A comparison of microbial growth in alfaxalone, propofol and thiopental
F A Strachan1, J C Mansel, R E Clutton
1Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, University of Edinburgh, Roslin, Midlothian EH25 9RG.
Objectives:
To compare the growth of Staphylococcus aureus and Escherichia coli in alfaxalone with that in propofol and thiopental and to evaluate contaminant microbial growth in these agents under two different conditions of storage and handling.
Methods:
Known quanta of S aureus and E coli were inoculated into separate 5 ml samples of propofol, thiopental and alfaxalone. Quantitative bacterial analysis was performed at intervals over a 14 day period. Commercial preparations of propofol, thiopental and alfaxalone were stored and handled using "dirty" or "clean" techniques. Microbial quantification and identification was performed over a 14 day period.
Results:
S aureus and E coli grew rapidly in propofol after six hours. Both bacteria were killed by thiopental. S aureus numbers slowly declined in alfaxalone; E coli growth was rapid after 24 hours. In "dirty" and "clean" groups of intravenous anaesthetics, 9.3 and 7.4 per cent of samples, respectively, were positive for microbial growth; none were considered to represent colonisation of bottles.
Clinical Significance:
Alfaxalone supports growth of some microorganisms but less readily than propofol. Bacterial colonisation of intravenous anaesthetic bottles is uncommon, but contamination as syringes are prepared for injection occurs regardless of storage and handling technique.
Insights
Propofol readily supports Staphylococcus aureus and Escherichia coli growth, while thiopental kills them. Alfaxalone supports some microbial growth, but less than propofol, indicating potential contamination risks with intravenous anesthetics.
Area of Science:
- Microbiology
- Anesthesiology
- Pharmacology
Background:
- Intravenous anesthetics are susceptible to microbial contamination.
- Understanding the growth of common bacteria like Staphylococcus aureus and Escherichia coli in anesthetics is crucial for patient safety.
Purpose of the Study:
- To compare the microbial growth of Staphylococcus aureus and Escherichia coli in alfaxalone, propofol, and thiopental.
- To evaluate contaminant microbial growth in these agents under different storage and handling conditions.
Main Methods:
- Quantitative bacterial analysis of S. aureus and E. coli inoculated into propofol, thiopental, and alfaxalone over 14 days.
- Assessment of microbial growth in anesthetic preparations stored and handled using 'dirty' or 'clean' techniques.
Main Results:
- Propofol supported rapid growth of S. aureus and E. coli within six hours.
- Thiopental demonstrated bactericidal properties, killing both bacterial species.
- Alfaxalone showed slow decline for S. aureus and rapid E. coli growth after 24 hours.
- Microbial contamination was detected in 9.3% of 'dirty' and 7.4% of 'clean' handled samples, though not indicative of bottle colonization.
Conclusions:
- Alfaxalone supports microbial growth, though less readily than propofol.
- Bacterial colonization of intravenous anesthetic bottles is infrequent.
- Contamination during syringe preparation is a risk, irrespective of handling technique.
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