A 65-year-old man is brought to the Accident and Emergency Department (“AED”) by his wife, complaining of shortness of breath. Five days prior to the presentation he felt unwell and complained of muscle aches and headaches. He self-treated himself with over-the-counter tablets for the common cold and flu. He started having rigours and his wife measured his temperature as 39°C. However, his symptoms worsened, and by the day of presentation, he was complaining of a dry cough and marked shortness of breath. He had also become confused. He is a non-smoker with no significant past medical history.

On examination, the patient looks unwell, dehydrated and flushed. His temperature is 39.5°C. Upon admission to the ward, a chest X-ray showed a diffuse pattern of infiltrates. He was given a high concentration of inspired oxygen and intravenous empiric antibiotics, ceftriaxone and clarithromycin.

a) List THREE common ingredients of over-the-counter tablets for ‘common cold and flu” and state its function. (6 marks)

b) Which group of antibiotics do ceftriaxone and clarithromycin belong to respectively? (2 marks)

c) What are the advantages of intravenous instead of oral antibiotics are given to this patient? (2 marks)

d) State the mechanisms of action for ceftriaxone and clarithromycin respectively. (6 marks)

e) Name TWO common mechanisms of resistance that may develop with ceftriaxone and clarithromycin respectively. (4 marks)