Study On The Antibacterial Activity Of Prodigiosin Against Staphylococcus Aureus

Objective1.By analyzing the distribution and bacterial resistance of Staphylococcus aureus strains isolated clinically from Jiaxing First Hospital from 2020 to 2021 and testing the Minimum Inhibitory Concentration(MIC)of PG,the antibacterial effect and mechanism of prodigiosin on Staphylococcus aureus were analyzed and studied.This study provides a basis for the research and application of new clinical antibacterial drugs.Methods1.Retrospectively analyze the isolation and drug resistance characteristics of Staphylococcus aureus isolated clinically from Jiaxing First Hospital from 2020 to 2021.2.The standard strain of Staphylococcus aureus ATCC25923,methicillin-resistant Staphylococcus aureus USA300 and 164 Staphylococcus aureus strains isolated clinically were used as study target strains.The minimum inhibitory concentration(MIC)of prodigiosin against different strains was detected by the micro-broth dilution method.3.The MIC values of prodigiosin under the combined action of levofloxacin,cefazolin and erythromycin were detected by the checkerboard method,and the combined inhibitory index FIC value was calculated.4.Staphylococcus aureus standard strain ATCC25923,methicillin-resistant Staphylococcus aureus standard strain USA300 and 1 clinical isolate(number21609490)were processed with sub-inhibitory concentration(1/8 MIC)of prodigiosin,and the changes of cell membrane structure were observed by transmission electron microscope.5.The USA300 and clinical isolate(21609490)were processed with sub-inhibitory concentration of prodigiosin(1/8 MIC)respectively as the experimental group.Through transcriptome sequencing,the differential genes of in the experimental group and the control group were screened and clustered by KEGG pathway analysis.Results1.From 2020 to 2021,1408 strains of Staphylococcus aureus were detected.The specimens with the highest detection rate were respiratory specimens,followed by wound surfaces,wounds,and blood specimens;Orthopedics,burns,and general surgery were the main infection departments,the follows departments were ICU and Pediatric The detection rate of MRSA in the Staphylococcus aureus detected was 19.53%,and the detection rate of MSSA was 80.47%.The resistance rate of MSSA strains to penicillin G was as high as 82.17%,and the resistance rate of MRSA to penicillin G was 100%.All strains have high resistance rates to erythromycin,clindamycin,etc.There wrer no strains resistant to vancomycin.2.Promycoerythrin had bacteriostatic effect on both MRSA and MSSA groups.The MIC50 of the MRSA group was 0.5 μg/mL,and the MIC90 of tne MRSA group was 1μg/mL;however both the MIC50 and MIC90 of the MSSA group were 0.5 μg/mL.The MIC value distribution between the two groups was significantly different(x2=14.66,P<0.01).3.When prodigiosin combined with erythromycin,it had a good antibacterial effect,and about 70%showed synergistic and additive effects,followed by the synergistic effect with levofloxacin,and the synergistic and additive effects accounted for 56.63%.When prodigiosin combined with ceftazole,the synergistic effect was less,and 67.47%were irrelevant.4.Under the action of prodigiosin at sub-inhibitory concentration(1/8 MIC),Staphylococcus aureus cells shrunk,and Gram staining deepened.Under electron microscope,the space between bacterial cells increased,cell membranes shrunken and ruptured,and even completely broken into small fragments,the structural damage is more obvious than that of the control group.5.The action of sub-inhibitory concentration(1/8 MIC)prodigiosin,the transcriptome genes of Staphylococcus aureus were up-regulated and down-regulated,such as gene sarA,genes glmS and adhP;and the genes with differential changes were mainly involved in the metabolic pathways and membrane protein synthesis pathways.Conclusions1.In this study,Staphylococcus aureus was commonly detected in the surgical department,and the MRSA ratio was close to 20%.The antibiotics with high drug resistance were mainly penicillin G,quinolones,erythromycin and clindamycin.2.Prodigiosin has a certain bacteriostatic effect on MRSA and MSSA strains,and the MIC value between different strains is slightly different.3.The combination of prodigiosin and erythromycin has the best effect,followed by quinolones and cephalosporins.4.This study found that the bacteriostatic effect of sub-inhibitory concentration of prodigiosin on Staphylococcus aureus was mainly the cell membrane,and prodigiosin could destroy the structural integrity of the cell membrane.5.The co-incubation effect of sub-inhibitory concentration of prodigiosin on Staphylococcus aureus in this study was mainly through down-regulating the membrane-related gene sarA and up-regulating the metabolism-related genes glmS and adhP,resulting in rupture of the membrane of the bacterium and inhibition of growth.