Microbiological Evaluation of Different Preservative Methods for Amnion Graft

Document Type : New and original researches in the field of Microbiology.

Authors

1 Medical Microbiology and Immunology Department, Ain Shams University

2 El-Fashn General Hospital, Ministry of Health

3 Obstetrics and Gynecology Department, Ain Shams University

Abstract

Background: The use of fetal membranes as a graft has gained a lot of attention since 1910 and ever since it has been used in clinical practice notably in ocular surgeries and in the treatment of burns and skin ulcerations. Amnion graft should be sterile, free of contamination, easily obtained and can be stored for long periods of time without affecting graft integrity. Methods currently used to preserve amnion graft include hypothermic (fresh) storage, freezing, freeze drying and gamma irradiation. For any storage method selected assessing any potential bacterial or fungal contamination is profoundly important to ensure the safety of the stored graft. Objectives: In this study, five different preservative media commonly used in Egypt for storing amnion graft hypothermally were evaluated microbiologically to select the optimum preservation method. Methodology: A total of 40 amnion grafts were obtained from consented women delivered by elective caesarean section. The graft of each donor was split into 7 pieces, two pieces from each donor were cultured immediately after collection to exclude contaminated grafts. The remaining 5 pieces of non-contaminated grafts were stored in five preservative media at 4°C for three weeks: Sodium hypochlorite 0.025% , Glycerol 85%, Gentamycin (0.32 mg/ml) in 100% Phosphate-buffered saline (PBS), Penicillin G (50,000 IU/ 100 ml), and a mixture solution comprised of Streptomycin (50mg/ml), Penicillin (50 mg/ml), and Amphotericin B (2.5 mg/ml) were used for preservation. By the end of each week the pieces were cultured onto aerobic and anaerobic media and the recovered colonies were identified. Results: 25 grafts out of 40 were included in the study. The findings of the study revealed that the contamination was observed in three preservative media, the highest of which was Penicillin G followed by Garamycin and the least contamination proportion was identified in the mixture solution (96% 88% and 44% respectively). The contaminants were mainly Filamentous fungi (69.3%) and Candida albicans (4%) while Staphylococcus aureus was only recovered in two specimens (2.6%). Glycerol 85% and Sodium hypochlorite were free from contamination all over the storage period. Conclusion: The preservation of amnion graft in glycerol 85% and sodium hypochlorite 0.025% were proved to be the optimum media for preservation up to three weeks from a microbiological perspective.

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