PMC

Scanning electron microscopy (SEM) and associated sulfur and bismuth elemental maps of cross-sections of bead 6 and bead 7 showing bismuth distribution. SEM image for bead 6 (A) and bead 7 (D). Associated Sulfur elemental maps for bead 6 (B) and bead 7 (E) and bismuth elemental maps for bead 6 (C) and bead 7 (F). (G) Bar plot of the average percent composition of bismuth in beads 6 and 7, showing a higher average bismuth concentration for bead 6 compared to bead 7. Representative bismuth line scans of single beads with a high and low amount of bismuth, with the correlative bismuth elemental map in the upper right corner for each graph for bead 6 (H, J) and 7 (I, K). For bead 6, the maximum bismuth count/sec was relatively constant within each bead, reflecting a homogenous distribution of bismuth throughout the beads. For bead 7, there was a peak in the bismuth counts/sec at the edge of the beads with otherwise homogeneous distribution of bismuth in the bead interior. Magnified views of the SEM (L) and bismuth element map (M) of the higher density bead 7 (I) showed an irregular bead edge and an accumulation of bismuth grains at the edge consistent with the bismuth peaks in the line graphs at both edges. Note that a slight increase in signal strength is present in the line scans between 20 and 200 μm. This effect is expected as the electron beam travels farther from the specimen edge. The effect is accentuated due to the small diameter of the spheres and may not indicate an actual increase in bismuth.

Structures and structural models of bismuth citrate and bismuth subsubsalicylate (BSS). (a) Dimeric bismuth citrate building block with ball-stick model and polyhedral; (b) the polymeric framework of bismuth citrate linked by three types of bismuth citrate building blocks represented by adjacent green, blue and purple polyhedral respectively; (c) the two-dimensional polymeric structure of the polymeric framework with pyridine rings in the channels (represented as space-filling mode); (d) structural model of rantidine bismuth citrate with ranitidine inserted in the channel; (e) core structure of bismuth subsubsalicylate [Bi₉O₇(HSal)₁₃((CH₃)₂CO)₅] showing the shrouding of the Bi₉O₇ core by 13 salicylate ligands (stick structures) and (f) structure of the Bi₉O₇ core showing the octahedral arrangement of the bismuth atoms (ark brown balls) with seven octahedral faces capped by an oxygen atom (red balls).

Photographs of incubated phage lysis plates. A. Without bismuth. B. With 1.25 mg/ml of bismuth. C. With 5 mg/ml of bismuth. D. With 10 mg/ml of bismuth.

Four bismuth drugs, including bismuth sulfate, bismuth subnitrate, bismuth ammonium citrate, and bismuth triflate, effectively potentiate tigecycline activity against engineered E. coli DH5α [PMD19-tet(X4)]. Dark green regions represent higher cell density. The data represent the average of two biological replicates.