Question 5.
Describe the host cellular responses following exposure to Mycobacterium tuberculosis in an adult who has had previous exposure to TB in childhood.
a) in a healthy individual
(9 marks)
b) in a patient with HIV AIDS
(3 marks)
c) Discuss the interpretation of the mantoux test in screening health workers.

Jack, a 60 year old, previously well, mining contractor who has worked over the past 5 years on assignments in Northern Iraq, returned to Australia 3 months ago. Since his return he has had a productive cough, 3 kg weight loss, night sweats and fatigue. He had a course of amoxicillin for presumed bronchitis but this did not help his symptoms. He also has a 40-year history of smoking 20 cigarettes/day.
On examination he has a low grade fever but does not appear to be in respiratory distress. The chest X-ray shows an opacity in the right upper lobe.
Question 4.
1. Suggest two DIFFERENT pathological processes that are likely to have lead to the opacity of the upper lobe and for each briefly describe the key steps (flow diagram acceptable) leading to development of the mass.
(10 marks)

2. Describe the key microscopic features of each process using the appropriate terminology.
(10 marks)

The laboratory sends a report on the sputum microscopy which reads:
“Positive for acid fast bacilli”
This provides a presumptive diagnosis of tuberculosis (TB)
Question 5.
(a) What is the name of the causative organism?
(1 mark)
(b) What would the laboratory do further to confirm the diagnosis? In what time frame would you expect the results from this to be available and why?
(3 marks)
(c) Describe the principles of anti-microbial therapy of TB (individual drug names not required). Explain how the biology of the TB organism necessitates this treatment approach.
(10 marks)
(d) Give a simple flow diagram describing the mechanism of fever development.
(4 marks)

Question 6.
What is the major mode of transmission of TB? List the necessary precautions to prevent other people being infected by this patient.
(6 marks)
Question 7.
The following are results of a complete blood picture received for this patient, at the time of presentation:


Haemoglobin (Hb) 115 gms/L (reference range 130-175)
Mean Cell Volume (MCV) 85 fl (reference range 8-100)
White Cell Count (WCC) 16.5 (reference range 4-11)
Platelets 450 (reference range 150-450)
Reticulocytes 30 (reference range 20-100)


Film Comment: red cell appearances are normal. Leukocytosis with neutrophilia
(a) What morphological description is given to this type of anaemia?
(1 mark)
(b) Describe the underlying mechanisms which cause anaemia in the clinical circumstances of chronic disease. What tests would you perform to support this diagnosis and distinguish it from other causes of anaemia?
(10 marks)
While under investigation for his TB, Jack remains unwell and spends a week in bed. His fever continues and he physically declines.
(c) Discuss why this patient would be at increased risk of a DVT. Use Virchow’s triad as a framework for this discussion.
(10 marks)