Epithelium of human fresh amniotic membrane has antimicrobial effects in vitro

Abstract

This study was carried out to investigate the antimicrobial effects of human fresh amniotic membrane and human amniotic homogenate supernatant (HAHS) in vitro. Fresh human amniotic membranes were harvested and used to make a cellular amniotic membranes (fresh amniotic membranes without the epithelium) and HAHS. Then, the antimicrobial effects of both the fresh human amniotic membrane with the epithelium and fresh amniotic membranes without the epithelium were observed. The antimicrobial effects of fresh HAHS were examined with Kirby-Bauer method. The antimicrobial capacity was compared with ten antibiotics with the Broth Micro-dilution Method, and the impacts of temperatures and pH values and preserved time of HAHS on the antimicrobial capacity were investigated. Finally, transmission electron microscopy (TEM) was used to explore the possible mechanism of the antibiosis of HAHS. Human fresh amniotic membrane with the epithelium had antimicrobial effects, while fresh amniotic membrane without the epithelium did not have any antimicrobial activities. HAHS showed antimicrobial activities for the three standard strains:Staphylococcus aureus ATCC, Escherichia coli, Pseudomonas aeruginosa; four clinically isolated sensitive bacterial strains: Streptococcus pneumonia, Staphylococcus epidermidis,Staphylococcus haemolyticus, and Proteus mirabilis; three clinically isolated fungal strains:Blastomyces albicans, Fusarium solani, Aspergillus fumigatus; and one clinically isolated multi-drug-resistant strain: Enterococcus faecalis. The minimum inhibitory concentration (MIC) of HAHS for Staphylococcus aureus was less than that of Chloramphenicol, equal to that of Clindamycin, greater than that of Penicillin, Rifampicin, and Levofloxacin. Fresh amniotic membrane with epithelium and HAHS had antimicrobial activities, and fresh amniotic membrane without the epithelium did not, indicating that antimicrobial activities are related with the epithelium. HAHS had broad antimicrobial activities and stable characteristics. The mechanism of antimicrobial effect of HAHS was probably interacting with the plasma membrane of the bacteria. Key words: Human amniotic membrane, antimicrobial effects, amniotic homogenate supernatant, minimum inhibitory concentration, minimal bactericidal concentration.