Бак посев отделяемого из уретрального канала на инфекции мочевых путей (OYRON WELL D-ONE)

Laboratory screening for urinary tract and kidney infections (UTI screen) supports the initial evaluation of infectious inflammation involving the urethra, bladder, ureter, and renal parenchyma (urethritis, cystitis, ureteritis, pyelonephritis). The assessment typically combines urinalysis, urine sediment microscopy, nitrite testing, and urine culture to detect pyuria and bacteriuria, verify the causative organism, and inform antimicrobial selection. When urine is collected as two sequential portions, results may help suggest lower versus upper tract involvement. This screening approach is also applicable for asymptomatic individuals in whom a smoldering or chronic infection is suspected or following urologic instrumentation.

The kidneys and urinary tract constitute the excretory system, which maintains homeostasis and produces urine. Renal functions include excretion, regulation of water–electrolyte balance and acid–base status, endocrine activity, and control of blood pressure and erythropoiesis. The urinary tract comprises the calyces, renal pelvis, ureters, bladder, and urethra. For early evaluation of infection, urinalysis, microscopy of the urine sediment, and urine culture are used together. Collecting two sequential portions can provide clues to anatomic localization: abnormalities confined to the first portion favor involvement of the distal urethra (urethritis), whereas shifts seen in the second portion suggest pathology in the proximal urethra or bladder (urethritis or cystitis); in men, second‑portion abnormalities are characteristic of inflammation of the prostate or seminal vesicles. Laboratory patterns can also point toward ureteral or renal disease (ureteritis, pyelonephritis). Cloudy or whitish urine or a visible white sediment may reflect leukocytes, bacteria, or yeasts. An alkaline urinary pH (7.0–9.0) is associated with urinary tract infection because many organisms hydrolyze urea. Leukocyturia indicates inflammation; when marked, pyuria yields turbid urine and leukocytes in all microscopic fields. Hematuria may accompany infection and is reported in about one‑third of pyelonephritis cases. Leukocytic and granular casts in the sediment support acute pyelonephritis, exacerbation of chronic pyelonephritis, or renal abscess. Nitrite positivity in urine supports bacterial infection of the urinary tract. In healthy individuals, the system is sterile; scant flora from the distal urethra typically remains below 1×10^4/mL and does not reduce urinary nitrates, so nitrite tests are negative. Bacteriuria is conventionally defined as ≥1×10^5 bacteria/mL. Gram‑negative rods predominate (including Escherichia coli, Klebsiella, Proteus, Enterobacter, Salmonella, Pseudomonas, Citrobacter), with staphylococci, streptococci, and enterococci also encountered; ascending infection often leads to pyelonephritis. The condition is common in women and older men; bacteriuria in pregnancy occurs approximately fivefold more often than in nonpregnant women, and Escherichia coli accounts for about 70% of pyelonephritis in pregnancy. Glucosuria facilitates ascending infection. Risk increases with urethritis, cystitis, pyelocystitis, ureteritis, urolithiasis, and after urologic procedures; Candida species may also be involved. Midstream collection of the first morning urine after meticulous cleansing of the external genitalia using a sterile container reduces false‑positive results. Organisms such as gonococci, streptococci, and Mycobacterium tuberculosis do not generate nitrites, yielding negative nitrite tests despite infection; infants’ urine lacks nitrites as well. In these settings, bacteriologic culture is recommended to confirm infection. Chronic pyelonephritis may be clinically silent in 30%–40% of cases, underscoring the value of laboratory screening in at‑risk populations.