Title: Potential Antimicrobial Properties of Coffee Beans and Coffee By-Products Against Drug-Resistant Vibrio cholerae

Authors: Anchalee Rawangkan, Achiraya Siriphap , Atchariya Yosboonruang , Anong Kiddee , Grissana Pook-In, Surasak Saokaew, Orasa Sutheinkul and Acharaporn Duangjai

Journal: Frontiers in Nutrition

Year: 2022

Featured image adapted from an online source and Rawangkan et. al.

In the realm of global health, cholera remains a formidable adversary, capable of triggering widespread outbreaks and claiming lives with alarming speed. The root of this acute diarrheal infection can be traced to the cunning gram-negative bacteria Vibrio cholerae, known to incite cholera pandemics that can prove fatal to individuals within a matter of hours when left untreated. This ancient scourge has left its mark on history, with seven pandemics occurring over the last two decades that have rippled across the world, posing a continuous threat.

The persistence of cholera is disheartening. Despite the existence of a cholera vaccine, over 900,000 cases were reported across 31 countries, leading to over 1,900 deaths in the year 2019 alone. The emergence of drug-resistant strains of Vibrio cholerae compounds the gravity of the issue.

Conventional antibiotics are increasingly losing their efficacy in the face of these resilient bacteria resulting in treatment failures that lead to more severe infections, greater mortality rates, prolonged hospitalization and soaring medical costs. There is an urgent need to come up with strategies to combat these drug-resistant microbes.

However, what if I  tell you a potential answer lies in your morning coffee? Yes, Dear coffee lovers, get ready to be amazed! Your daily cup of coffee might be more than just a morning pick-me-up. In a groundbreaking study by Rawangkan A et. al., scientists have discovered that coffee beans and coffee by-products could become your secret weapon in the fight against this notorious bacterium –Vibrio cholerae. Even more exciting, this discovery might hold the key to combating the drug-resistant strains of this deadly pathogen.

For ages, natural products have been our allies in treating various ailments. In this study, researchers set out to explore the antibacterial powers of coffee beans and coffee by-products against drug-resistant Vibrio cholerae strains. They examined nine different coffee extracts, including various types of coffee beans, coffee pulp, and even coffee leaves. These included light coffee, medium coffee, dark coffee, dried green coffee, dried red coffee, fresh red coffee, Arabica leaf, Robusta leaf, and coffee pulp. Using High Performance Liquid Chromatography (HPLC), the scientists determined the key chemicals (or phytochemicals), present in these extracts chlorogenic acid (CGA), caffeic acid (CA), and caffeine. These extracts were then screened for their antimicrobial activities using an agar well-diffusion technique to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results revealed that all tested strains were indeed sensitive to coffee extracts, with MIC and MBC values in the range of 3.125–25.0 mg/mL and 12.5–50.0 mg/mL, respectively. In other words, the amount of coffee extract needed to stop this pathogen was between 3.125 and 25 milligrams in a milliliter of liquid. That is like needing a tiny drop of coffee in a small cup of water to prevent bacteria growth. To kill the bacteria completely, you needed more coffee, about 12.5 to 50 milligrams in a milliliter of liquid. So, we can say that coffee does not just scare the bacteria away; it also can finish it off.

Dried green coffee, dried red coffee, and coffee pulp were found to be the most effective antibacterials. These extracts were also tested in combination with an antibiotic drug, tetracycline, a commonly used antibiotic to treat bacterial infections. The researchers found that the combined effect on bacterial growth appeared to be greater than the treatment of tetracycline alone, with a fractional inhibitory concentration index (The Fractional Inhibitory Concentration (FIC) Index is a way to measure how two antibiotics work together against bacteria. It tells us if combining two antibiotics makes them more effective, less effective, or if they just work the same as they would alone) ranging from 0.005 to 0.258, which denotes the additive effect.

Now that the researchers established that these coffee extracts were in fact very potent against this pathogenic cholera, the question arose, how exactly do the coffee extracts work? Scanning Electron Microscopy (SEM) revealed the answers, confirming that these extracts disrupt the membrane permeability of bacteria cell walls. The cell membrane is a dynamic structure responsible for controlling the internal conditions necessary for metabolism and energy transfer. It acts as the primary protective barrier separating the cell’s inner environment from the outside surroundings. When this protective barrier is compromised, the normal functioning of bacterial cells comes to a halt which ultimately kills the cell.

This study opens up an exciting new chapter in the fight against drug-resistant Vibrio cholerae. Coffee, it seems, has more to offer than just a caffeine buzz; it might be our new ally in battling a formidable foe. So, the next time you savor your coffee, remember that you might be doing more than just enjoying a warm, flavorful beverage. You could be giving your body a dose of natural antimicrobial protection against a dangerous bacterium. Coffee—it’s more than just a drink; it might hold potential as an ally in the fight against drug-resistant Vibrio cholerae.