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By: Andrea Carolina Vargas Malagón, Journalist at UdeA Communications Department 

You don't have to be hospitalized to be exposed to a superbug. Antibiotic-resistant bacteria are not exclusive to hospital settings. We now know they also circulate in water, soil, and animals, and they can even be found in some foods and reach homes. Researchers at Universidad de Antioquia have dedicated years to studying this phenomenon and are working on strategies to contribute to its mitigation from the academic field. This includes using bacteriophages—viruses that infect bacteria—as a therapeutic alternative for infections that no longer respond to traditional antibiotics. 

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Bacteriophages, viruses that infect bacteria, can destroy antibiotic-resistant strains without harming human cells or beneficial microbiota. Photo: courtesy of the MICROBA research group  
 
According to a study published in the medical journal The Lancet —and supported by the World Health Organization— antimicrobial resistance caused 1.27 million deaths in 2019 and was associated with nearly five million more worldwide. If no action is taken, this figure could exceed ten million deaths by 2050. 

“The wide range of good antibiotics we used to have is running out. We have fewer and fewer therapeutic options, and we're reaching the point where there are patients with common infections that were previously easy to treat, but now there are no effective alternatives,” said Judy Natalia Jiménez Quiceno, PhD in Basic Biomedical Sciences. She is also a professor and researcher in the MICROBA research group, attached to UdeA’s School of Microbiology. She is referring to the growing impact of antimicrobial resistance (AMR), a threat that spreads through hospitals, homes, animals, water sources, and natural environments. What was once a phenomenon confined to hospitals is now a public health challenge with serious consequences. 

AMR occurs when microorganisms acquire the ability to tolerate and survive the drugs designed to combat them. Although this occurs naturally as part of their evolution, in the case of bacteria, the overuse or misuse of antibiotics accelerates the process. "Bacteria naturally have the capacity to develop resistance mechanisms, but with the arrival of antibiotics, this evolutionary process accelerated. In other words, antibiotics put more pressure on them, and they quickly develop resistance. They no longer respond to those drugs," explained Jiménez Quiceno. 

Although they are often associated with diseases, most bacteria do not pose a health risk. Many live in the human body and perform essential functions, such as digestion or vitamin synthesis. In the environment, they also participate in fundamental processes. The difference lies in their ability to cause harm: Pathogenic bacteria generate infections, while beneficial bacteria maintain a balance with their environment. The current challenge is the growth of resistant strains that make therapeutic control difficult and are now considered emerging environmental pollutants. 

One of the factors driving the emergence of these strains is the inappropriate use of antimicrobials. These drugs are frequently used outside of clinical settings and under inappropriate management, as occurs in self-medication by the community and in various practices associated with animal production. 

"Antibiotics should be used exclusively to treat bacterial infections, but they are given other uses unjustifiably. For example, they are used as growth promoters or to prevent disease in livestock and farm animals, even when there is no infection, as is the case in aquaculture," explained Jiménez Quiceno. 

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It's not surprising that people with no medical history carry resistant bacteria. This shows that contact with these microorganisms doesn't depend exclusively on exposure to hospital settings but also occurs in everyday life. "Today we see cases of people without obvious risk factors already colonized by resistant bacteria. Self-medication and inappropriate antibiotic use—for example, stopping treatment prematurely or using antibiotics for viral infections—favor the selection of resistant strains and their spread in the community," warned Jiménez Quiceno. 

Because many antibiotics—and bacteria that cause infection—are eliminated from the body through urine and feces, they reach wastewater where they intersect with other pathogenic or environmental bacteria and resistance genes: DNA fragments that encode resistance mechanisms against the action of antimicrobials. This mixture creates an ideal environment for the exchange of genetic material and the selection of more resistant strains. The problem is compounded because, according to Jiménez Quiceno, wastewater treatment plants (WWTPs) are designed to reduce organic load, not to eliminate antibiotics, bacteria, or resistance genes. As a result, many of these bacteria persist at the end of the process and end up in water sources used for animal consumption or crop irrigation. 

Up to 29% of antibiotics ingested by humans end up in rivers and other bodies of water, even after wastewater treatment, according to the study “Global antibiotic contamination in freshwater ecosystems,” published in the scientific journal PNAS Nexus in April 2025. Work  

Work by the MICROBA research group on bacterial resistance to antibiotics in aquatic environments describes the presence of antibiotic-resistant bacteria both at the inlet and outlet of a wastewater treatment plant in the metropolitan area of Medellin. Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae, bacteria commonly associated with hospital- and community-acquired infections. These findings show that wastewater can act as environmental reservoirs that promote the spread of bacteria resistant to beta-lactams, the most widely used family of antibiotics in clinical practice due to their safety and efficacy. Beta-lactams include antibiotics such as penicillin, amoxicillin, and cephalosporins. 

"We are facing a scenario where traditional antibiotics are no longer effective. Therefore, we need to explore new therapeutic alternatives capable of treating infections that currently resist available medications," said Jiménez Quiceno. 

Not all is lost: Bacteriophages as a therapeutic alternative 

Faced with the growing threat of antibiotic resistance, the scientific community has turned to finding solutions that bring hope to the treatment of infections. One of the most promising is the use of bacteriophages, also known as phages, which are viruses that exclusively infect bacteria and, unlike antibiotics, can act with high specificity without affecting the beneficial microbiota of the body or the environment. Furthermore, since they do not attack human cells or alter tissues, they have been considered a safe therapeutic option. 

The MICROBA research group is developing and evaluating this therapeutic alternative at Universidad de Antioquia through the research project "Isolation and characterization of lytic bacteriophages against multi-resistant bacteria of clinical and environmental importance." Professor Judy Natalia Jiménez Quiceno and doctoral student Lorena Salazar Ospina lead the project, through which phages against bacteria such as Escherichia coli, Klebsiella pneumoniae and Saphylococcus aureus were successfully isolated and tested.  Such bacteria, found in the community and wastewater, cause infections in human and veterinary clinical settings. 

"Phages currently represent a great alternative for application in different scenarios where resistant bacteria are present. We have conducted preliminary tests on simulated wastewater in the laboratory and achieved elimination rates of up to 99.9%. We have also tested phages on stainless steel with similar results: 99% removal of bacteria," explained Lorena Salazar Ospina, a microbiologist, bioanalyst, doctoral student in microbiology, and professor at UdeA’s School of Microbiology. 

Phages are not a recent invention, according to Salazar Ospina. For decades, they have been studied as a therapeutic option for both human and animal infections, but the rise of antibiotics has displaced research in this area. However, the increase in resistant bacteria has led science to give phages a new opportunity. 

These viruses act by recognizing and attaching to specific bacteria, injecting their genetic material, and replicating inside them until they destroy them. "The phage enters the bacteria, multiplies within, and eventually breaks it open from within to release new viruses that continue attacking other bacteria. It's a very precise and efficient action," explained researcher Salazar Ospina. 

In some European countries and the United States, their use has been authorized for compassionate therapies for patients without other treatment options. Although they are not widely available yet, their high level of specificity opens the door to personalized strategies. "One of the most promising applications today is targeted therapy: The patient's microorganism is isolated, and if it is determined to be susceptible to the phage, treatment is established," concluded Professor Salazar Ospina. 

Faced with a situation where traditional antibiotics are no longer sufficient, phage research—such as that led by Universidad de Antioquia—represents a window of hope. Its potential lies not only in its effectiveness but also in its ability to adapt to an enemy that is constantly changing and evolving.