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 2

(a–h) Transmission electron micrographs of isolate K16R from K. pneumoniae. (a) Untreated bacterial cell—preserved morphology, cytoplasmic membrane (arrow), cell wall (w), and cytoplasm (C) intact. (b) Cell subjected to CTX (64 μg mL⁻¹)—presence of large electron-lucent space due to increased periplasmic space (stars) and reduced cytoplasmic material (C). (c–e) Cells subjected to CAZ (16 μg mL⁻¹). (c-d) Filamentous cells and the presence of membrane compartments containing cytoplasmic material (star). (e) Elongated cell showing loss of cytoplasmic material (star). (f–h) Cell subjected to ATM (4 μg mL⁻¹)—loss of cytoplasmic material (C) and presence of membrane compartments (stars). Bars = 0.5 μm. CAZ: ceftazidime; CTX: cefotaxime; and ATM: aztreonam.