Fig. 1.

Cell morphology of the MDR Bp1651 strain cultured in the presence and absence of β-lactam antibiotics (AMC, CAZ, and IPM) (a). Optical screen images were captured during exponential and stationary phase growth. Drug concentrations (μg/ml) corresponding to the CLSI breakpoint for susceptibility (dotted green squares) and three or four successive two-fold increasing concentrations. Blue squares represent the Bp1651 MICs and the blue line indicates the CAZ MIC is ≥128 μg/ml. Distribution of cell lengths of Bp1651 cultured in the presence and absence of CAZ (μg/ml) (b). Histograms represent cells (n = 100) measured (μm) after 4 h using the thinned length object feature. Multidrug-resistant (MDR), amoxicillin-clavulanic acid (AMC), ceftazidime (CAZ), and imipenem (IPM)