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Effect of storage temperature and pH on the stability of antimicrobial agents in MIC trays
Abstract:
Twelve antimicrobial agents, ampicillin, aztreonam, cefamandole, cefazolin, cefonicid, ceforanide, ceftazidime, ceftizoxime, ceftriaxone, cefuroxime, ciprofloxacin, and norfloxacin, were prepared at pH 6.80 and 7.31 in microdilution trays for storage at 4, -10, -25, and -70 degrees C and for weekly susceptibility testing. All 12 drugs had stable biological activity when stored at -70 degrees C for 1 year. All but ampicillin and aztreonam were stable at -25 degrees C. Storage at -10 degrees C was least satisfactory. Desiccation occurred at 4 degrees C, but short-term storage at this temperature is possible since the antimicrobial agents are stable for up to several months.
Insights
Antimicrobial agents are stable for up to a year when stored at -70°C. Most agents remain stable at -25°C, but ampicillin and aztreonam require colder temperatures for long-term storage.
Area of Science:
- Microbiology
- Pharmacology
- Clinical Laboratory Science
Background:
- Accurate antimicrobial susceptibility testing (AST) relies on the stability of antimicrobial agents.
- Standardized storage conditions are crucial for maintaining the biological activity of AST reagents.
- Variability in storage temperatures can impact the efficacy and reliability of antimicrobial drugs.
Purpose of the Study:
- To evaluate the stability of twelve common antimicrobial agents under various storage conditions.
- To determine optimal storage temperatures for preserving the biological activity of antimicrobial drugs for AST.
- To provide guidance on the long-term storage of antimicrobial agents used in clinical laboratories.
Main Methods:
- Twelve antimicrobial agents were prepared at two different pH levels (6.80 and 7.31).
- Prepared agents were stored at four different temperatures: 4°C, -10°C, -25°C, and -70°C.
- Weekly susceptibility testing was performed to assess the biological activity of the stored agents over time.
Main Results:
- All twelve antimicrobial agents demonstrated stable biological activity after one year of storage at -70°C.
- Eleven of the twelve agents, excluding ampicillin and aztreonam, were stable when stored at -25°C.
- Storage at -10°C yielded unsatisfactory results, and desiccation was observed at 4°C, although short-term storage at this temperature was feasible for several months.
Conclusions:
- Long-term storage of most antimicrobial agents for susceptibility testing is best achieved at -70°C.
- Storage at -25°C is suitable for most agents, with ampicillin and aztreonam requiring lower temperatures.
- Careful consideration of storage temperature is essential to ensure the integrity and efficacy of antimicrobial agents in laboratory settings.