RNA-SEQ-BASED TRANSCRIPTOME ANALYSIS OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS EXPOSED TO LOW-DOSE AMOXICILLIN

Previous studies have shown that low-dose amoxicillin, a cell wall-active β-lactam antibiotic, induces biofilm formation in strains of Methicillin-resistant Staphylococcus aureus. We conducted an RNA-Seq based study to examine the effects of low-dose antibiotics on the gene expression of MRSA with the goal of identifying genes involved in biofilm formation, antibiotic resistance, and the cell wall stress stimulon. We found a number of genes were significantly upregulated or downregulated, many of which have been previously identified to change in expression in response to various antibiotics or be involved in biofilm or cell wall stress. Of particular interest were a hexose-phosphate antiporter gene uhpT which increased in expression 12-fold and phenol-soluble modulin genes psmβ1 and psmβ2 which were downregulated 4.0 and 7.1-fold respectively. Our results highlight a number of genes that warrant further investigation to fully understand their role in antibiotic resistance and the cellular response of MRSA to cell wall-active antibiotics.