Examining the Efficacy of Antibiotics and the Proteomic Response in the Treatment of Staphylococcus aureus Biofilms Grown In-Vitro.

Abstract

The proteomic response of Staphylococcus aureus bacteria in a biofilm is examined using MALDI Imaging Mass Spectrometry (IMS) and Liquid-Chromatography Tandem Mass Spectrometry (LC-MS/MS). S. aureus biofilms grown in-vitro and exposed to ampicillin were imaged in order to demonstrate the diffusion pattern of the antibiotic treatment as well as the molecular response of the bacteria. Identification of defensive bacterial proteins resulted in relative quantitation of penicillin-binding proteins (PBPs), cell division proteins, general stress proteins, and methicillin resistance factors across six sections taken from S. aureus biofilm.

Quantitation and identification of said proteins suggest that S. aureus bacteria grown in a biofilm up-regulate methicillin resistance factors and penicillin-binding protein 4 in regions exposed to the drug in an attempt to survive treatment. Cell division proteins as well as penicillin-binding protein 1 are up-regulated in unexposed regions of the film, likely due to cell-to-cell signaling which alerts them to the oncoming drug treatment.