• Virus An unexpected ally against 'superbugs'

“In any environment, wherever you look.

They are everywhere."

The researcher

Pilar Domingo-Calap

is an expert in capturing phages, those viruses that infect bacteria and can help us

combat resistance to antibiotics


From her laboratory at the Institute for Integrative Systems Biology in Valencia, her team identifies and hunts down these microbes that are even in the most unexpected corners.

“Many times we look in wastewater, because that is an ideal environment to find them, but they have been located in all kinds of places.

For example, one of the phages used in 2019 against an

M. abcessus

infection in an adolescent with cystic fibrosis

was found in an aubergine

," says the researcher, whose team has identified more than 300 useful viruses against


, more of 10 specific phages of

E. coli

, against the genus

Proteus, Citrobacter.


The first phage he found was found in a ditch in the Valencian orchard.



(playing on the initials of its name and the province), experiments showed that it could combat a pathogenic type of



"We take hundreds of samples and in the laboratory we cross them, under biosafety conditions, with pathogenic bacteria that have no treatment," explains the researcher.

In that search, instead of looking in the same environment where the bacteria that you want to eliminate lives,

"sometimes it is best to go blind," he


“What we want is to find viruses that can infect this pathogenic bacterium but that have not been confronted with it before, so that it does not have resistance mechanisms against its action”, he points out.

According to

Aurora Fernández

, a member of the Pharmaceutical Care Group for Infectious Diseases of the Spanish Society of Hospital Pharmacy (SEFH), the WHO has drawn up a list of bacteria that require priority intervention due to the increase in strains with resistance mechanisms and the impact of highly virulent infections.

These include


such as

Enterococcus faecium


Staphylococcus aureus


Klebsiella pneumoniae


Acinetobacter baumannii


Pseudomonas aeruginosa


Enterobacter spp,

which put clinical teams around the world on the ropes every day.

In the hunt for phages that help eliminate these

superbugs , the American researcher

Sabrina Green

is also an expert

, who has found bacteria-attacking viruses in all kinds of environments: from the park closest to her home, where she found phages in feces of dogs and birds, to a poultry farm that provided him with an important find.

“We took samples in each of the cages looking for phages and we found them.

A phage that we found in a fecal mixture of duck and goose

has already been used successfully as a therapy in two cases of E. coli infection

», She assures via email.

As the specialists explain, bacteria can also develop resistance against phages.

In fact, prey and predator usually live in a constant evolutionary war,


new weapons and shields with which to protect themselves and fight.

Precisely to prevent phage therapy from contributing to the generation of new resistance mechanisms, only lytic viruses are sought for treatments, those capable of infecting and causing the bacteria to explode, without their genomes being able to integrate.

But scientists are especially interested in studying the characteristics of this fight between phages and bacteria, where there is an immense field of information to analyze.

"Understanding better the mechanisms of the bacterium to defend itself against phages opens up a world of possibilities, not only from a clinical point of view, but also from others, such as biotechnology," says

María del Mar Tomás

, an expert in phages at the Biomedical Research Institute of A Coruña.

It should not be forgotten, she underlines, that the CRISPR-Cas9 genetic editing tool was developed thanks to the discovery of one of the strategies used by bacteria to defend themselves from the attack of some viruses.

Currently, one of the objectives of this scientific field is to create libraries, catalogs of phages, with detailed information on their genome, their proteome, the location where they were found and, of course, the type of


that is susceptible to their action.

A kind of 'hunting' guide that allows to catch new phages whenever they are needed.

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