Bacteriographic examination of urine sediment

Bacteriuria is the detection of bacteria in the urine. Bacteriologic examination of urine yields minimal clinical information for the diagnosis of urinary tract infections, so culture 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 ≥10 ⁵ 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 consider:

• ≥10 ³ microbial bodies in 1 ml of the average urine sample in women with acute uncomplicated cystitis;
• > 10 ⁴ microbial bodies in 1 ml of the middle portion of urine in women with acute uncomplicated pyelonephritis;
• > 10 ⁵ microbial bodies in 1 ml of the average urine sample in women or> 10 ⁴ 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 and pyelonephritis) ;
• any number of bacteria in the urine obtained by suprapubic urinary bladder puncture.

Urine culture with the definition of a bacterial number does not refer to mandatory methods of research 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 the 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 in the urine obtained with the catheter, bacteria in an amount of 10 ⁴ -10 ⁵ cfu / ml.
• In the study of the average portion of urine: the detection of pathogens in the amount of 10 ⁴ cfu / ml in patients with symptoms of urinary tract infection or 10 ⁵ cfu / ml in 2 urine samples taken at intervals of more than 24 hours in children without symptoms of urinary tract infection.
• Significant pyuria; the detection of 10 leukocytes in 1 ml of urine in combination with a bacterial content of 10 ⁵ -10 ⁴ cfu / ml in urine obtained by catheter in children with fever allows a differential diagnosis between infection and contamination.
• Detection of N-acetyl-beta-glucosaminidase in the urine is a marker of damage to the renal tubules; its content also increases with vesicoureteral reflux.

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

Detection of tubercle bacillus 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.

[1], [2]