Question

Question 2
Mrs. Wong, a 75-year-old woman, is admitted to the hospital with community-acquired pneumonia
(CAP) suspected of a bacterial cause. She has a long history of diabetes requiring regular medical
treatment. Mrs. Wong is experiencing typical signs and symptoms of pneumonia including shortness
of breath, high fever, cough with purulent sputum, etc. and she looks very ill. A sample of sputum
has been sent for laboratory investigation together with other diagnostic tests completed including
chest X-rays. With the high risk of developing systemic infection in Mrs. Wong, the doctor therefore
prescribed broad-spectrum beta-lactam antibiotics for her while waiting for the test results to further
confirm her diagnosis.
a. Describe THREE factors that must be evaluated by the doctor when prescribing antimicrobial
treatment for Mrs. Wong. Explain each of them in details and provide rationales (or examples) to
support your answer as necessary.
b. Differentiate between broad-spectrum and narrow-spectrum antibiotics. Describe the antibacterial
actions of broad-spectrum beta-lactam antibiotics and suggest ONE example of drug from this
class that is more likely to be effective in treating the CAP of Mrs. Wong.
c. The laboratory report confirmed that the CAP of Mrs. Wong is caused by the most common
infectious agent. Suggest ONE type of systemic infection that can be caused by this agent and
describe the clinical presentation of this condition. Name TWO virulence factors of this infectious
agent and briefly describe how they contribute to the pathogenesis of infection in Mrs. Wong. (10
marks)
~ END

Answer 1

a)

1.- The age of the patient. The pharmacokinetics change in older people, so we have to pay special attention to doses

2.- The diabetic condition. Certain antibiotics may cause harmful effect on diabetic people, interfering with sugar fluctuations.

3.- The interaction between drugs. The patient is already taking medical treatment, we have to check what is she taking to evaluate what are we going to prescribe

b) Broad spectrum antibiotics are the ones that interfere with a metabolical pathway that is generally found in many bacterial species, thus it works against many types of infections, contrary to that, the narrow spectrum antibiotics are specialized to just a few species or only one.

Beta lactm antibiotics are broad spectrum because they interfere with a very common pathway in bacteria: the production of peptidoglycan cell wall. The cell wall production is disrupted, thus the cells cannot correctly reproduce.

Beta lactams are not the most suggested antibiotics against CAP, macrolides are, but amoxicilline is one beta lactam that is used in some cases to treat it.

c) The most common infection agent is Streptoccocus pneumoniae. This agent can produce necrotizing neumonia, which is a systemic infection known for developing necrosis in the lungs that may spread to surrounding tissues.

This bacteria has many pathogenic factors, like the development of a capsule that prevents it from being phagocytated, the presence of adhesins which help it attach to the tissues, between others.