M8: TB and Respiratory Pathogens

Question 1

What is TB?

Answer 1

• A granulomatous infectious disease caused by Mycobacterium tuberculosis
• Aggregation of macrophages with lymphocytes and some plasma cells

Question 2

What are some symptoms of TB?

Answer 2

• Persistent cough (blood in sputum)
• Fatigue
• Chest pain
• Loss of apetite
• Weight loss
• Fevers and night sweats
• Chills

Question 3

What are some oral manifestations of TB? (4)

Answer 3

• Ulcer on tongue
• Nodules
• Periapical granulomas
• Indurated patches (hard patches)

Question 4

Give some features of mycobacteria (5)

Answer 4

• Aerobic
• Curved/straight rods
• Non-motile
• Acid-fast
• Causes TB

Question 5

How can a Ziehl-Neelsen stain determine TB?

Answer 5

• TB is acid-fast
• Acid-fast cells appear red on a green background during this stain
• Where as non acid-fast cells remain green

Question 6

How do we grow acid fast bacilli?

Answer 6

On Lowenstein-Jensen (LJ) slope

Question 7

How long till growth of TB bacilli is visible on a LJ slope?

What is their appearance like?

Answer 7

• Colonies visible to eye in approx. 8 weeks

Colonies typically ‘rough, buff and tough’

Question 8

How can rapid detection of M. tuberculosis carried out? (2)

Answer 8

• Direct staining of sputum smear and identification

- Nucleic acid amplification techniques (ie PCR)

Question 9

What is the pathogenesis of TB?

Answer 9

• M. tuberculosis survives in alveolar macrophages
• Which causes a cell mediated immune response
• Clinical features of TB due to immune response mediated tissue destruction

Question 10

What occurs during primary TB?

Answer 10

• Initial infection occurs
• Primary complex produced, as well as potential additional foci and spread to other organs
• After about 10 day of primary complex macrophages and T-lymphocytes produced
• Granuloma produced (caseation)
• Reaction causes post primary disease

Question 11

What occurs during post-primary TB?

Answer 11

• Primary complex resolves
• Months/years later reactivation of dormant foci is lobes of the lungs occur
• Large granulomas with caseation occur
• Further spread of and lesions occur

Question 12

TB reaction is likely with who? (3)

Answer 12

• Elderly
• Transplant patients
• HIV patients

Question 13

What type of TB patients are infectious?

Answer 13

Only sputum positive patients are infectious

Question 14

How is Human TB transmitted?

Answer 14

Inhalation in cough droplets from ‘open’ individuals

Question 15

What vaccination can help prevent TB?

What is in the vaccine?

Answer 15

• BCG (Bacille Calmette-Guerin)

- Live, attenuated strain of M.bovis

Question 16

What tests determines whether or not you need a BCG?

Answer 16

• Mantoux/Heaf test

- A lack of inflammatory response from these tests indicates that a BCG is required

Question 17

What are the 2 phases of TB treatment? How long do they last for?

Answer 17

• Intensive phase (2 months)

- Continuation phase (6-9 months)

Question 18

What drugs are administered during the intensive phase of TB treatment? (4)

Answer 18

• Rifampicin
• Isoniazid
• Pyrazinamide
• Ethambutol (used with or instead of Pyrazinamide)

Question 19

What drugs are administered during the continuation phase of TB treatment? (2)

Answer 19

• Rifampicin

- Isoniazid

Question 20

Upper respiratory tract infections include acute inflammatory processes in which parts in the body? (6)

Answer 20

• Nose
• Paranasal sinuses
• Middle ear
• Laryngeal
• Posterior pharynx
• Tonsils

Question 21

What are the causative microbes of upper respiratory tract infections? (2)

Answer 21

• Bacteria

- Viruses

Question 22

Explain what happens during pneumonia?

Answer 22

• Inflammation of bronchial and alveolar spaces
• Anoxia
• Altered cardio-pulmonary functions
• Morbidity/Mortality

Question 23

Give some examples of lower respiratory tract infections (4)

Answer 23

• Pneumonia
• Bronchitis
• Bronchiectasis
• Whooping cough

Question 24

Give some features of Haemophilus Species (6)

Answer 24

• Gram negative rod
• Facultative anaerobes
• CO2 enhances growth
• Catalase +ve
• Oxidase +ve
• Require X or V factor §

Question 25

How many antigenic types of Haemophilus influenzae are there? Which one is the important to us?

Answer 25

• 6 types (a-f)

- Type b

Question 26

Type b Haemophilus influenzae is most associated with what type of disease?

Answer 26

Invasive diseases

Question 27

Give some features of Corynebacterium diphtheriae (2)

Answer 27

• Gram +ve rods

- Person to person spread via nasopharyngeal secretions

Question 28

What is the pathogenesis of Corynebacterium diphtheriae?

Answer 28

• C.diptheriae elicit an inflammatory exudate and cause necrosis of faucal mucosa
• C.diphteriae produce a powerful toxin into the bloodstream which causes cell death

Question 29

What test do we use for distinguishing C.diptheriae?

What do we look for in this test?

Answer 29

• ELEK Test

- Tests for toxin producing microorganisms

Question 30

What is the treatment for C.diptheriae infections? (3)

Answer 30

• Patient isolation
• Antibiotics
• Early antitoxin therapy