Study On The Antibacterial Activity Of Pseudomonas Aeruginosa Against Candida Albicans In Vitro

Part one Observing the inhibitory effect of Pseudomonas aeruginosa on Candida albicansObjective: To analyze the antibacterial effect of 150 strains of Pseudomonas aeruginosa against Candida albicans ATCC 90028 in vitro.To investigate the effect of Pseudomonas aeruginosa pigment production,colony morphology,and imipenem drug sensitivity on antibacterial activity.Method:1 150 clinical isolates of Pseudomonas aeruginosa were studied,and all of them were cross-streaking method and co-incubation experiments with Candida albicans ATCC 90028 were performed respectively.Observed the inhibitory effect of Pseudomonas aeruginosa on Candida albicans in vitro.2 Observe the pigment production,colony morphology and imipenem susceptibility of the tested strains.Compare the differences in the inhibitory effect of Pseudomonas aeruginosa on Candida albicans ATCC 90028 with three different factors,apply the R×C contingency table chi-square test,Wilcoxon signed rank sum test and Fisher exact test were used for data statistics and analysis.Result:1.In the cross-streaking method,103 strains of Pseudomonas aeruginosa exhibited growth inhibition of Candida albicans,and 47 strains had no effect on the growth of Candida albicans.In co-incubation experiments,the numbers of spores were counted,all 150 Pseudomonas aeruginosa strains showed different degrees of inhibition of growth of Candida albicans.Among150 strains of Pseudomonas aeruginosa,115 were pigment producing strains,35 were not pigment producing strains,11 were mucinous strains,139 were non-mucinous strains,30 were resistant to imipenem,and 120 were sensitiveto imipenem Strains.2.Using R×C contingency table chi-square test or Fisher exact test,analyze Pigment production,colony morphology,imipenem drug susceptibility of Pseudomonas aeruginosa and the result of cross-streaking method respectively.The results showed that the pigment production of Pseudomonas aeruginosa was associated with the antibacterial effect of Candida albicans in the cross-streaking method;different colony morphology of Pseudomonas aeruginosa had a different inhibition rate against Candida albicans in cross-streaking method;however,there was no difference in the inhibition rate of Pseudomonas aeruginosa with different imipenem susceptibility conditions against the Candida albicans in the cross-streaking method.3.Using Wilcoxon signed rank sum test,analyze pigment production,colony morphology,imipenem drug susceptibility of Pseudomonas aeruginosa and the result of co-incubation experiments.The results showed that the ratio of spores of Candida albicans co-incubated with non-producing pigment Pseudomonas aeruginosa was higher than the ratio of spores co-incubated with pigment-producing Pseudomonas aeruginosa;the ratio of spores of Candida albicans co-incubated with mucinous Pseudomonas aeruginosa was higher than the ratio of spores of Candida albicans incubated with non-mucinous Pseudomonas aeruginosa;however,there was no difference in the overall distribution of spores ratio of Candida albicans co-incubated with imipenem resistant or sensitive P.aeruginosa.Part two Inhibition mechanism of Pseudomonas aeruginosa against Candida albicansObjective: Analyze the homology of Pseudomonas aeruginosa,and compare the expression levels of Pyocyanin synthesis related genes phzM and phzS.To investigate the effect of phzM and phzS gene expression on pigment production and antibacterial activity of Pseudomonas aeruginosa.Method:1.The test strains were divided into four groups according to the pigment production conditions and their antibacterial types against Candida albicans:pigment production inhibition group,pigment production non-inhibition group,non-producing pigment inhibition group,non-producing pigment non-inhibition group,pulsed field Gel electrophoresis(PFGE)was performed to analyze the homology of the tested strains in combination with groups.2.The tested strains were selected by group and real-time fluorescence quantitative PCR(RT-qPCR)was used to detect the expression levels of phzM synthesis related genes phzM and phzS.The phzM and phzS gene expression levels of different groups of test strains were compared and analyzed.Result: PFGE results showed that 41 strains of Pseudomonas aeruginosa belonged to 41 different bands,and the similarity coefficients ranged from57.5% to 90.0%,suggesting that the strains are distantly related.RT-qPCR results showed that the expression of phzM was found in 8 strains,and the pigment-producing strain was 105.9% of the non-producing strain,and the strain that inhibited the growth of Candida albicans was 94.4% of the non-inhibited strain;the phzS expression pigment-producing strain was 97.7%of the non-producing strain,and the strain inhibiting the growth of Candida albicans was 107.3% of the non-inhibited strain.Conclusion:1.The pigment-producing Pseudomonas aeruginosa and the non-mucinous Pseudomonas aeruginosa have obvious advantages in inhibiting the growth of Candida albicans,The susceptibility of imipenem of Pseudomonas aeruginosa has nothing to do with the inhibition of Candida albicans.2.41 strains of Pseudomonas aeruginosa had relatively long homology.The expression levels of phzM and phzS genes in the 8 strains tested showed no significant differences among the groups.The phzM and phzS genes are not the only factors that regulate the production of pyocyanin by Pseudomonasaeruginosa,and there is no direct and obvious relationship to the inhibition of Candida albicans.