2000
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)
2001
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)
2002
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)
2002
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:
- Select two disease which might presnt an combination of “peripheral
mass, right middle lobe collapse and prominent hilar lymph nodes” and for
each, describe how these features might be produced. (15 minutes)
- Select one of thse disease and describe the cellular changes that you
expect to be present in the peripheral mass. Outline their pathogenesis.
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)
- Suggest ways in which the introduction of an antiobiotic might have
affected the anticoagulation regime
- What test is routinely used to monitor warfarin therapy?
- Suggest approaches to normalising the coagulation pathway in this
patient
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)
2003
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)
2004:
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?
2005:
Question 1 (11 marks in total)
- Over the last few decades, some bacteria have developed resistance to
certain classes of antibiotics. Briefly outline three mechanisms by which
micro-organisms may become resistant to antibiotics.
- Outline three strategies to reduce the emergence of widespread
antibiotic resistance. (3 marks)
- There are four important bacteria with multiresistance which are common
in many Australian hospitals. List the four bacteria, stating the name in
full. (4 marks)
- Which one of the four is endemic in the majority of Australian teaching
hospitals? (1 mark)
2005
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)
Investigations
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
Serology
EB virus: IgM Pos IgG NegQuestion
12 (6 marks in total)
- Briefly explain any abnormalities in the full blood examination results.
(2 marks)
- Briefly comment on the serology results(4 marks)
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.
2009
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:
- What antioitic is the likely treatment of choise for his streptococcal
throat infection? 1mark
- What factors influence the response of the streptococcus to antibiotic
therapy? 4 marks
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:
- Write notes on the pathophysiology of the immediate or acute symptoms
described above (6 marks)
- The recurrent severe infection in this man suggest possible
immunodeficiency. Suggest the most likely type of immunodeficiency to
explain this infection profile. Give reasons for your answer.
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)