Urinary tract infections (UTIs) are among the most common bacterial infections worldwide, affecting millions of people annually. They are most common among women, the elderly, and patients with catheters or chronic medical conditions.

The main pathogens responsible for UTIs are:

• Escherichia coli (E. coli) is the most common pathogen, causing over 70% of all cases. This bacterium can adhere to the bladder epithelium, forming colonies and biofilms.

• Klebsiella pneumoniae is the second most common pathogen, especially among hospitalized patients. It often demonstrates resistance to beta-lactam antibiotics.

• Proteus mirabilis is capable of forming kidney stones due to urease, which changes the pH of urine.

• Enterococcus faecalis is particularly common in hospitals and is often found in patients with long-term use of catheters.

• Pseudomonas aeruginosa is an opportunistic pathogenic bacterium that causes complicated infections and is resistant to many antibiotics.

How pathogens enter the urinary system

In most cases, bacteria enter the bladder ascending through the urethra. This is especially common in women due to the shorter length of the urethra. Infections can also occur due to:

• use of catheters;

• poor hygiene;

• anatomical anomalies;

• diabetes mellitus and other immunodeficiency conditions.

Symptoms and complications caused by UTIs

Classic symptoms of a UTI include:

• frequent and painful urination;

• burning sensation;

• cloudy or foul-smelling urine;

• pain in the lower abdomen or back;

• sometimes an increase in temperature.

If the process becomes complicated, pyelonephritis may develop, accompanied by high fever, nausea, pain, and even sepsis in severe cases.

The problem of antibiotic resistance in pathogens causing UTIs

Antibiotic resistance poses the greatest threat to the treatment of urinary tract infections. Many common pathogens, including E. coli, Klebsiella, and Pseudomonas, have acquired the ability to produce beta-lactamases, carbapenemases, and other enzymes that neutralize the effects of medications.

As a result, traditional treatments are often ineffective. Patients are forced to undergo lengthy courses of therapy, which increases resistance and side effects.

Bacteriophages as a new tool in the fight against UTIs

In this context, phage therapy—the use of bacteriophages, viruses that specifically target bacterial cells—comes to the forefront. These "bacteria hunters" are able to accurately recognize pathogens without affecting beneficial microflora.

Advantages of phages:

• selectivity for a specific type of bacteria;

• ability to penetrate biofilms;

• absence of toxic effect;

• low risk of developing resistance with the correct selection of phage;

• Possibility of use in the form of suppositories, instillations, capsules.

Examples of phage therapy research in urology

1. Phages against E. coli: clinical experience.
   In 2020, a study was conducted in Poland involving patients with recurrent bladder infections. They were administered a phage cocktail intraurethrally for three weeks. Clinical improvement was achieved in 70% of cases without the use of antibiotics.

2. Bacteriophages against Klebsiella pneumoniae.
   In the US, researchers have developed phage cocktails targeting Klebsiella. In one case, a patient with a chronic infection resistant to all available antibiotics was successfully treated with a tailored bacteriophage.

3. Experimental model of pyelonephritis in animals.
   Scientists in France used a mouse model to test phages against Pseudomonas aeruginosa. After intravenous and intraurethral administration, bacterial levels in kidney tissue decreased tenfold. This demonstrated the potential of phages in treating UTI complications.

4. Phage therapy in combination with antibiotics against UTI.
   In 2019, French researchers studied the use of bacteriophages to treat Escherichia coli infections. The results showed that phages, when used in conjunction with antibiotics, significantly reduced the development of resistant bacteria, reducing the symptoms of the infection.

5. Phage therapy against infections caused by Pseudomonas aeruginosa.
   In 2020, American scientists tested bacteriophages against Pseudomonas aeruginosa, which causes severe UTIs, especially in patients with catheters. The study showed that the phages were effective in killing antibiotic-resistant strains.

6. Phage therapy against chronic UTIs in women.
   A 2021 study conducted in the UK showed that phages can effectively treat chronic infections caused by antibiotic-resistant E. coli. This approach has fewer side effects than traditional treatment.

7. Predicting the effectiveness of phage therapy against UTIs.
   In 2024, a study confirmed that the correct choice of bacteriophage cocktail for the treatment of E. coli infections can significantly improve the effectiveness of therapy and reduce the risk of developing phage resistance.

8. Phage therapy against recurrent cystitis.
   In 2025, a study was conducted evaluating the effectiveness of phage therapy in women with recurrent cystitis caused by multidrug-resistant bacteria. The results showed that phages may be an effective alternative to traditional antibiotics in such cases.

Urinary tract infections pose a serious healthcare challenge, especially given the growing resistance of bacteria to antimicrobials. Traditional approaches are often ineffective, and the number of complicated cases is constantly increasing.

In this context, bacteriophages acquire particular value. Their potential as an alternative or complement to antibiotic therapy has already been demonstrated in a number of clinical and laboratory studies. The next step should be the inclusion of phage therapy in standard medical practice.