Abstract
Multidrug-resistant (MDR) bacteria pose a serious threat to global health, which may be addressed using bacteriophage therapy. It is important to measure the susceptibility of bacteria to bacteriophages. We used a micromechanical sensor with a microfluidic channel for rapid antimicrobial susceptibility testing (AST). The interior surface of the microfluidic channel was functionalized with a molecule linker to capture the bacterial cells inside the channel. The Escherichia coli response to the bacteriophage PhiX174 and Staphylococcus aureus response to the bacteriophage Phi44AHJD is observed. The micromechanical sensor measured the mechanical fluctuations induced by nano-movements of the bacteria, reflecting their metabolic activity, before and after viral infection. In other words, the time-dependent oscillations of the microchannel can be correlated to the membrane movement in the cells produced by the cell metabolisms. The initial magnitudes of the fluctuations were different in the two bacteria. Bacteria exposure to the bacteriophages induced a sharp reduction of the sensor response, indicating a marked decrease in bacterial metabolic activities. In contrast to E. coli, S. aureus was resistant to Phi44AHJD, and the significant reduction in its metabolic activity may be attributed to transient dormancy due to stress caused by the viral interaction. This technique provides a rapid and accurate assessment of the susceptibility of bacteria to bacteriophages in a small volume of 150 picolitres.