Study on the preparation and antibacterial sensitization of epigallocatechin gallate and its nanoparticles

Objective: To study the antibacterial and drug sensitizing effects of epigallocatechin gallate (EGCG)and its nanoparticles on 6 kinds of clinically common multi-drug-resistant organisms.Methods: Six multi-drugresistant organisms isolated from clinical samples were selected.The isolates were methicillin-resistant Staphylo-coccus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), multi-drug-resistant Acineto-bacter baumannii(MDR-Aba), multi-drug-resistant Pseudomonas aeruginosa(MDR-Pae), ESBL-producing Esch-erichia coli (ESBL-Eco) and ESBL-producing Klebsiella pneumoniae (ESBL-Kpn).Broth dilution method was used to determine the minimum inhibitory concentration (MIC) of EGCG and its nanoparticles, and the 22 h growth curve of bacteria was drawn.Live bacteria coating method was used to determine the minimum bactericidal concentration(MBC).The chessboard di-lution method was used to determine the combined effect and sensitization effect of EGCG and its nanoparticles in combination with 7 antibacterial drugs(clindamy-cin, cefoxitin, penicillin, levofloxacin, amtrexone, ceftriaxone, ampicillin/sulbactam).Results: The MIC of EGCG against 6 multi-drug-resistant organisms was 350 μg/mL-500 μg/mL, and the MBC was 350 μg/mL-700 μg/mL.The MIC of EGCG nanoparticles against 6 multi-drug-resistant organisms was 62.5 μg/mL-125 μg/mL, and the MBC was 175 μg/mL-350μg/mL.This indicated that the MIC and MBC of nanoparticles were lower, and the growth curve also indicated that nanoparticles significantly delay the logarithmic growth period of bacteria.The combined effects of EGCG and antibacterial drugs were synergistic or additive, and the combination with the best sensitization effect was that EGCG restored the sensitivity of MRSA to cefoxitin, and that EGCG restored the sensitivity of MDR-Aba to levofloxacin; the combined effects of EGCG nanoparticles and antibacterial drugs were mainly additive, and the combination with the best sensitization effect was that EGCG nanoparticles re-stored the sensitivity of MRSA to cefoxitin and penicillin.Conclusion: EGCG and its nanoparticles have antibac-terial activity against 6 kinds of multi-drug-resistant organisms.The antibacterial effect of EGCG nanoparticles alone is better than that of EGCG.The combination of EGCG and its nanoparticles with 7 antimicrobial drugs can increase the sensitivity of drug-resistant organisms.