines
Atypical pneumonia syndrome is most commonly caused by which bacteria?
(less common= Chylamydophila pneumoniae, Legionella pneumophila)
Is Serology or urine antigen detection/ Nucleic acid amplification used for atypical pneumonia syndrome?
Urine antigen detection/ Nucleic acid amplification
Serology takes too long
What age group is most affected by atypical pneumonia syndrome?
Can affect any age group
(often more severe in the elderly)
What bacteria causes Legionellosis?
Describe the O2 requirement, gram stain, spore and morphology of Legionella pneumophila.
aerobic, Gram negative, non-spore-forming bacilli
What is the reservoir of Legionella pneumophila?
natural, artificial fresh water environments
Route of transmission for Legionella pneumophila?
What are the 2 clinical diseases caused by Legionella pneumophila? PL
Describe Pontiac fever?
acute, self-limiting, flu-like illness without pneumonia
What are some symptoms of Legionnaires disease?
diarrhea, nausea, vomiting, abdominal pain
What is the best detection method of Legionella pneumophila?
Urine antigen detection
Which antibiotics are used for Legionella pneumophila?
Macrolide (erythromycin, clarithromycin, azithromycin)
Fluoroquinolone (ciprofloxacin, levofloxacin)
Which antibiotics are NOT used for Legionella pneumophila?
Beta lactam (penicillin, cephalosporin) are generally not effective
Name 3 unique risk factors of hospital acquired pneumonia?
Altered mental status
Reduced gastric acidity
Aetiology of hospital acquired pneumonia?
-Aerobic Gram negative bacteria
Give examples of Aerobic Gram negative bacteria that causes hospital acquired pneumonia?
Enterobacteriacae (ferment glucose), e.g. Escherichia coli, Klebsiella pneumoniae
Give examples of Non-fermenters bacteria that causes hospital acquired pneumonia?
Pseudomonas aeruginosa, Acinetobacter baumannii
Give examples of multi-resistant bacteria that causes hospital acquired pneumonia?
methicillin-resistant Staphylococcus aureus (MRSA)
What conditions predisposes to aspiration pneumonia?
when consciousness is altered, IMPAIRED gag and swallowing reflexes
e.g. alcoholism, cerebrovascular disorders, convulsion
What are the 3 important pathological mechanisms for aspiration pneumonia? Which of these mechanisms are acute?
1. Chemical pneumonitis
2. Bronchial obstruction with particulate matter (e.g. food)
3. Bacterial aspiration pneumonia
1 and 2 are acute, 3 takes time
What are some clinical representations of aspiration pneumonia?
fever, weight loss, productive cough, putrid sputum (rotting smell)
What is the predominant pathogen causing aspiration pneumonia?
Predominantly the oral flora:
gram negative bacilli,
Treatment for aspiration pneumonia?
broad spectrum coverage against aerobic and anaerobic organisms
What are 3 causes of empyema thoracis?
2) Intrathoracic surgery or trauma
3) Subdiaphragmatic sepsis
Pathogens that cause empyema thoracis?
Staphylococcus aureus, Streptococcus pneumoniae
After surgery/ trauma:
Aerobic Gram negative bacilli (i.e. Staphylococcus
Treatment for empyema thoracis?
Adequate drainage of abscess
Decortication (surgical removal of fibrous tissue)
Poor dental hygiene with periodental disease can predispose to what condition?