The phagogram: why this test is essential before any phage therapy

You probably know that feeling of being stuck. After months, even years of antibiotics, the infection is still there. You may have been told: “It’s all in your head” or “You’ll have to learn to live with it”. Yet the pain is very real, and the infection keeps progressing.

If you are now turning to phage therapy, it is to find a solution where chemistry has failed. But be aware: phage therapy is not a “magic medicine” that works blindly. It is high-precision medicine.

For it to work, you cannot simply order phages online as you would buy aspirin. There is a crucial, non-negotiable step that patients often misunderstand: the phagogram.

Why is this test the cornerstone of your potential recovery? Why does it require “fresh” bacteria to be sent to Georgia? Let’s step inside the laboratory.

The end of blind “carpet bombing”: understanding specificity

To understand why the phagogram matters, you first need to grasp the fundamental difference between an antibiotic and a bacteriophage.

Antibiotics often work like an atomic bomb: they wipe out everything in their path, bad bacteria and good ones alike (your microbiota), in the hope that the infection will be eliminated along the way.

Bacteriophages, on the other hand, are elite snipers. They are extremely specific. As explained in leading scientific reviews on the mechanisms of phage therapy, a phage that kills Escherichia coli will pass right by Staphylococcus aureus without touching it. More complex still: a phage that works against strain A of E. coli may be ineffective against strain B of the same bacterium.

This is where the lock and key analogy comes in:

• Your bacterium is a complex, unique lock.
• The phage is a key.
• The phagogram is the moment when hundreds of keys are tried to find the one that opens (and destroys) your lock.

Without this step, trying phage therapy is like trying to open your front door with a key picked at random from a stranger’s key ring. The chances of success are slim.

What exactly is a phagogram?

The phagogram (or phage susceptibility test) is a microbiological analysis carried out in vitro (in the laboratory).

The bacterial “casting”

Once your sample reaches the Eliava Institute in Tbilisi, the technicians isolate your bacterium. They then culture it so that it multiplies and covers the bottom of a Petri dish (a small round dish of gel).

Next, they place different drops on this “bacterial lawn”, containing phage cocktails from their bank (which holds thousands of viral strains collected over a century).

Seeing is believing: the lysis plaque

After an incubation period (usually 24 to 48 hours), the result is visible to the naked eye.

• If the phage does not work: the bacterial lawn stays intact.
• If the phage works: it destroys the bacteria where the drop was placed, creating a visible hole, a clear circle called a “lysis plaque”.

This “hole” is the biological proof that the phage has managed to infect and destroy your specific bacterium [2]. The phagogram report then lists the exact phages (e.g. Intesti Bacteriophage, Pyo Bacteriophage…) that passed the test.

Why must the bacterium be “fresh”?

This is the question patients ask us most often:

“I already have a test from my own laboratory, done 3 months ago, that identifies the bacterium. Why do I need a new sample sent to Georgia?”

The answer lies in two biological facts:

1. Living against living: as explained above, the phagogram is a real fight between two biological entities. The Eliava Institute cannot test its phages on a sheet of paper or a PDF of results. It needs your living bacterium to confront it physically with its viruses [3].
2. Bacterial evolution: bacteria adapt very quickly. The bacterium that infected you 6 months ago may no longer be exactly the same today, especially if you have taken antibiotics in the meantime. It may have mutated, thickened its wall or changed its surface receptors. Using a phage based on an “old” version of your bacterium would be risky and potentially ineffective.

That is why the logistics of shipping your sample are a critical step, which we supervise carefully so that the strain reaches Tbilisi alive.

Ready to take action? Find the practical shipping steps in our dedicated guide: How to send your sample to Georgia, step by step

Medical honesty: the limits of the test

Transparency is a core value for us. It is important to understand what the phagogram tells you, and what it does not.

A positive phagogram (susceptibility proven in the laboratory) is excellent news. It is the essential green light for producing your personalised treatment. It means that a weapon capable of killing your enemy exists.

However, the human body is more complex than a Petri dish. Effectiveness in vivo (in your body) will also depend on:

• How accessible the infection is (can the phage reach the infected site?).
• The presence of complex biofilms (protective shells around the bacteria).
• Your immune system.

That is why the phagogram is a necessary but not sufficient condition for recovery. It is a diagnostic tool that allows the Eliava Institute doctors to design a treatment strategy, but it is never an absolute promise of clinical results [4].

Your journey starts here

Phage therapy is a scientific and human journey. The phagogram is its compass. Without it, we would be navigating blind.

Even before considering a shipment, the first step is purely medical: the Eliava Institute doctors must check whether your condition is eligible for phage therapy. There is no point spending energy and money on a shipment if there is no medical indication.

Do you have a resistant infection?

Don’t stay in doubt. Have your medical situation assessed free of charge by the Eliava Institute doctors to find out whether a phagogram makes sense in your case.

Request my free, confidential assessment

Scientific references

1. Gordillo Altamirano FL, Barr JJ. Phage Therapy in the Postantibiotic Era. Clin Microbiol Rev. 2019;32(2):e00066-18. doi:10.1128/CMR.00066-18. (Level of evidence: major systematic review)
2. Abedon ST. Phage Therapy: Eco-Physiological Pharmacology. Pharmaceuticals (Basel). 2019;12(3):139. (Explains lysis mechanisms and pharmacology)
3. Kakabadze E, et al. Distribution of bacteriophages against common bacterial pathogens in the environment of Georgia. Virus Genes. 2016. (Illustrates the diversity needed in phage banks)
4. Agence nationale de sécurité du médicament (ANSM). CSST Phagothérapie : État des lieux et perspectives. 2019. (Regulatory framework and current limits)
5. Pirie-Diguet K. Phagothérapie : cadre réglementaire et production magistrale. Actualités Pharmaceutiques. 2022.