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Efficacy of penicillin G, cefazolin, and gentamicin in M-K medium at 4 degrees C
Abstract:
Corneal-scleral shells are routinely stored in McCarey-Kaufman (M-K) medium at 4 degrees C. Antibiotics are added to the medium to suppress bacterial growth. We examined the antibacterial activity of penicillin G potassium, 100 microgram/ml, cefazolin sodium, 100 microgram/ml, and gentamicin sulfate, 20 microgram/ml against test organisms in M-K medium at 4 degrees, 23 degrees, and 37 degrees C for periods up to 18 hours. Within the limits of the experimental conditions, none of the antibiotics used could be relied on to sterilize an inoculum of sensitive bacteria in M-K medium at 4 degrees C, the recommended storage temperature.
Insights
Antibiotics like penicillin, cefazolin, and gentamicin do not reliably sterilize corneal storage medium at recommended temperatures. This study highlights concerns for bacterial contamination in eye banking practices.
Area of Science:
- Ophthalmology
- Microbiology
- Biotechnology
Background:
- Corneal-scleral shells are critical for sight-restoring transplants.
- McCarey-Kaufman (M-K) medium is the standard storage solution for corneal tissue.
- Preventing bacterial contamination during storage is essential for graft survival.
Purpose of the Study:
- To evaluate the antibacterial efficacy of commonly used antibiotics in M-K medium.
- To determine if standard antibiotic concentrations can prevent bacterial growth at various temperatures.
- To assess the reliability of antibiotic prophylaxis in eye banking.
Main Methods:
- Antibacterial activity testing of penicillin G potassium, cefazolin sodium, and gentamicin sulfate.
- Inoculation of M-K medium with test bacteria.
- Incubation at 4°C, 23°C, and 37°C for up to 18 hours.
- Assessment of bacterial growth inhibition.
Main Results:
- None of the tested antibiotics (penicillin G, cefazolin, gentamicin) demonstrated reliable sterilization of M-K medium against sensitive bacteria at 4°C.
- Antibacterial activity was limited under the experimental conditions, even at higher temperatures.
- The recommended storage temperature of 4°C showed reduced efficacy for the tested antibiotics.
Conclusions:
- Current antibiotic concentrations in M-K medium may not be sufficient to prevent bacterial contamination in corneal storage.
- Relying solely on these antibiotics for sterilization at 4°C is not advisable.
- Further research into alternative or enhanced antimicrobial strategies for corneal storage is warranted.