Ultrastructural Changes in Clinical and Microbiota Isolates of Klebsiella pneumoniae Carriers of Genes bla_SHV, bla_TEM, bla_CTX-M, or bla_KPC When Subject to β-Lactam Antibiotics

Figure 7

(a–c) Transmission electron micrographs of isolate K21.1-F and K58.1-F of K. pneumoniae. (a) Isolate K21.1-F submitted to 0.5 μg mL⁻¹ ampicillin. Observe irregular formation of septa in a dividing cell (arrow). (b) Isolate K58.1-F subjected to 0.5 μg mL⁻¹ of ampicillin. Cells present electron-lucent (fine arrow), and electron-dense spaces with different sizes and shape throughout the bacterial cytoplasm (arrowheads), in addition to reduction of cytoplasmic contents (star). (c) Isolate K58.1-F subjected to 4 μg mL⁻¹ of amoxicillin. The cells exhibit altered morphologies with cell elongation (large arrow) and undefined forms (asterisk), with the presence of electron-lucent structures with shape and varying sizes scattered throughout the cell cytoplasm (fine arrow). Bars = 0.5 μm.