M8: TB and Respiratory pathogens

Question 1

What is tuberculosis?

Answer 1

A granulomatous infectious disease caused by Mycobacterium tuberculosis

Question 2

What are the symptoms of tuberculosis?

Answer 2

Persistant cough (blood in sputum)
Fatigue
Chest pain
Loss of appatite
Weight loss
Fevers and night sweats
Chills

Question 3

what is a granuloma?

Answer 3

a chronic inflammatory reaction, predominantly
of activated macrophages – aggregation of macrophages
with lymphocytes and some plasma cells.
- cheese like

Question 4

what are the oral manifestations of TB?

Answer 4

Ulcer on tongue (also less often on any oral mucosal site).
Nodules, periapical granulomas, indurated (hardened) patches.
Oral lesions can be overlooked in the absence of systemic symptoms

Question 5

Give the characteristics of mycobacteria

Answer 5

Aerobic,
curved/straight rods, non-motile
Acid-fast - Cell wall contains ‘waxy’ lipids (mycolic acids)
Causes TB in humans

Question 6

What colour do Acid fast calls stain on a green background?

Answer 6

red (rods/bacilli)

other bacteria that are non-acid fast stain green

Question 7

Give the characteristics of the growth of TB

Answer 7

slow growing
colonies (visible to the eye after 8 weeks) are typically ‘rough, buff (ie pale yellowish) and tough’
temp. range of growth: 35-37 ºC

Question 8

What is a biomarker

Answer 8

a substance/structure/process that can be measured in the body or its products and influence/predict the incidence of outcome or disease

Question 9

what are the 4 closely related speciec that can cause mammalian TB

Answer 9

1. M.tuberculosis (Human)
2. M.bovis (bovine – also human and other mammals)
3. M.africanum (human, mainly found in equatorial Africa)
4. M.microti (vole – seldom encountered)

Question 10

what are the 2 main forms of TB

Answer 10

primary & post-primary

Question 11

explain the stages of primary infection

Answer 11

1. Initial infection (lungs)
2. M. tuberculosis replicates via macrophages
3. Macrophage carries disease to hilar lymph node = additional foci; ghon focus; spread to other organs & tissues
4. 10 days+ T-lymphocytes produce; lymphokines; macrophages
5. GRANULOMA (cheese-like cessation)
6. Limits primary infection, but mycobacteria persists within = POST PRIMARY DISEASE

Question 12

explain the stages of post-primary TB

Answer 12

1. Reactivation of dormant foci in lobes of lungs
2. Large granulomas with caseation
3. Tuberculoma expands onto bronchus = bacilli in sputum & further spread & lesion

Question 13

what patients are mire suscptible to post-primary TB

Answer 13

HIV px; elderly; transplant px

Question 14

post-primary TB is cause be the reactivation of _______

Answer 14

dormant foci in the lobes of the lungs

Question 15

Tuberculoma expands into the bronchus in post-primary TB. T/F?

Answer 15

T

Question 16

how is TB transmitted

Answer 16

Droplet inhalation from ‘open’ (sputum +ve) individuals

Question 17

What is the vaccination for TB and what is its efficacy?

Answer 17

BCG (bacille calmette-guerin)
Intracutaneous injection
Variable efficacy – better in children, variable in adults

Question 18

What drugs are given to the px in the intensive 2 month phase, and in the continuous 6-9 month phase to treat TB?

Answer 18

intensive phase: 
Rifampicin,
Isoniazid
Pyrazinamide (and/or
Ethambutol)

continuation phase:
Rifampicin
Isoniazid

Question 19

What are the stages of Pneumonia?

Answer 19

Inflammation of bronchial and alveolar spaces -> Anoxia -> Altered cardiopulmonary
functions -> Morbidity/Mortality

Question 20

Name the bacteria found in:

1. Acute and chronic bronchitis
2. bronchiectasis
3. whooping cough

Answer 20

1. Bronchitis
Acute: 
-Mycoplasma pneumoniae
Chronic:
-H.influenzae
-S.pneumoniae
2. Bronchiectasis (weakened and dilated bronchus)
H.influenza
Ps.aeruginosa (anaerobes)
3. Whooping Cough
B.pertussis

Question 21

what type of pathogens can cause primary pneumonia?

Answer 21

Streptococcus pneumoniae
Yersinia Pestis (Pneumonic plague)
Klebsiella pneumoniae
Bacillus anthracis (anthrax)
Legionella pneumophilia (Legionnairesdisease)
(Mycoplasma, Chlamydia)

Question 22

what type of pathogens can cause secondary pneumonia?

Answer 22

Strep. pneumoniae
Haemophilus influenzae
Branhamella catarrhalis
fungal infections

Question 23

what are haemophilus species?

Answer 23

-gram -ve rod; pleomorphus = coccobacillus/filamentous shape
-facultative anaerobes
• CO2 enhances growth
• Catalase +ve
• Oxidase +ve
-requires X factor (haemin) and/or V factor NADP

Question 24

how many antigenic types of haemphilus influenza are ther and which is the most important?

Answer 24

6,
B

• Capsular type b strains are most frequently
associated with invasive disease

Question 25

Haemophilus influenzae

Answer 25

Carriage
• Upper resp. tract (nasopharynx/throat)
• Non capsulate stains in 25 – 80% healthy individuals
• Capsulate strains in 5 – 10% healthy individuals
• Type b strains in 1 – 5% healthy individuals
Pathogenesis
• Important in young children ( 2 months to 2 years especially)
• Possibly penetration of submucosa of nasopharynx by H.influenzae
• Occasionally causes pulmonary disease in adults
with preceding viral infection or chronic bronchitis
Otitis Media
• Frequently caused by non-typable strains although
pathogenesis is unclear
Virulence factors
• Capsule – antiphagocytic
• Pili (fimbrae) – attachment to epithelial cells
• IgA protease
• Other cell membrane components
Non-invasive disease
• Usually non-encapsulated strains
• Often predisposition (viral, anatomical)
• Local infection
Otitis media
Sinusitis
• Can give chronic obstructive airway
disease

Question 26

what are the characteritics of corynebacterium diphtheriae?

Answer 26

• Causes diphtheria
• Gram +ve rods – diptheroids or
coryneforms (pleomorphic rods which may stain irregularly ‘Chinese Lettering!’)

Aerobic/facultative anaerobic

Question 27

how is corynebacterium diphtheriae spread?

Answer 27

Person to person spread via nasopharyngeal
secretions;
children are particularly susceptible

Question 28

how can corynebacterium diphtheriae cause respiratory obstruction?

Answer 28

C.diptheriae elicit an inflammatory exudate
and cause necrosis of faucial mucosa (Fauces: opening leading from mouth to pharynx)
Infection may spread to post-nasal cavity of
larynx and cause respiratory obstruction.
+
Clotting of exudate which becomes adherent –
pseudomembrane

Question 29

what is the treatment for diphtheria

Answer 29

px. in isolation; antibiotics given: Pencillin, Tetracycline, Clindamycin

Question 30

what tests allow you to differentiate between different toxigenic strains
from commensal corynebacteria

Answer 30

• Elek Test

* Schick Test