Final Exam Exemplar- Short Answer Question
SCENARIO - There has been an out
eak of gastroenteri:s a group of staff and pa:ents in a public hospital ward. The disease
is characterised by watery dia
hoea and abdominal cramps and tenderness. Samples are collected from affected pa:ents
and the cause is determined to be a new strain of the spore-forming Gram posi:ve bacteria Clostridium difficile. This new
strain is found to produce more toxin than previously described strains which appears to
oadened the range of hosts who
maybe suscep:ble to infec:on by this pathogen.
The following THREE ques:ons relate to this scenario.
Q1. Briefly suggest TWO ways in which this pathogen could be being spread among the hospital staff and pa>ents (6 marks,
~60 words) clearly label your responses as 1) and 2).
1) Gastrointestinal pathogen, therefore faecal oral transmission (2 marks) via people not properly washing their hands and
contaminating objects or surfaces (2 marks) which are then touched by a second person and the pathogen is transfe
ed
from the hand to the mouth of the second person.
2) Faecal oral transmission via food (2 marks), poor hygiene as above.
Final Exam Exemplar- Short Answer Ques7on
SCENARIO - There has been an out
eak of gastroenteritis a group of staff and patients in a public hospital ward. The disease
is characterised by watery dia
hoea and abdominal cramps and tenderness. Samples are collected from affected patients
and the cause is determined to be a new strain of the spore-forming Gram positive bacteria Clostridium difficile. This new
strain is found to produce more toxin than previously described strains which appears to
oadened the range of hosts who
maybe susceptible to infection by this pathogen.
The following THREE questions relate to this scenario.
Q2. Would being able to produce spores aid the spread of this pathogen? Explain your answer. (4 marks, ~ 40 words)
Yes (1 mark)
The spores produced by this bacteria are able to survive on objects and surfaces for a long Cme, much longer than
acterial cells without spores. (2 marks)
Also, the spores may not be killed by heaCng/cooking food, so can be a higher risk for food-borne transmission. (1 mark)
Final Exam Exemplar- Short Answer Question
SCENARIO - There has been an out
eak of gastroenteritis a group of staff and patients in a public hospital ward. The disease
is characterised by watery dia
hoea and abdominal cramps and tenderness. Samples are collected from affected patients
and the cause is determined to be a new strain of the spore-forming Gram positive bacteria Clostridium difficile. This new
strain is found to produce more toxin than previously described strains which appears to
oadened the range of hosts who
maybe susceptible to infection by this pathogen.
The following THREE questions relate to this scenario.
Q3. This strain of Clostridium difficile is able to damage intestinal epithelial cells and invade the underlying lamina propria,
esulting in inflammation. Within the lamina propria the bacteria release a toxin “protein A” that induces cell death.
What class of antibody would be best suited to: 1) prevent infection with C. difficile and 2) prevent the action of the toxin?
Briefly justify each of your answers. (4 marks, ~60 words).
IgA would be best suited to prevent infection as it is secreted into the intestinal lumen and can bind and neutralise the
pathogen to prevent it from establishing an infection (2 marks).
IgG would best bind to the toxin in the lamina propria as IgG antibodies can be neutralising i.e. bind to the toxin and
prevent it from acting on host cells and IgG circulates in serum and will be part of the extracellular tissue fluid that
accumulates during inflammation (2 marks).