MI: Respiratory Tract Infections Flashcards

1
Q

List some ways in which the body can be compromised, thereby increasing the risk of respiratory tract infection.

A
  • Poor swallow
  • Abnormal ciliary function (e.g. smoking)
  • Abnormal mucus (e.g. CF)
  • Dilated airways (e.g. bronchiectasis)
  • Defect in host immunity
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2
Q

What type of bacterium is Streptococcus pneumoniae?

A
  • Gram-positive cocci in chains
  • Alpha-haemolytic and optochin-sensitive
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3
Q

Why is no microbiological identification of the pathogen made in the most cases of CAP?

A

Difficult to obtain a good sputum sample and early treatment is usually initiated with empirical antibiotics

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4
Q

List the main organisms that cause CAP.

A
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Staphylococcus aureus
  • Klebsiella pneumoniae
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5
Q

List the most prevalent pathogens causing CAP in the following age groups:

  • 0-1 months
  • 1-6 months
  • 6 months - 5 years
  • 16 - 30 years
A

0 - 1 months:

  • Escherichia coli
  • Group B Streptococcus
  • Listeria monocytogenes

1-6 months:

  • Chlamydia trachomatis
  • Staphylococcus auerus
  • RSV

6 months - 5 years:

  • Mycoplasma pnaeumoniae
  • Influenza

16-30 years:

  • Mycoplasma pneumoniae
  • Streptococcus pneumoniae
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6
Q

List the causes of CAP that fall into the following two categories:

  • Typical
  • Atypical
A

Typical:

  • Streptococcus pnaeumoniae
  • Haemophilus influenzae

Atypical:

  • Legionella
  • Mycoplasma
  • Coxiella burnetii
  • Chlamydia psittaci
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7
Q

What is the CURB-65 score? How is it interpreted?

A
  • Confusion
  • Urea > 7 mmol/L
  • Respiratory rate > 30/min
  • BP < 90 systolic, < 60 diastolic
  • Score of 2 = consider hospital admission
  • Score of more than 2 = severe pneumonia that may need ITU admission
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8
Q

Outline the presentation of bronchitis.

A
  • Cough
  • Fever
  • Increased sputum production
  • Increased SOB
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9
Q

Which organisms cause bronchitis?

A
  • Viruses
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis
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10
Q

List some bacterial causes of cavitating lung lesions.

A
  • Staphylococcus aureus
  • Klebsiella pneumoniae
  • TB
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11
Q

What type of bacterium is H. influenzae?

A

Gram-negative cocci-bacilli

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12
Q

How is Legionella spread?

A

Inhalation of infected water droplets

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13
Q

What medium is Legionella grown on?

A

Buffered charcoal yeast extract

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14
Q

Whatis a common feature of bacteria that cause atypical pneumonia?

A

They have NO cell wall

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15
Q

List four atypical organisms.

A
  • Mycoplasma
  • Legionella
  • Chlamydia
  • Coxiella
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16
Q

Which type of antibiotics do not work on atypical bacteria?

A

Penicillins

NOTE: this is because they act on cell walls

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17
Q

Which type of antibiotics do work on atypical bacteria?

A

Antibiotics that interfere with protein synthesis (macrolides, tetracyclines)

18
Q

List some clinical features of Legionella pnaeumophila infection.

A
  • Confusion
  • Abdominal pain
  • Diarrhoea
  • Lymphopaenia
  • Hyponatraemia
19
Q

Urinary antigens are associated with which causes of pnaeumonia?

A
  • Streptococcus pneumoniae
  • Legionalla pneumophila
20
Q

Which investigation is used for Coxiella and Chlamydia psittaci?

A

Serology

NOTE: serology looks at the development of antibodies after an infection (requires paired samples). It is useful for investigating bacteria that are difficult to culture.

21
Q

What is an empyema?

A

Collection of pus within the pleural cavity

22
Q

List some reasons for failure to respond to treatment.

A
  • Empyema/abscess
  • Proximal obstruction (e.g. tumour)
  • Resistant organisms
  • Not absorbing antibiotics
  • Immunosuppression
  • Alternative diagnosis (e.g. lung cancer)
23
Q

What is the classical CXR feature of TB?

A

Upper lobe cavitation

24
Q

Which types of staining are used when investigating TB?

A
  • Auramine staingin
  • Ziehl-Neelsen stain

NOTE: they are red rods

25
Q

Define hospital-acquired pneumonia.

A

A pneumonia that is onset > 48 hours after hospital admission

26
Q

List some organisms that cause HAP.

A
  • Enterobacteriaciae (MOST COMMON - e.g. E. coli, K. pneumoniae)
  • Staphylococcus aureus
  • Pseudomonas
  • Haemophilus influenzae
  • Acinetobacter baumanii
  • Fungi (e.g. Candida)
27
Q

What is Pneumocystic jirovecii pneumonia?

A

Fungus that is ubiquitous in the environment but can cause pneumonia in immunocompromised patients

28
Q

Describe the typical presentation of Pneumocystic jirovecii pneumonia.

A
  • Dry cough
  • Weight loss
  • SOB
  • Malaise
  • Walk test - desaturation on exertion
29
Q

How is PCP investigated?

A

Bronchoalveolar lavage

30
Q

What is the treatment for PCP?

A

Co-trimoxazole (septrin)

31
Q

What are the main features of allergic bronchopulmonary aspergillosis?

A
  • Chronic wheeze
  • Eosinophilia
  • Bronchiectasis
32
Q

What is an aspergilloma?

A
  • Fungal ball often forming within a pre-existing cavity
  • May cause haemoptysis
33
Q

How is invasive aspergillosis treated?

A

Amphotericin B

34
Q

Which organisms cause pneumonia in the following subgroups of patients:

  • HIV
  • Neutropenia
  • Bone marro transplant
  • Splenectomy
A
  • HIV: PCP, TB, Atypical mycobacteria
  • Neutropaenia: Fungal (e.g. Aspergillus)
  • Bone marrow transplant: CMV
  • Splenectomy: Encapsulated organisms (e.g. Streptococcus pnaeumoniae, Haemophilus influenzae)
35
Q

In which organisms is serology useful for reaching a diagnosis?

A

Organisms that are difficult to culture

Examples: Legionella, Chlamydia

36
Q

Which organism is investigated using immunofluorescence?

A

PCP

NOTE: PCP can also be detected using silver stain

37
Q

What is the treatment for mild-to-moderate CAP?

A

Amoxicillin

OR erythromycin/clarithryomycin (if penicillin allergic)

38
Q

What is the treatment for moderate-to-severe CAP?

A

Co-amoxiclav AND clarithromycin

39
Q

What are the 1st and 2nd line treatment options for HAP?

A
  • 1st = ciprofloxacin +/- vancomycin
  • 2nd = tazocin AND vancomycin
40
Q

Which antibiotics are used to treat HAP caused by:

  • MRSA
  • Pseudomonas
A
  • MRSA - Vancomycin
  • Pseudomonas - Tazocin OR ciprofloxain +/- gentamicin