How Antibiotics For Urinary Tract Infections Work

Antibiotics are used to treat urinary tract infections because the causative agents are usually bacteria. We will tell you about the different therapeutic options in this article.
This is how antibiotics against urinary tract infections work

It is common for doctors to prescribe antibiotics for urinary tract infections, as antibiotics work to cure them. After a medical consultation and diagnosis that confirms bacterial colonization, the doctor prescribes antibiotics the patient must take for a few days. In most cases, that protocol is correct and works.

In fact, UTI is one of the most common ailments in general outpatient practice around the world. That said, antibiotics have historically been the most effective way to control this condition and prevent complications.

Urinary tract infection

This condition is very common, especially among women. It is estimated that 20% of the female population will suffer from a urinary tract infection that requires antibiotics at least once in a lifetime.

Although less common in men, chronic prostatitis is a complication due to lack of treatment. Many men start with urinary tract symptoms that they do not pay much attention to. Consequently, the colonizing bacteria migrate to the prostate and settle there, causing severe inflammation.

Overall, statistics show that lower urinary tract infections are the most common. An infection of the lower urinary tract occurs in the bladder and urethra, while the upper one in the kidneys and ureters.

In addition , aging appears to be a risk factor. Menopausal women and older men admitted to nursing homes are highly likely to become infected.

A man with a UTI
Although urinary tract infections are less common in men, they can be the trigger for chronic prostatitis.

This is how antibiotics against urinary tract infections work

As we mentioned above, bacteria are the microorganisms that are most related to urinary tract infections. They cause more cases than viruses and fungi.

Among bacteria, Escherichia coli causes up to 80% of cases of cystitis and urethritis. This bacterium lives in the digestive system, especially in the last part of the intestine. Therefore, the same person transmits it to himself.

In women, it is associated with shorter urethra and how dense the urinary and digestive systems are. This favors the transfer of Escherichia coli between the anus and the urethral opening, where it rises to colonize.

To a lesser extent, other microorganisms can cause urinary tract infections, including the following:

  • Proteus mirabilis
  • Klebsiella pneumoniae
  • Enterococcus faecalis

All of these bacteria are sensitive to some types of antibiotics. Therefore , it may be necessary to use an antibiogram before starting treatment. This test measures the pathogen sensitivity of drugs to prescribe the correct one that is capable of killing the microorganism.

The most common types of antibiotics for urinary tract infections

Once the doctor has identified the causative bacterium and the antibiogram has determined the most appropriate antibiotic for that urinary tract infection, the treatment protocol begins. No medication is ideal. Instead, the recipe must be adapted to each individual case.

In this sense, it is important to take into account the patient’s age, possible diseases, allergies and the type of disorder in the kidney system.

So what are the most commonly used types of antibiotics?

Below we explain this in detail.

Penicillins and derivatives

As it is one of the oldest groups in the fight against bacteria, penicillins have evolved. Amoxicillin and ampicillin belong to this family and are effective against many different microorganisms. Similarly, there are cephalosporins, such as cephalexin, cephalothin and ceftriaxone.

Most Escherichia coli and Proteus are sensitive to these types of antibiotics. They are a great option for pregnant women since studies have not registered effects on the fetus. Thus, they are quite safe during pregnancy.

Different types of antibiotics
Penicillin and its derivatives are the most commonly used drugs in cases of bacterial urinary tract infections.


This family, whose representative is gentamicin, can fight gram-negative bacteria. This means that they do not stop bacterial growth, but rather kill gram-negative microorganisms. For this reason , doctors prescribe them for enterococci.

However, they have many side effects that limit their use. They should not be prescribed to pregnant women and infants who are still developing tissues due to the possibility of disrupting cell formation processes.


As time went on and new medications were discovered, some new medications gained a foothold and became the preferred antibiotic types for urinary tract infections. This is the case with quinolones that displaced amoxicillin and penicillin.

Although this has not always been based on scientific evidence, it may have been due to the ease of use of these medicines, as they require fewer doses for fewer days.

A few of the members of this family are norfloxacin, ciprofloxacin, pefloxacin and gatifloxacin. The first two are the most prescribed for this condition due to their bactericidal effect. An advantage of this group is that quinolones are highly concentrated in the tissue where they must attack.

For example, their strength allows them to penetrate the prostate for first-line treatment to prevent the condition from becoming more chronic in men. Meanwhile , norfloxacin is found in high concentrations in the urine when ingested.


This medication combination is considered an antibiotic on its own. However, it cannot always be used because its ability to act is limited to the bacteria most commonly detected in urinary tract infections. Still, if the antibiogram allows it, it is not a bad option.

This drug has a good effect on the prostate, which is why it is the second choice for men after norfloxacin. In addition, the low side effects provide a safety profile suitable for almost all ages and conditions.

A person taking antibiotics for urinary tract infections
A doctor’s choice between one type of antibiotic or another varies depending on the microorganism causing the infection and its severity.

Safe use of antibiotics for urinary tract infections

No matter what type of infection it is, safe use of antibiotics is important. When taken and prescribed arbitrarily, bacterial strains become resistant and treatment becomes increasingly difficult.

It is therefore important to consult a doctor and get an antibiogram if the case’s urgency allows it. Thus, the choice of antibiotics is based on evidence of its effectiveness in killing bacteria and reducing the incidence of resistant strains.

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