Bacteria in urine – how dangerous is that?


There are numerous possibilities for bacteria in urine, which can be caused by a lot of urinary tract infections. Unfortunately urinary tract infections are very common and often affect women. There is the possibility of urethritis (inflammation of the urethra), cystitis (inflammation of the bladder) or pyelonephritis (inflammation of the renal pelvis).

Cystitis is a very common disease, especially in women, in which Escherichia coli bacteria accumulate in the tissue of the bladder. Urethritis is similar to cystitis, except that bacteria of the type Neisseria gonorrhoeae (gonococcus) often accumulate directly in the urethra. This infection is also very common.

In the case of inflammation of the renal pelvis, bacteria are also the cause of the disease, in which the connective tissue and the mucous membrane of the renal pelvis are affected. The urine-forming parts of the kidneys, the glomeruli, are not affected by the inflammation. The bacteria are usually the same as in the case of a bladder infection, as this is the cause in many cases.


There is hardly any difference in the symptoms between a bladder infection and a urethritis. In both cases, great pain can often occur. Most of those affected complain of a burning sensation when urinating and some patients also feel itching in the urethra.

In addition, a purulent, cloudy discharge can also be an indication of urethritis. The genital area is also very often reddened. However, it is very noticeable that many women have no symptoms at all, i.e. they do not notice that they suffer from a urinary tract infection.

This can be problematic if the disease is not treated and the bacteria can rise up into the bladder, and the fallopian tubes can become inflamed, which can later even lead to infertility. In addition, the urethra can become narrow and in men the testicles, epididymis and also the prostate can become inflamed. In the case of cystitis, on the other hand, there are considerably more sick women than sick men, and in addition to the symptoms mentioned, there is a strong urge to urinate, which is also present when the bladder is empty.

In severe cases, you can hardly get away from the toilet. In addition, there are always patients who have blood in their urine. Most of the time, however, no additional symptoms occur, so that the affected persons otherwise feel very healthy.

Only very rarely do symptoms like fever occur. However, in the case of inflammation of the renal pelvis, much more severe symptoms such as fever, fatigue, nausea and vomiting can occur. If the urinary tract is infected with bacteria, an inflammation occurs.

This can be very painful. Not only the strength of the pain is decisive for the assessment of the infection. It is also very important where and when the pain occurs.

Typical for a urinary tract infection is the burning pain when urinating. This is a normal reaction of the body to the urinary tract infection. It is often a symptom of an uncomplicated urinary tract infection.

Uncomplicated urinary tract infections usually heal themselves in women. Therefore they rarely require medical treatment. Urinary tract infections can become dangerous if they rise along the ureter and reach the kidneys.

Such an inflammation of the renal pelvis is called pyelonephritis. It should always be treated by a doctor. Otherwise the pathogens can spread with the blood or damage the kidneys.

Pyelonephritis leads to fever and a stronger feeling of illness. Pain in the back or lumbar region is also typical. Tapping the flanks further intensifies this pain.

Colonisation of the urinary tract with bacteria does not always have to trigger a painful inflammation. If bacteria can be detected in the urine without causing pain, this is called asymptomatic bacteriuria. Such asymptomatic bacteriuria can be detected in about 10% of older women.

Normally this does not require treatment. An exception to this is mainly pregnant women. During pregnancy the urinary tract and kidney function change.

Pregnant women are therefore particularly at risk of developing a complicated urinary tract infection. Previous colonisation of the urinary tract with bacteria can further promote this. White blood cells, also called leukocytes, are cells of the immune system.

They serve to defend against disease. In a healthy person, there are less than ten leukocytes per μl urine. In the case of urinary tract infections, this quantity can be greatly exceeded.

The exact origin of the leukocytes can be determined by various tests and microscopically. In the case of the two-lens test, two urine samples are taken one after the other when urinating once. If there are more leukocytes in the first sample than in the second, this is mainly indicative of an infection of the urethra.

If the opposite is the case, the inflammation is probably located in the bladder, the ureters or even the kidney. If the leukocytes come from the kidney, this can be detected microscopically by so-called leukocyte cylinders. There are many reasons for protein in urine.

The urine is produced by filtering the blood through the kidney. If protein passes through the renal filter, most of it is reabsorbed in the kidney. However, even in the case of urinary tract infections, proteins can appear in large quantities in the urine.

These usually do not come from the kidneys. Inflammations in the area of the urinary tract are usually the cause of such an increase in protein in the urine. Some leukocytes, for example, release certain proteins for germ defence.

These get into the urine. A dreaded complication of urinary tract inflammation is the so-called pyelonephritis. It can occur when bacteria rise from the draining urinary tract and attack the kidney.

Symptoms of this are fever, a strong feeling of illness and kidney pain with previous urinary tract infection. Tapping the lumbar region increases the pain. Pyelonephritis is a potentially dangerous disease as it can damage the kidneys. In addition, pathogens can enter the bloodstream and cause sepsis. Therefore, it should always be treated by a doctor.