Present antimicrobial susceptibility testing technologies generate data at a single time point over 24 hours of a day, which are considered to represent the susceptibility profile of the antibiotic in question. By questioning the epistemological value of the single time-point susceptibility testing, a time-dependent antimicrobial susceptibility study was designed. Time-dependent antimicrobial susceptibility testing was realized at six different hours of the same day to reveal the time-dependent variation of in vitro interaction between antibiotics and bacterium. The study data revealed a significant daily time-dependent oscillation in antimicrobial susceptibility testing in terms of inhibition zone value. The bacterium seems to be most susceptible to antibiotics in the dark phase (or transition to the dark phase) of the day.