The Relationship between Promoter-Dependent Quorum Sensing Induced Genes and Methicillin Resistance in Clinical Strains of Staphylococcus aureus

Quorum sensing (QS) phenomenon, promoters involved in this pathway and the effect of these promoters on the expression of some structural genes, such as agrA and PII, could reveal the proper activity and gene expression of antibiotic resistance in S. aureus. The aim of this study was defining the relationship between promoter-dependent Quorum Sensing induced genes and methicillin resistance in clinical strains of S. aureus.
In this analytical study, 315 isolates of S. aureus were collected. Resistant and susceptible strains were evaluated for the presence of promoter-dependent quorum sensing induced genes qualitatively and quantitatively. Calculating the gene expression of agrA and PII was carried out by Real-Time PCR. Statistical analysis (descriptive and analytical) was done using SPSS version 16 software and the data analysis of gene expression was carried out by REST 2008 V3.
Among 125 strains of S. aureus resistant to methicillin, 100 isolates (83/33%) had the promoter P2 gene and all isolates had the agrA gene and of 190 strains susceptible to methicillin, 84 isolates (44/21%) had the P2 gene and 169 isolated (88/94%) had the agrA gene. P2 and AgrA gene expression was greater in the resistant isolates in comparison to susceptible isolates.
In accordance with the results of this study, the association between quorum sensing /gene induction and drug resistance is a matter of importance.