Inhibitory Activity Of ε-poly-lysine Against Non-albicans Candida

Objective To investigate the clinical distribution of non-albicans Candida in a top three hospital in Gansu province.To understand the antibacterial activity of ε-PL on non-albicans Candida,and further explore the antibacterial mechanism of ε-PL on non-albicans Candida.Methods Non-albicans Candida isolated from October 2018 to June 2019 were collected and identified by MALDI-TOF MS;the ability of non-albicans Candida to form biofilms was determined by crystal violet method;the MIC and MFC values of ε-PL against non-albicans Candida were determined by micro dilution method according to CLISI-M27file;the time-growth curve of planktonic strains within 48 h was determined by microturbidimetry;determination of ε-PL by crystal violet method inhibits the formation of non-albicans Candida biofilm and mature biofilm;fluorescence spectrophotometer was used to determine the ROS reactive oxygen species in non-albicans Candida before and after ε-PL treatment.Results Clinically isolated non-albicans Candida were mainly C.tropicalis(27,39.1%),C.glabrata(25,36.2%),C.krusei(11,16.0%)and C.parapsilosis(6,8.7%),with a total of 69 strains.Non-albicans Candida mainly came from oncology(27.5%)and respiratory(17.4%),and were mainly isolated from respiratory tract specimens(31.9%)and blood samples(26.1%).Among all clinical isolates,87%(60/69)were biofilm producers,38%(26/69)were strong biofilm producers,and only 13%(9/69)were unable to form biofilms in vitro.The MIC of ε-PL against C.albicans was 512 μg/mL,and MFC was 1024 μg/mL.The inhibitory effect of-pl on the non-albicans planktonic strain was positively correlated with the drugconcentration,and about 12 hours,ε-PL can play a significant role in bacteria inhibition.ε-PL can effectively inhibit the formation of non-candida albicans biofilms and remove the preformed mature biofilms.The action of ε-PL on C.albicans resulted in the accumulation of ROS,which is the positive correlation with the concentration of the drug;Compared with the blank group,the difference was statistically significant(P<0.05).Conclusion non-albicans Candida were mainly C.tropicalis and C.glabrata,mainly come from oncology and respiratory,and are mainly isolated from respiratory tract specimens and blood samples,and most of them can form biofilms in vitro.ε-PL can effectively inhibit the growth of non-candida albicans and the formation of biofilms,and effectively remove the mature biofilms.Molecular mechanism studies have shown that ε-PL plays an inhibitory role by inducing the rise of ROS.