Question 2.
Explain the course of infection by encapsulated bacteria in humans eg; pneumococcus. How does the capsule modify host responses to infection and how does tissue damage occur?
(20 minutes)

Question 2.
a) Over the last few decades, some bacteria have developed resistance to certain classes of antibiotics. Briefly outline some mechanisms by which micro-organisms may become resistant to antibiotics.
(9 minutes)
b) Outline strategies to reduce the emergence of widespread antibiotic resistance?
(3 minutes)

Question 3:
An outbreak of a febrile illness without localising signs occurs in your hospital. The laboratory technicians are asked to try and distinguish the pathogen as a virus vs. a bacterium. What do you know about the structural and growth characteristics of viruses and bacteria that could help in establishing a causative agent?
(15 minutes)
Questions 4:
Outline the biological mechanisms leading to a fever.
(10 minutes)

A 68 year old man who is receiving warfarin therapy for atrial fibrillation and who has a long history of chronic bronchitis (ex smoker, presents to his GP with fever and worsening cough. He has been brining up large amount of green sputum for three days.

Examination reveals a febrile elderly man in moderate respiratory distress. He has scattered wheezes through his chest, which is hyper-expanded in keeping with chronic obstructive airway disease. Pulse is 92/min irregularly irregular. BP is 140/80.

Question 6:
What routine microbiological tests would help identify and characterise the pathogens responsible for this mans signs and symptoms. In your answer, give examples of likely pathogens and how they might be identified.
(12 minutes)
The patient is treated with 2 week course of amoxicillin, bronchodilator therapy and chest physiotherapy. He presents one week after completing his antibiotic course stating that he has not improved. He has lost 4kg in weight over the past month.

Question 7:
Suggest reasons why his symptoms might be persisting despite several weeks of treatment.
(6 minutes)
Question 8:
In what way might smoking have interfered with his hose defences?

The doctor is surprised amoxicillin has not helped, as sputum culture grew haemophilus influenza sensitive to amoxicillin and the patient has taken his medication regularly. She orders a chest x ray:

Chest X ray report:
There is collapse of the right middle lobe. Prominent hilar(central) lymph nodes noted. Peripheral lung mass 2cm x3cm.

Question 9:
The treating physician wants to biopsy the mass bt the patient is at an increased risk of bleeding from the procedure.

Question 10:
Briefly explain how wafarin affects the coagulation pathway. (4 minutes)

As part of the diagnostic workshop a blood picture is done and shows the following.
Hb 85g/L (130=175)
MCV 92fL (82-98)
WCC 2.0x109 (4-11)
Neutrophils 0.5x109/L (1.8-7.5)
Lymphocytes 1.5x109/L (1.5-4.5)
Pl. 35,000 (150,000-450-000)

Question 11:
Analyse the blood findings and discuss possible underlying mechanisms. (15 minutes)

A 53 year old man was found by his relatives at home, unresponsive but with a continuous epileptiform (seizure) movements. He has a long history of alcoholism and for several days prior to this seizure he had been drinking heavily. On arrival in the emergency department he had a temperature of 38.5 degrees C, a stiff neck and did not respond verbally to verbal stimuli.

Question 7:
Give three possible explanations for this clinical picture and explain your reasoning. (6 minutes)
Question 8:
What tests used in common practice would help to differentiate between your hypotheses? Give reasons for your choices. (6 minutes)

On further examination he had a temp of 39 degrees C, a heart rate of 130bpm, respiratory rate of 30/min and some crepitations were heard over the right chest wall. He had a chest x ray which showed consolidation in the right middle and upper lobes of the lung.

A full blood exam showed:
Hb 155g/L (130-175)
WBC 18.7 x 109 /L (4-11)
93% neutrophils
Neutrophils show toxic granulation and a shift to the left.

Question 9:
What information is gained from these blood test results and what is their significance to the clinical presentation? Explain the mechanisms leading to such a result. (8 minutes)
Blood cultures grew a gram positive diplococcic from the aerobic bottle.
Question 10:
What is the most likely organism causing his pneumonia (2 minutes)
Question 11:
Describe the mechanisms used by this micro-organism to overcome host defences, establish an infection and cause disease.
Question 12:
Discuss inflammatory changes in the lung during the development of his pneumonia (15 minutes)

Due to his reduced level of consciousness a full systems examination could not be carried out. He had a CT scan of the head which was normal. This was followed by a lumbar puncture which showed large numbers of polymorphs and on microscopy, gram positive diplococcic.
He was started on IV benzylpenicillin
Question 13:
What diagnosis do these results suggest? Do you think that his 2 acute conditions are linked? How so? (3mins)
Question 14:
Discuss the mechanism of action of bea-lactams and how resstance ot these antibiotics develops. (15 mins)
Question 15:
Suggest ways to overcome penicillin resistance. (5mins)
Question 16:
Describe the vaccine available for prophylaxis against his infection and give the main indications for hits use in the community. (5minutes)


Zac’s parents seek medical help 24 hours later when Zac’s foot is even more swollen, with blistering near the puncture site. Zac is irritable and febrile. One of the blisters weeps a blood-stained purulent fluid which is swabbed and sent for microscopy, culture and sensitivity. Microscopy shows Gram positive cocci in clumps with neutrophils and debris.
Zac is given a tetanus toxoid injection.
Question 8.
a) Which is the most likely micro-organism based on the microscopy findings?
(1 mark)
b) Explain the principles of laboratory testing involving “microscopy, culture and sensitivity”.
(6 marks)
c) Suggest an appropriate antibiotic for this micro-organism and briefly outline its mode of action.
(4 marks)
Question 9.
Compare and contrast the immunological events following an injection of tetanus toxoid
a) if Zac had not received his routine immunizations in infancy i.e. has never had tetanus toxoid before.
(10 marks)
b) if Zac’s immunizations were up to date.
(10 marks)
Question 10.
Zac’s foot remains swollen, red and hot 48 hours after antibiotics were prescribed.How might the poor response to antibiotics be explained?

Question 1 (11 marks in total)


A 7-year-old girl, Sally, is brought to her General Practitioner’s surgery by her mother who has noticed that her daughter has been lethargic for several days and has a high temperature. Sally has refused to eat for 24 hours because of pain on swallowing.
On examination Sally appears flushed and subdued. Temperature 39 C Her pulse rate is increased at 120/min, chest clear. Nostrils patent, no nasal discharge. Throat: reddened pharynx with prominent tonsillar exudate overlying very large tonsils. Prominent tender lymph nodes in upper neck. Lymph nodes in axillae and groins readily palpable. Spleen also just palpable.
Question 8
Suggest 3 pathogens which would be most likely to cause this symptom complex.
(3 marks)
Question 9 (9 marks in total)
Briefly explain the processes that result in the redness, pain and swelling of the tonsils(3 marks)
Briefly explain the process that leads to the fever(2 marks)
Explain why Sally has palpable lymph nodes and a palpable spleen(4 marks)
Question 10
Describe two tests which could be carried out on a throat swab which could confirm or exclude possible pathogens. (4 marks)

Question 11
List three other tests which you might perform. Give reasons for your choices. Of these other tests, which 2 would be of most value? (5 marks)



Throat swab – microscopy, culture and sensitivity: Numerous degenerate polymorphs Normal oral flora


Full Blood Examination
Haemoglobin 131g/L (115-160)
MCV 83fL (80-100)
WCC 9.3 x 109/L (4.0-11.0)
Neutrophils 4.0 x 109/L (1.5-7.5)
Lymphocytes  3.2 x 109/L (1.0-5.0)
Monocytes 2.0 x 109/L (0.2-0.8)
Eosinophils 0.1 x 109/L (0-0.4)
Platelet   330,000 (150-400,000)

Film shows 20% atypical mononuclear cells         No blasts seen

EB virus:  IgM     Pos    IgG      NegQuestion 12 (6 marks in total) 2008
Question 2.
A 22 year old university student presents to her GP with a sore throat, fever and tender cervical lymph nodes. You decide to take a throat swab because you suspect a bacterial infection.
(a) Describe the steps the microbiology laboratory takes to reach a microbiological diagnosis.
(6 marks)
(b) Name a common organism involved in bacterial throat infections.
(1 mark)
(c) Name one antibiotic that can be used to treat this infection?
(1 mark)
(d) What is the mechanism of action of this class of drugs?
(3 marks)
(e) List the broad categories of antibiotic resistance mechanisms that bacteria may enlist.
(3 marks)

Question 3.
List 4 possible sequelae of the acute inflammatory process. Give an example for each.

Mr. Brooks, a 65 year old man presents to his general practitioner with a neck swelling that he has had for approximately 2 weeks. He comments that he has been unwell with an illness that started with a sore throat and fever, followed by the development of a productive cough and worsening fever in the last few days. This was associated with general tiredness and loss of appetite. His concern is that the swelling in his neck is getting lager.
On examination you discover the neck swelling to be a tender, enlarged lymph node approx. 1.5cm in size which you recognize as abnormally enlarged and associated with several other smaller non tender palpable lymph nodes. He is febrile with a temp of 37.8C and examination of his throat reveals some signs of inflammation of his tonsils. Chest auscultation is clear.
He admits to smoking 1 packet of cigs a day for 40 years and to losing 8kg in weight over the last 3 months.
Question 4:
Suggest 2 reasoned hypotheses for the pathologically enlarged lymph nodes you have discovered in the mans neck. (8 marks)

Question 5:
Briefly describe the signs and symptoms of acute inflammation using examples from or reference to the case above where possible. (10 marks)
Results of a full blood count 
Hb 100g/L 120-160
MCV 85fL 80-100
Riticulocyte count 19 20-100
WCC 16 8-12
Platlet count 266 150-450


White cell differential reveals neutrophilia of 12x109/L with toxic granulations

Question 6:
Outline the abnormalities int he above full blood count results. (4 marks)

A throat swab taken from this patient and laboratory results reveal a streptococcus secies.
Plasma creatinine 220mmol/L (60-110 mmol/L)
Iron studies:
Ferritin 350 micrograms/L (20-300)
Serum Iron 25 micromol/L (8-30)
Transferrin 2.2g/L (2-3.6)
Transferrin saturation 48% (10-50)

Question 7:

Using all of the information in his test results write short notes to explain possible mechanisms for the abnormalities in his complete blood picture. (9 marks)
Question 8:

The patient responds to your choice of antibiotics with prompt resolution of fever and improvement of all other symptoms.
Over the next six months the patient has several sinus and chest infections, culminating in a further admission with pneumococcal pneumonia. Within minutes of receiving intravenous antibiotic he develops widespread itchy welts, dizziness and wheeze.
Question 9:

However, on futher follow up Mr. Brooks continues to cough and lose more weight. Chest x-ray now demonstrates a solitary lung nodule. The pathology report for the biopsy describes the lesion as moderately differentiated adenocarcinoma. Staging of the turmour will require a surgical specimen and clinical information.
Question 10:
What is the purpose and significance of typing, grading and staging in cancer diagnosis. (4 marks)

June 2010:
Question 7.
Give an example of a chemical mediator in an acute inflammatory reaction. What is its function?
(3 marks)