How can we discover new drugs in order to fight pathogenic bacteria?

Monday 27 June 2022


What are bacteria?

Infectious diseases that affect humans are caused by pathogenic microorganisms such as bacteria, viruses, parasites or fungi. These diseases can be transmitted, directly or indirectly, from one person to another.

Today we will talk about bacteria. Bacteria are unicellular microorganisms, not visible to the naked eye and do not have a nucleus, they reproduce by cell division and can have different shapes such as a rod (bacilli), round (cocci), corkscrew-shaped or corkscrew (vibrios), or spiral or helix shaped (spirillum).

Bacteri Escherichia coli

There are some bacteria that do not cause any disease and they are found as normal inhabitants in all living beings (in fact it is estimated that our body contains about 40 trillion bacteria that are equivalent to 1 or 2 kilograms of weight and they are necessary for the proper functioning of our organs) and others that are pathogenic, that is, they cause some type of disease.

Although not all of them are deadly, there are some dangerous bacteria that can be very harmful to the body and cause different damages if they are not detected and treated in time.

The main dangerous and deadly bacteria:

  • Acinetobacter baumannii, causes thousands of deaths a year
  • Pseudomonas aeruginosa, causes severe lung infections or septicemia
  • Campylobacter, which causes campylobacteriosis
  • Salmonella, which causes salmonellosis
  • Escherichia coli, enteropathogen
  • Helicobacter pylori, lives in the stomach and can cause: Septic ulcer, colon irritation...

In a study published by the journal 'The Lancet' (1), it is estimated that drug-resistant bacteria accounted for 1.27 million direct deaths and had some role in at least 4.95 million deaths in 2019, which represents a higher number of deaths compared to those associated with other diseases such as AIDS or malaria. The investigation reflects that AIDS and malaria caused 860,000 and 640,000 deaths respectively in the year under study.

The forecast of deaths in 2050 caused by resistant bacteria is estimated to be about 10 million people worldwide.

How to fight them?

When we have an infection due to bacteria, we take antibiotics, which are drugs (molecules) capable of stopping cell division and therefore stopping the spread of the infection and/or killing the bacteria itself.

Currently the antibiotics we use are broad-spectrum, which means that they are capable of "killing" different types of bacteria, and when one does not work we are prescribed another, also broad-spectrum, which is normally capable of "killing" a different variety of bacteria.

These bacteria evolve and become more resistant to current antibiotics, which is why doctors recommend us not to take antibiotics at the first opportunity.

The WHO estimates that by 2050 antibiotic resistance will be the leading cause of death.

Finding new antibiotics is not easy since the molecular mechanism of action of the latest broad-spectrum antibacterials is 40 years old, despite the enormous efforts made in pharmacy to find new ones.

Heads of national health services, infectious disease professional organizations and infectious disease experts warn that we are witnessing a return to a pre-antibiotic era and bacterial infections (superbugs) are increasing in both severity and frequency, and new drugs are now needed to treat them.

Specific antibiotics for specific pathogenic bacteria represent an innovative approach to developing anti-infective drugs and have the potential to lead to an entirely new generation of antibiotics.

There are various techniques for the creation of new drugs, one of them is through the creation of new molecules (this work is done by biochemists), new specific uses of already known molecules can also be patented, for example Aspirin (Acetylsalicylic acid) now we know that it can also be used as an anticoagulant and another technique that is more laborious is the Screening technique, which we explain below.

What is a screening?

In the same way that in the old days the trementinaires of the Pyrenees went from town to town with their collection of herbs to treat all kinds of diseases, today there are companies that have collections of thousands of natural compounds of which no one has yet been found a therapeutic use.

Thus, on the one hand we have pathogenic (disease-causing) bacteria and on the other hand collections of natural compounds.

Screening consists of testing each of the bacteria that we want to combat against each of the natural compounds in the collection to see what effect it has.

If a collection, for example, has 200,000 compounds and the study includes 20 bacteria, we are talking about 4 million tests that must be carried out with machinery and highly specialized personnel.

The data obtained is voluminous and must also be processed in an automated way to obtain the best candidates to proceed to the next phase of screening.

What characteristics should a good compound have?

In the following phases, we will look for compounds that, just as a triathlete must know how to swim, run and cycle, we will want compounds that are good and balanced in three aspects:

  • Do not allow growth or kill the target bacteria with the lowest possible dose
  • Non-toxic to vital organ tissues
  • They are well tolerated by a small first living being

What is next? Which are the next steps?

From here, any compound that has been discovered still has a long way to go, which can take many years until it reaches our pharmacies.

Before starting trials with humans, the medicine must first pass a series of preliminary safety and tolerance phases in animals.

Once passed, they must pass the 3 phases of a clinical trial, which are studies of new drugs in order to know their tolerance and efficacy, but this is another matter.

For more information on Pharmacological Clinical Trials you can read this article (

As you can deduce, the discovery of a new drug is a very long and laborious process, which goes through many phases to guarantee as much as possible that the remedy is not worse than the disease and that we must be aware that it does not always end with success.

The inLab FIB, of the Polytechnic University of Catalonia · Barcelona Tech-UPC, has collaborated with the company ABAC Therapeutics since 2020 in the development of its own drug discovery platform to identify new antibiotics aimed at combating multi-resistant bacteria called PassNas.


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