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MICBI - Clinical MICBI > L29 Bacterial and Fungal respiratory tract infections > Flashcards

L29 Bacterial and Fungal respiratory tract infections Flashcards

1
Q

Name the 3 routes of transmission of RTI.

A
  1. Aspiration: oropharyngeal secretions
  2. Inhalation: droplet nuclei, aerosols
  3. Hematogenous: e.g. staphylococcus in IVDA
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2
Q

The difference in causative agent(s) between common cold (coryza) and acute pharyngitis?

A

Common cold:
- Respiratory virus, e.g. rhinovirus, coronavirus, parainfluenza virus

Acute pharyngitis:
- Group A strep

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3
Q

The differences in symptoms (not signs!) between common cold and acute pharyngitis?

A

Common cold:
- Sore throat, cough, sneezing, rhinorrhea, nasal congestion

Acute pharyngitis:
- Sore throat, headache

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4
Q

The differences in signs between common cold and acute pharyngitis?

A

Common cold
- fever, erythematous pharynx

Acute pharyngitis
- Tendency for fever, swollen tonsils, enlarged anterior cervical nodes, scarlatiniform rash (diffuse redness over the body)

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5
Q

The difference in treatment and complications between common colda and acute pharyngitis?

A

Common cold: self-limiting; may occasionally have secondary bacterial infection

Acute pharyngitis: antibiotics; complications include rheumatic fever, acute GN

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6
Q

There are more than 200M. serotypes for the bacteria ______________, and M1 and M12 are epidemics.

A

Streptococcus pyogenes (Group A strep)

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7
Q

Diagnosis for Group A strep? (2)

A
  1. POCT (point-of-care testing, but poor sensitivity/specificity
  2. Throat swab: exudates from tonsils
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8
Q

Way of doing throat swab?

A
  • Dry swab to prevent normal flora overgrowth, but reduces bacterial survival
  • Contraindicated in suspected epiglottis (suspect if dysphagia and drooling)
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9
Q

Treatment for Group A strep?

A

Penicillin/ amoxicillin x 10 days

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10
Q

Name the 2 possible post-streptococcal diseases.

A
  1. Rheumatic fever

2. Acute glomerulonephritis

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11
Q

Which of the following about rheumatic fever as a post-streptococcal disease are correct?

A. It is MC in children from 6-15 years old
B. 2-4 weeks post-strep pharyngitis
C. It is due to circulating immune complex
D. Signs and Symptoms are related to Jones Criteria
E. Diagnosed by ASOT (Anti-streptolysin O titre) > 200 IU/ml + Anti-strep DNase B titre

A

All except C

C: pathogenesis should be anti-strep cell wall Ab cross-reacts with sarcolemma of heart and other tissues

Acute glomerulonephritis - Circulating immune complex in glomerulus;
Nephritogenic strains: M1, M12, etc. do not cause rheumatic fever

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12
Q

What are the Jones criteria?

A 
J: joint - migratory polyarthritis 
O: Heart - myocarditis/pericarditis/valvular disease 
N: nodules - subcutaneous nodules 
E: erythema marginatum 
S: Sydenham chorea
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13
Q

Onset of acute glomerulonephritis (post-streptococcal)?

A

10 days post-strep pharyngitis or pyoderma (skin infection with pus)

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14
Q

Signs and symptoms of acute glomerulonephritis and diagnosis?

A

SSx: Haematuria and AKI

- increase in ASOT (anti-streptolysin O titre), not in pyoderma

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15
Q

What is the pathological definition of pneumonia?

A

infection of the pulmonary parenchyma

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16
Q

What is the clinical definition of pneumonia?

A
  1. Consolidation (radiological or P/E) +

2. Microbiological proof (30-40%)

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17
Q 
Which of the following are clinical symptoms of pneumonia?
A. Fever
B. Chills and rigors 
C. Cough
D. SOB
E. Tachypnea
F. Pleuritis
A

All of the above

Signs: fever, tachycardia, tachypnea, signs of consolidation (dull on percussion, bronchial breathing)

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18
Q

List all the causative agents that cause
A. Typical pneumonia
B. Atypical pneumonia
(both community-acquired pneumonia- CAP)

A

A. Typical

  1. Strep. pneumoniae
  2. Haemophillus influenzae
  3. Moraxella catarrhalis

B. Atypical

  1. Mycoplasma pneumoniae
  2. Clamydophila pneumoniae
  3. Rare: Legionella pneumophila
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19
Q

What are the differences in signs and symptoms between typical and atypical pneumonia? (4)

A
  1. Fever
    Typical: High grade fever
    Atypical: Low grade fever
  2. Rigors
    Typical: common
    Atypical: uncommon
  3. Cough
    Typical: productive, purulent sputum
    Atypical: non-productive
  4. Pleuritis (pleuritic chest pain)
    Typical: common
    Atypical uncommon
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20
Q

The onset of typical and atypical pneumonia?

A

Typical: abrupt
Atypical: Gradual (3-4 days)

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21
Q

What are the CXR findings in typical and atypical pneumonia?

A

Typical: lobar consolidation
Atypical: Bilateral patchy infiltrates

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22
Q

WBC in typical and atypical pneumonia?

A

Typical: increase neutrophils
Atypical: normal

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23
Q

Culture in typical and atypical pneumonia?

A

Typical: blood agar! (also for organisms cause HAP e.g. pseudomonas);
Chocolate blood agar for H.influenzae

Atypical: Require special culture, e.g. tissue culture, mycoplasma agar

24
Q

Treatment for typical pneumonia?

A
  1. beta lactams

2. macrolides: resistant in HK

25
Q

Treatment for atypical pneumonia?

A
  1. Macrolides - increase resistance
  2. Tetracyclines: teeth discoloration
  3. Fluoroquinolones: note TB prevalence
26
Q

Streptococcus pneumoniae
A. resides in nasopharynx
B. has 98 serotypes based on polysaccharide capsule with IgA protease virulence factor
C. Enters the bloodstream via nasopharyngeal mucosal epithelium
D. Further invades the CNS
E. Causes pneumonia and bacteremia

A

All of the above

Pathogenesis: C and D

D: causes spectrum of diseases like acute otitis media, pneumonia, bacteraemia and meningitis

27
Q

Myocplasmia pneumoniae
A. Causes atypical pneumonia
B. causes malaise and headache 1-5 after chest symptoms
C. Can cause extrapulmonary manifestations like myocarditis
D. Can cause Guillain Barre syndrome
E. With cold agglutinins in blood: clumping of blood in 4 degrees Celcius

A

B is wrong, should be 1-5 days before chest symptoms

E: correct, it is one of the diagnostic tests (obsolete)

28
Q

What is the definition of Healthcare-associated pneumonia? (HAP)

A

Hospital acquired (after 48h hospital admission) or reside in a nursing home

29
Q

List causative agents that cause HAP.

3

A

Antibiotic-resistant strains

  • GN aerobes, e.g. Enterobacteriaceae (Klebsiella), P.aeruginosa
  • GN anaerobe, e.g. Bacteroides
30
Q

List causative agents that cause Aspiration pneumonia (3)

A
  1. GN aerobes e.g. Enterobacetericeae, P.aeruginosa
  2. Anaerobes from URT
    e. g. S.aureus
31
Q

What are the host factors (2) + disease factors (4) (risk factors) for HAP?

A

Host factors

  1. Old age
  2. Underlying diseases e.g. chronic lung disease, DM

Disease factors

  1. Mechanical ventilators
  2. Decreased cough reflex, e.g. opioids
  3. Broad-spectrum antibiotics
  4. Immobility and reduced consciousness
32
Q

What are the risk factors for aspiration pneumonia? (4)

A
  1. Unconscious patients
  2. Alcoholics
  3. Elderly
  4. Head injury
33
Q

List all the laboratory investigations you would order when the patient has pneumonia. (6)

A
  1. Sputum
    - early morning sputum (more concentrate)
    - AFB (acid-fast bacilli) smear (Ziehl Neelsen stain) and TB culture required in call cases of productive cough
  2. NPA (nasopharyngeal aspirate)
    - for PCR of atypical organisms + viruses (e.g. RSV, influenza)
  3. Blood culture
  4. Urine:
    - Streptococcus Ag, Legionella Ag
  5. Bronchoalveolar lavage (BAL)
    - via bronchoscopy, by injecting saline and draw, distinguish from contamination by quatitative culture (>10000 organisms/mL)
  6. Tracheal aspirate
    - in patients intubated or with tracheostomy
34
Q

To obtain best quality sputum:
A. Deep breathing exercise
B. Retaining in the mouth and spill it out to the bottle
C. Rinse mouth before collecting sputum
D. reject if 10 squamous epithelial cells (SEC) per low power field (LPF)
E. reject if without significant amount of WBC

A

All except B

Should cough directly to sputum bottle rather than retaining in the mouth

35
Q 
Management for patients with pneumonia includes Empirical treatment and treating the pneumonia of specific etiology. 
What to give if 
A. Mild to moderate pneumonia
B. Severe pneumonia
C. Structural lung disease (e.g. bronchiectasis)
D. Pseudomonas suspected
E. Aspiration pneumonia 
F. HAP
A

A: Augmentin IV/PO - amoxicillin/ clavulanate

B. Ceftriaxone (lung!) + macrolide

C. Tazocin (Piperacillin/Tazobactam)

D. Add gentamicin

E. IV cefuroxime + metronidazole (because food from intra-abdominal??)

F. Tazocin

36
Q

What to give when it is S.aureus - caused pneumonia?

A

Cloxacillin (MSSA),

Vancomycin (MRSA)

37
Q

What to give when it is Strep pneumoniae - caused pneumonia?

A

Penicillin (IC of penicillin <4 mcg/ml),

Ceftriaxone (MIC of penicillin >8 mcg/ml)

38
Q

What to give when it is Mycoplasma - caused pneumonia?

A

Macrolide

39
Q

Mycoplasma pneumoniae
A. Fried egg colonies on Eaton’s media
B. smallest free-living bacteria with no peptidoglycan wall
C. Walking pneumonia
D. CXR with patchy infiltrate
E. Positive cold agglutinin test (autoantibody to RBC)
F. Treated with macrolides

A

All of the above!

Walking on Thin Ice Sketchy!

40
Q

What vaccines can be used for strep pneumonia?

A
  1. PPSV23
    (23-valent polysaccharide vaccine)
  2. PCV13
    (13-valent protein conjugate vaccine)
41
Q

Which type of vaccine for strep pneumonia is this?

  • For adults
  • Polysaccharide from capsule
  • Weaker immune response
  • Poorer memory
A

PPSV23

23-valent polysaccharide vaccine

42
Q

Which type of vaccine for strep pneumonia is this?.

  • For children, included in childhood immunization programme (CIP)
  • Weak Ag (polysaccharide) attached to a strong Ag
  • More powerful immune response
  • Longer memory
A

PCV13

13-valent protein conjugate vaccine

43
Q

List 3 causative agents for pneumonia in the immunocompromised host
- opportunistic infections.

A

Any 3

  • Pneumocystis jiroveci (fungus)
  • Aspergillus (fungus)
  • Mycobacterium tuberculosis
  • Mycobacterium avium intracellulare
  • Nocardia species
  • Candida species (fungus)
  • Strongyloides (parasite)
44
Q

A big risk factor for chronic pulmonary sepsis is?

Examples include patients who have cystic fibrosis and is a smoker. Viral infection like measles will cause this too.

A

Impaired mucociliary clearance

impaired ciliary tree + mucus production

45
Q

What are the causative organisms for bronchiectasis? (6)

A
  1. Strep. pneumoniae
  2. S. aureus
  3. H.influenzae
  4. P.aeruginosa
  5. M. tuberculosis
  6. Aspergillus
46
Q

Risk factors for bronchiectasis? (4)

A

Congenital

  • Cystic fibrosis,
  • Kartagener’s syndrome (primary ciliary dyskinesia)

Acquired

  • post-infection (pertussis, TB)
  • airway obstruction (foreign body)
47
Q

Clinical manifestations for patients with bronchiectasis (3)

A
  1. Recurrent cough with hemoptysis
  2. Purulent sputum
    Complications
    - Cor pulmonale
48
Q

Management of patients with bronchiectasis?

A
  1. Clear secretions: physiotherapy, postural drainage
  2. Reverse airflow obstruction
  3. Medical: Abx, DNase(breaks down DNA to improve pulmonary function FEV1), gene therapy
  4. Surgical: arterial embolization, resection
49
Q

Acute exacerbation of COPD (chronic bronchitis) is usually due to total burden of inhaled particles - smoking, occupational dust and air pollution.
What are the commonest causative organisms? (4)

A
  1. H. influenzae (MC)
  2. Strep. pneumoniae
  3. S.aureus
  4. P.aeruginosa
50
Q

Clinical manifestations for acute exacerbation of COPD? (3)

A
  1. Increase SOB
  2. Sputum - increased production, more mucopurulent
  3. Coughing
51
Q

What maintenance therapy are given to patients with acute exacerbation of COPD? (3)

A
  • Bronchodilators
  • Antibiotics for 7-10days
  • Physiotherapy
52
Q

What is empyema?

A

Accumulation of pus in pleural space

53
Q

Causes for empyema?

State the cause and the organism

A
  1. Pneumonia due to H.influenzae (MC), Strep. pneumoniae, S.aureus
  2. Thoracic surgery, trauma: S.aureus, GN bacilli
  3. Esophageal perforation
  4. Subdiaphragmatic infection: anaerobes
54
Q

Clinical manifestations of patients with emypema?

A
  • Non-specific constitutional Sx, e.g. weight loss, fever, night sweats
  • Pleural effusion
55
Q

How to diagnosis empyema? (1)

Tx?

A

Pleural aspirate

Tx
- Pus drainage (thoracentesis)
- Abx (anaerobic coverage) x2-4/52
[prolonged in long-standing cases and Actinomyces (anaerobe, v. invasive)]

56
Q

Aspiration, Periodontal disease, Underlying lung disease like bronchiectasis and Immunosuppression are all risk factors to lung absecess.
What are the causative organisms?

A
  1. Oropharyngeal flora
  2. Nosocomial e.g. S.aureus
  3. Anaerobes e.g. bacteroides
57
Q 
Lung abscess can cause constitutional symptoms liek malaise, LG fever and weight loss, anemia.
Productive cough too.
Complications include
- Empyema
- bronchopleural fistula
- brain abscess

Dx and Tx?

A

Dx: BAL, empyema fluid, blood

Tx:

  • Abx: anaerobic coverage, 2-4/52
  • Pus drainage

MICBI - Clinical MICBI (19 decks)

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