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Do infusions of midazolam and propofol pose an infection risk to critically ill patients?
M Farrington1, J McGinnes, I Matthews
1Intensive Care Unit, Addenbrooke's NHS Trust, Cambridge.
Abstract:
In order to investigate bacterial contamination of i.v. anaesthetic agents, given by infusion to critically ill patients, we have cultured residual infusion fluid from infusion syringes, 50 containing midazolam and 50 propofol. The infusions had been prepared with routine aseptic precautions and had been running for between 0.75 and 21.25 h. Only scanty growths of Staphylococcus epidermidis were isolated from seven syringes (four midazolam and three propofol). Small volume samples were more likely to produce bacterial growth than large volume specimens. Midazolam infusions made up in 5% glucose were more likely to be contaminated than those made up in 0.9% saline. Antibacterial activity was detected in 18 midazolam and one propofol filtrate. Midazolam infusions inhibited the growth of all seven of the S. epidermidis isolates, whereas propofol supported similar rates of multiplication to that obtained with control broth medium. The results of this study imply that contamination of the infusions probably occurred after they were disconnected from the patient. Despite the ability of propofol to support microbial multiplication, we have no evidence to suggest that this is clinically significant when infusions are prepared with conventional aseptic precautions.
Insights
Bacterial contamination of intravenous anesthetic infusions is rare, with minimal growth of Staphylococcus epidermidis. Midazolam showed antibacterial properties, unlike propofol, suggesting contamination occurs post-infusion.
Area of Science:
- Microbiology
- Critical Care Medicine
- Pharmaceutical Science
Background:
- Intravenous (IV) anesthetic agents are crucial for critically ill patients.
- Assessing bacterial contamination risk in these agents is vital for patient safety.
Purpose of the Study:
- To investigate bacterial contamination in midazolam and propofol infusions used for critically ill patients.
- To evaluate factors influencing contamination and the antibacterial properties of the agents.
Main Methods:
- Culturing residual infusion fluid from 100 syringes (50 midazolam, 50 propofol).
- Assessing contamination based on infusion duration, volume, and preparation solution (5% glucose vs. 0.9% saline).
- Testing antibacterial activity of filtered infusion samples against Staphylococcus epidermidis isolates.
Main Results:
- Scanty growth of Staphylococcus epidermidis was found in 7% of syringes (4 midazolam, 3 propofol).
- Smaller sample volumes and midazolam in 5% glucose were associated with higher contamination likelihood.
- Midazolam filtrates exhibited significant antibacterial activity against all isolates, while propofol did not inhibit growth.
Conclusions:
- Bacterial contamination of IV anesthetic infusions is infrequent when prepared with aseptic techniques.
- Contamination likely occurs after infusion disconnection from the patient.
- While propofol supports microbial growth, it is not clinically significant with standard aseptic precautions.