How Antibiotics Work In Urinary Tract Infections

It is common for doctors to prescribe antibiotics for urinary tract infections, as antibiotics can cure them. After a medical consultation and a diagnosis confirming bacterial colonization, the professional prescribes antibiotics that the patient must take for several days. Usually that protocol is correct and works.

In fact , urinary tract infections are one of the most common conditions 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 in women. It is estimated (Spanish link) that 20% of the female population will suffer from a urinary tract infection that requires antibiotics at least once in her life.

Although less common in men, chronic prostatitis is a complication that results from not treating it. Many men start with urinary complaints that they don’t pay much attention to. As a result, the colonizing bacteria migrate to the prostate and settle there, causing severe inflammation.

In general, statistics show that lower urinary tract infections are the most common. A lower urinary tract infection occurs in the bladder and urethra, while an upper one is in the kidneys and ureters.

Old age appears to be a risk factor. Postmenopausal women and older men admitted to nursing homes are at high risk of becoming infected.

How antibiotics work for urinary tract infections

Although urinary tract infections in men are less common, they can be the cause of chronic prostatitis. As we mentioned above, bacteria are the microorganisms most associated with urinary tract infections.

They cause more cases than viruses and fungi. Of the bacteria , Escherichia coli causes up to 80% of bladder infections and urethritis.

This bacterium regularly lives in the digestive system, especially in the last part of the intestine. So someone gives it to themselves. In women, it is associated with their shorter urethra and how close their urinary and digestive systems are to each other.

This promotes the passage of Escherichia coli between the anus and the urethral opening, where it moves upwards to colonize. Other microorganisms can cause urinary tract infections to a lesser extent, among which we can mention the following:

• proteus mirabilis
• Klebsiella pneumoniae
• Enterococcus faecalis

All these bacteria are sensitive to a certain type of antibiotic. An antibiogram may therefore be required before starting treatment. This test measures the sensitivity of pathogens to drugs to prescribe the right one that can kill the microorganism.

The most common antibiotics for urinary tract infections

Once the medical professional has identified the causative agent and the antibiogram has determined the most appropriate antibiotic for that urinary tract infection, the treatment protocol begins. No medicine is ideal. Instead, the recipe must be adapted to each specific case.

In this sense, it is important to take into account the patient’s age, possible diseases, allergies and the type of disorder caused in the renal system. What are the most commonly used antibiotics? We explain this in detail below.

Penicillins and derivatives

Being 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. In addition, there are cephalosporins, such as:

• Cephalexin
• Cephalotin
• Ceftriaxone

Most Escherichia coli and Proteus are sensitive to these antibiotics. They are a great option for pregnant women as studies have not recorded any effects on the fetus. So they are quite safe during pregnancy.

Aminoglycosides

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

However, they have many adverse effects that limit their use. They should not be prescribed to pregnant women and infants who are still developing their tissues because of the potential to disrupt cellular formation processes.

Fluoroquinolone

With the passage of time and the discovery of new drugs, a number of new drugs gained ground and became the antibiotics of choice against urinary tract infections. This is the case with fluoroquinolone, which displaced amoxicillin and penicillin.

While this is not always based on scientific evidence, it may have occurred due to the ease of use of these drugs, as they require fewer doses for fewer days. For example, some of the members of this family include:

• Norfloxacin
• Ciprofloxacin (English link)
• pefloxacin
• Gatifloxacin

The first two are the most suitable for this condition because of their bactericidal effect. An advantage of this group is that fluoroquinolone is highly concentrated in the tissues where it is intended to attack.

In men, for example, their ability to penetrate the prostate makes them the first-line treatment to prevent the condition from becoming chronic.  Norfloxacin is found in high concentrations in the urine after ingestion.

co-trimoxazole

This drug 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 often detected in urinary tract infections. If the antibiogram allows it, though, it’s 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 (Spanish link). Its low side effects also give it a safety profile suitable for almost any age and condition.

Safe use of antibiotics in urinary tract infections

A doctor’s choice between one type of antibiotic or the other varies depending on the microorganism causing the infection and its severity.

Regardless of the type of infection, safe use of antibiotics is essential. When taken without a prescription, strains of bacteria become resistant and their treatment becomes increasingly difficult.

It is therefore essential to see a doctor and get an antibiogram if the urgency of the case allows. Thus, the choice of antibiotic is based on evidence of its effectiveness in killing bacteria and reducing the appearance of resistant strains.