Eradication of Porphyromonas gingivalis Persisters Through Colloidal Bismuth Subcitrate Synergistically Combined With Metronidazole

Abstract

Microbial persisters enable the development of certain intrinsic strategies for survival with extreme tolerance to multiple antimicrobials. Porphyromonas gingivalis is considered to be the “keystone” periodontopathogen. Indeed, periodontitis, as a highly common inflammatory disease, is the major cause of severe tooth loss and edentulism in adults globally, and yet it is crucially involved in various systemic comorbidities like diabetes. We have recently revealed P. gingivalis persisters-induced perturbation of immuno-inflammatory responses and effective suppression of this key pathogen by bismuth drugs. This study further explored novel approaches to eradicating P. gingivalis persisters through synergistic combination of colloidal bismuth subcitrate (CBS) with traditional antibiotics. P. gingivalis (ATCC 33277) cells in planktonic and biofilm states were cultured to stationary phase, and then treated with metronidazole (100 mg/L), amoxicillin (100 mg/L), CBS, (100 μM) and combinations of these medications, respectively. Persister survival rate was calculated by colony-forming unit. Cell viability and cytotoxicity of CBS were assessed in human gingival epithelial cells (HGECs). Notably, CBS combined with metronidazole enabled the effective eradication of P. gingivalis persisters in planktonic mode, and nearly eliminated their existence in biofilm mode. Importantly, CBS exhibited no effects on the viability of HGECs, along with minimal cytotoxicity (<5%) even at a high concentration (400 μM). This pioneering study shows that P. gingivalis persisters could be well eliminated via the synergistic combination of CBS with metronidazole. Our findings may contribute to developing novel approaches to tackling periodontitis and inflammatory systemic comorbidities.

RNA Sequencing Reveals the Upregulation of FOXO Signaling Pathway in Porphyromonas gingivalis Persister-Treated Human Gingival Epithelial Cells

“…More studies are required to develop novel and precise approaches to tackling microbe-induced inflammatory diseases and systemic comorbidities. Indeed, we have recently demonstrated that bismuth drugs can rescue P. gingivalis -perturbed innate host responses [ 50 ], and P. gingivalis persisters could be effectively eliminated via the synergistic combination of bismuth drugs such as colloidal bismuth subcitrate (CBS) with metronidazole [ 51 ]. Further studies are required to develop new anti-persister drug delivery systems to effectively tackle bacterial persisters and modulate dysregulated immunoinflammatory responses to control P. gingivalis -related diseases.…”

“…In brief, P. gingivalis was cultured in broth for 48 h and re-suspended in fresh broth to an OD600 of 0.1. Subsequently, the bacteria were incubated in the stationary phase (72 h) and further treated with metronidazole (MTZ, Sigma-Aldrich, St. Louis, MO, USA) at 100 mg L −1 for 6 h. It was confirmed by our recent study that about 1% of the P. gingivalis cells remained viable after the 6 h MTZ treatment [ 51 ].…”

Nano-based theranostic approaches for infection control: current status and perspectives

“…19 The ions present in treatment can inhibit protein/ATP synthesis while disrupting the membrane function. Lately, some studies have shown that bismuth exhibits promising antibacterial and antiviral effects on the keystone periodontopathogen Porphyromonas gingivalis 20,21 and SARS-CoV-2. 22 Besides being a promising candidate for antimicrobial agents, metal ions can also reduce the development of AMR and restore the sensitivity of microbes to the antibiotics when coadministered, 18 suggesting that different chemotherapeutic agents applied in combination could greatly enhance the treatment outcomes.…”

Porphyromonas gingivalis Virulence Factors and Clinical Significance in Periodontal Disease and Coronary Artery Diseases

“…In a biofilm, bacteria communicate and have specific tasks [ 106 ]. There are also persistent cells at rest characterized by extreme antimicrobial tolerance [ 107 ]. Based on testing, it has been shown that persistent cells are not mutations but are phenotypic variants [ 102 ].…”