Intravenous and inhalational agents: bacterial growth in propofol: practice question

A Anaesthesia question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anaesthesia · Intravenous and inhalational agents: bacterial growth in propofol

Sample item

Propofol syringes and infusion lines must be prepared aseptically and discarded within a few hours of opening. Which property of the formulation makes this necessary?

AIt crystallises at room temperature and blocks the lineBIts glycerol component ferments and produces gas bubblesCThe lipid emulsion supports rapid growth of bacteriaDThe acidic pH degrades it into toxic metabolites

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. The lipid emulsion supports rapid growth of bacteria

Propofol is formulated in a soybean oil, glycerol and egg lecithin emulsion, which is a good culture medium. Contaminated propofol has caused postoperative infections, so strict asepsis and a limited hang time are required.

Option by option

A. It crystallises at room temperature and blocks the line
Propofol emulsion does not crystallise at room temperature.
B. Its glycerol component ferments and produces gas bubbles
Glycerol is added to make the emulsion isotonic and does not ferment.
C. The lipid emulsion supports rapid growth of bacteria (correct)
Correct. The lipid emulsion is a good medium for bacteria, so the infection risk is real.
D. The acidic pH degrades it into toxic metabolites
Propofol is near neutral pH and does not degrade into toxic metabolites on standing.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, The lipid emulsion supports rapid growth of bacteria. Propofol is formulated in a soybean oil, glycerol and egg lecithin emulsion, which is a good culture medium.

Why is "It crystallises at room temperature and blocks the line" not the answer?

Propofol emulsion does not crystallise at room temperature.

Why is "Its glycerol component ferments and produces gas bubbles" not the answer?

Glycerol is added to make the emulsion isotonic and does not ferment.

Why is "The acidic pH degrades it into toxic metabolites" not the answer?

Propofol is near neutral pH and does not degrade into toxic metabolites on standing.

What concept does this question test?

It tests Intravenous and inhalational agents: bacterial growth in propofol in Anaesthesia. Contaminated propofol has caused postoperative infections, so strict asepsis and a limited hang time are required.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Intravenous and inhalational agents: bacterial growth in propofol?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.