HPLC-MS/MS targeted metabolic profiling reveals distinct metabolic profiles from Staphylococcus aureus small-colony variants.

Staphylococcus aureus is a world-wide health threat due to its prevalence and possible resistance to antibiotic treatment. A variety reasons can contribute to S. aureus antibiotic resistance and one group of phenotypes that may be discovered from S. aureus is named small-colony variants (SCVs). This study focused on applying a HPLC-MS/MS based targeted metabolic profiling approach to detect a set of metabolites that are dysregulated during S. aureus SCVs formation. Over one hundred and eighty metabolites were confidently detected and their difference between S. aureus SCVs and wild type control groups was compared via univariate and multivariate statistical analyses. Twenty metabolites, including 3',5'-cyclic AMP, tyrosine and adenine were identified as SCV specific metabolic features in comparison to the control group. Metabolic profile differences between individually isolated SCV were also observed and compared. Principal component analyses demonstrated clear metabolic profile differentiation between wild type control to SCVs. Metabolic pathway impact analysis also identified multiple metabolic pathways, including alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, that were significantly impacted during SCV formation. To the best of our knowledge, our study is the very first report to detect a large set of altered metabolites induced by S. aureus SCV formation. We believe our method can be used in combination with genomic, transcriptomic and proteomic approaches to achieve a better understanding of the unique physiological and metabolic changes during S. aureus SCV formation, and to assist the potential future development of targeted treatment for S. aureus SCV infections.