Study On Correlation Between Twitching And Carbenicillin Resistance In Pseudomonas Aeruginosa

With bacteria becoming increasingly developing resistance to antibiotics,multiple drug-resistant strains are constantly emerging.As one of the leading pathogens in nosocomial infections,there are many multiple drug-resistant strains deriving from P.aeruginosa frequently,which makes it difficult to cure.Mobility plays a vital role in the colonization of pathogens and the formation of biofilm which is one of the main reasons of resistance.In the early stage of the experiment,we found when clinical isolated strains showed reduced twitching most of which were resistant to carbenicillin,while a partial of pili-related genes did not show antibiotic resistance after mutating.Besed on the above research,we further explore whether there is a certain correlation between carbenicillin and twitching.There are two methods in our study.Firstly,constructing pili-related genes and regulatory genes,we can confirm whether twitching-related genes which are coded by pili have an effect on the resistance of the strain to carbenicillin.Secondly,a twitching-reduced transposon insertion library will be constructed and then the strains which are sensitive or resistant to carbenicillin will be screened to confirm whether they are related to pili.In the study,we chose 13 genes or operon to delete,which are pil PONM?pil Q?pil F?pil T?fim V?pil K?pil RS?cpd A and so on.Related phenotypes and TEM showed that only ?cpd A was sensitive to carbenicillin while its twitching had no obvious difference with the wild type.However,others were just the opposite.What,s more,we also detected the sensitivity to additional 16 kind of antibacterial agents and only ?cpd A had different sensitivity to antibacterial agents.We constructed a transposable mutant library covering about 6 times of the genome,including 41000 clones.We obtained 21 strains which both influence to twitching and carbenicillin.Meanwhile we also detected the sensitivity to additional 16 kind of antibacterial agents.The results showed these strains also almost showed the same sensitivity to additional 16 kind of antibacterial agents when compared with carbenicillin.However,after sequencing and analyzing,we found the genes which have mutated do not have known genes related to T4 P.Then we chose dsb A?wbp L?cr C to delete and all of these mutants had the same phenotype with translocation mutants.Combined with literatures,we predicted protein-protein interactions of these gene products and it is reported that dsb A and cr C are associated with Pil A.Therefore,dsb A,wbp L,cr C may be global regulators on the whole genome and they are also potentially associated with T4 P.To sum up,it seems to be not a direct relativity between carbenicillin and twitching after pili-related genes are mutated.Maybe twitching is only one of phenotypes when strains have the sensitivity to antibiotics and the specific mechanism remains to be further studied.What,s more,we also found dsb A,wbp L,cr C may be potential associated with T4 P which adds new members for T4 P gene families and provides excellent clues to explore the mechanism of fimbriae.