Impact of Chlorophyllin for Antimicrobial Resistance
Updated: Feb 26, 2020
The discovery of antibiotics was undoubtedly one of the greatest contributions to modern medicine. Before their discovery, infectious disease was a leading cause of death. Unfortunately, several factors (such as widespread and improper use of antibiotics, and rapidly evolving bacteria) have strongly contributed to the development and spread of antibiotic resistance. This is especially true for bacteria that are difficult to treat or may even be untreatable with conventional drugs, like multidrug-resistant gram-negative bacteria (MDR gram-negative bacteria).
This study focused on using a combination of Colistin (polymyxin E), a membrane-destabilizing antibiotic, and chlorophyllin against MDR gram-negative bacteria. It can be difficult to treat Gram-negative bacterial infections because of several unique features of these bacteria. For example, “the unique nature of their cell wall makes them resistant to several classes of antibiotics.” These types of infections are typically treated with broad-spectrum antibiotics, however, because these antibiotics have become ineffective against some bacteria, doctors have no choice but to use older drugs, such as Colistin, which can have toxic side effects. (National Institute of Allergy and Infectious Diseases). Colistin is often a “last resort” antibiotic used when all other antibiotics have failed.
In a previous study conducted by the same team, they determined the effect of water-soluble chlorophyllin on Gram-positive and Gram-negative bacteria model strains. They indicated that “antimicrobial treatment with chlorophyll or its derivatives is a promising approach to control bacteria without the use of conventional antibiotics.” However, it was noted that effects of chlorophyllin alone were lower against Gram-negative (E. coli) than against Gram-positive bacteria (Bacillus subtilis, aka hay or grass bacillus).
During the study, sub-toxic concentrations of Colistin were used for a combination treatment with chlorophyllin against Escherichia coli (E. coli) and Salmonella enterica serovar Typhimurium (S. Typhimurium). In the presence of 0.25 µg/mL Colistin, chlorophyllin was able to inactivate both bacteria strains at concentrations of 5–10 mg/L for E. coli and 0.5–1 mg/L for S. Typhimurium.
The data confirmed a combination treatment of chlorophyllin with Colistin “broadens chlorophyllin's application spectrum against Gram-negative bacteria and shows promising evidence that chlorophyllin together with cell membrane-destabilizing substances may become a promising approach in bacteria control.”
Furthermore, this study demonstrated that Colistin can act as a “door opener for other antimicrobial substances such as chlorophyllin, even for the inactivation of mcr-1-positive E. coli cells.” The chlorophyllin and Colistin combination is effective at killing mcr-1-positive E. coli cells, which indicates a potential for a chlorophyllin combination therapy to treat drug-resistant pathogens. However, the photodynamic activity of chlorophyllin influenced the outcome. In this instance, chlorophyllin was not able to inhibit bacterial growth in the absence of light.
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