Bacteriographic examination of urine sediment

Bacteriuria is the detection of bacteria in the urine. Bacteriologic examination of urine provides minimal clinical information for the diagnosis of urinary tract infections, therefore, cultural methods are used. The latter allow not only to establish the type of pathogen, but also to determine the bacterial number( the number of pathogens in 1 ml of urine).Asymptomatic bacteriuria is considered the detection of> 105 microbial bodies of the same microorganism in 1 ml of urine in 2 consecutive analyzes performed at intervals of more than 24 hours. Clinically significant bacteriuria according to the "Recommendations of the European Association of Urologists for the Treatment of Urinary Tract Infections and Reproductive System Infections in Men"In adults they consider:

■> 103 microbial bodies in 1 ml of the average urine sample in women with acute uncomplicated cystitis;

■> 104 microbial bodies in 1 ml of medium urine in women with acute uncomplicated pyelonephritis;

■> 105 microbial bodies in 1 ml of the average urine sample in women or> 104 microbial bodies in 1 ml of the average urine sample in men( or in urine obtained with a catheter in women) with a complicated urinary tract infection( acute cystitis andpyelonephritis);

■ any number of bacteria in the urine obtained by suprapubic urinary bladder puncture.

Urine culture with bacterial number determination is not a mandatory method of investigation in women with uncomplicated cystitis. It is shown together with the definition of the sensitivity of the isolated pathogens to antibacterial drugs with the preservation of the symptoms of cystitis or their relapse within 2 weeks. Urine culture should be performed in patients with acute pyelonephritis.

Bacteriological diagnosis of urinary tract infections in pregnant women has its own characteristics. In most women, bacteriuria occurs before pregnancy. In 20-40% of women with asymptomatic bacteriuria during pregnancy develops acute pyelonephritis. The frequency of false positive results of a single culture examination of the average portion of urine can reach 40%.In this regard, all women with a positive bacteriological test should be re-sowed urine after 1-2 weeks, paying special attention to the toilet of the external genitals before urinating. After the treatment is completed, the culture of the urine is carried out 1-4 weeks later, and again before the birth.

In children, a diagnosis of urinary tract infection is established based on the following criteria.

■ When sowing urine from the urine receiver, only a negative result is considered significant.

■ Detection of any number of bacteria in the urine obtained by suprapubic urinary bladder puncture.

■ Detection of coagulase-negative staphylococci in the urine in an amount of> 300 cfu / ml.

■ Detection of bacteria in the urine obtained with a catheter in the amount of 104-105 cfu / ml.

■ In the study of the average urine sample: the detection of pathogens in the amount of 104 cfu / ml in patients with symptoms of a urinary tract infection or 105 cfu / ml in 2 urine samples taken at intervals of more than 24 hours in children without symptoms of a urinary tract infection.

■ Significant pyuria;the detection of 10 leukocytes in 1 ml of urine in combination with the content of bacteria 105-104 cfu / ml in urine, obtained with a catheter, in children with fever allows a differential diagnosis between infection and contamination.

■ Detection of N-acetyl-b-glucosaminidase in urine - a marker of damage to the renal tubules;its content also increases with vesicoureteral reflux.

To detect the tuberculosis in the urine of mycobacteria, a bacterioscopic examination is carried out with the coloring of the smears from the Zill-Nielsen sediment.

Detection of tubercle bacilli in the urine is the most reliable sign of kidney tuberculosis. With the exclusion of prostatic tuberculosis in men, the detection of tubercle bacilli in the urine should be regarded as an indication of the presence in the kidney of even the smallest, "subclinical" foci of tuberculosis. If a tuberculosis process is suspected in the kidneys, but with a negative bacterioscopic examination, a bacteriological study of the urine is necessary - its triple sowing on the mycobacterium tuberculosis.