Laboratory parameters of the 1st order – obligatory laboratory tests.
- Small blood count [leukocytes (white blood cells) ↑]
- CRP (C-reactive protein) [> 20 mg/l] or PCT (procalcitonin) [> 0.5 ng/ml]
- Urine sediment (urine examination) [leukocyturia (increased excretion of white blood cells in the urine); leukocyte cylinders are evidential of pyelonephritis; nitrite-positive urine status (as an indication of Enterobacteriaceae), bacteriuria (excretion of bacteria with the urine); low proteinuria (excretion of protein with the urine)]Isolated hematuria requires nephrologic workup and follow-up.Caveat (Warning)!
- 13% of children with confirmed urinary tract infection by culture showed no pyuria (pus urine): children with E. coli infections showed no pyuria in only 11%, but if enterococci were the cause, no pus urine formed in 46%.
- In (sub)total obstruction of the urinary tract may not be detectable leukocyturia.
- Urine culture (pathogen detection and resistogram, that is, testing of suitable antibiotics for sensitivity / resistance) from midstream urine possibly catheter urine.
- Serum creatinine [mostly normal].
- Blood culture or blood cultures; cultivation both aerobic and anaerobic – if urosepsis is suspected [positive blood cultures].
Systematic screening for asymptomatic bacteriuria (ABU):
- Nonpregnant premenopausal women (life stage: approximately ten to fifteen years before menopause/very last menstrual period): no (Ia-A).
- Pregnancy: no (Ib-B).
- Postmenopause without other relevant concomitant diseases: no (Ia-A).
- Younger men without other relevant concomitant diseases: no (V-A).
- Diabetic patients without other relevant concomitant diseases with stable metabolic situation: no (Ia-B).
- Patients who are about to undergo urological procedures: yes.
Criteria for microbiologic diagnosis of urinary tract infection or asymptomatic bacteriuria* :
- Urinary tract infection (UTI):
- Pathogen counts > 105 CFU/ml (obtained from “clean” midstream urine).
- Pathogen counts of 103 to 104 CFU/ml may already be clinically relevant in the presence of clinical symptoms (symptomatic patients), provided that they are pure cultures (i.e., only one type of bacteria) of typical uropathogenic bacteria
- Pathogen counts of 102 CFU/ml (at least 10 identical colonies); for urine culture from suprapubic urinary bladder puncture (bladder puncture).
- Asymptomatic bacteriuria (ABU): pathogen counts > 105 CFU/ml of the same pathogen (and same resistance pattern) in two urine samples in the absence of clinical signs of urinary tract infection.
Urine collection (with the aim of reducing contamination/contamination).
- For a study of urine sediment or urine culture: obtaining medium ray; preparatory measures:
- Infants/toddlers:
- “clean-catch” urine, i.e., the infant is held on the lap with genitals exposed and awaits spontaneous micturition. The urine is collected with a sterile container.
- Catheter urine or
- Urine by bladder puncture
- Woman:
- Man:
- Careful cleaning of the glans penis (“glans”) with water.
- Infants/toddlers:
- For an orientational urine examination (e.g., by means of test strips), cleaning of the introitus vaginae (vaginal entrance) or glans penis can be omitted.
Systematic screening for asymptomatic bacteriuria:
- Pregnancy: no (Ib-B).
- Younger men without other relevant concomitant diseases: no (V-A).
- Diabetic patients without other relevant concomitant diseases with stable metabolic situation: no (Ia-B).
- Patients who are about to undergo urological procedures: yes.
Criteria for microbiological diagnosis of urinary tract infection or asymptomatic bacteriuria (ABU)* :
- Urinary tract infection (UTI):
- Pathogen counts > 105 CFU/ml (obtained from “clean” midstream urine).
- Pathogen counts of 103 to 104 CFU/ml may already be clinically relevant in the presence of clinical symptoms (symptomatic patients), provided that they are pure cultures (i.e., only one type of bacteria) of typical uropathogenic bacteria
- Pathogen counts of 102 CFU/ml (min. 10 identical colonies); for urine culture from suprapubic urinary bladder puncture (bladder puncture).
- Asymptomatic bacteriuria (ABU): pathogen counts > 105 CFU/ml of the same pathogen (and same resistance pattern) in two urine samples in the absence of clinical signs of urinary tract infection.
* For a diagnosis of urinary tract infection, significant bacteriuria with monoculture and significant leukocyturia must be present. Note: Screening for asymptomatic bacteriuria should not be performed in nonpregnant women without other relevant comorbidities. Urine collection (with the aim of reducing contamination/impurity).
- For an examination of urine sediment or urine culture: collection of midstream; preparatory measures:
- Infants/toddlers:
- “clean-catch” urine, i.e., the child is held on the lap with genitals exposed and spontaneous micturition (urination) is awaited. The urine is collected with a sterile container.
- Catheter urine or
- Urine by bladder puncture
- Woman:
- Man:
- Careful cleaning of the glans penis (“glans”) of the man with water.
- Infants/toddlers:
- For an orientational urine examination (e.g., by means of test strips), cleaning of the introitus vaginae (vaginal entrance) or glans penis can be omitted.
Thresholds for the diagnosis of different UTI and asymptomatic bacteriuria (ABU).
| Diagnosis | Bacteria detection | Urine collection |
| Acute uncomplicated cystitis in women | 103 CFU/ml | Midstream urine |
| Acute uncomplicated pyelonephritis | 104 CFU/ml | Midstream urine |
| Asymptomatic bacteriuria | 105 CFU/ml |
|
Note: In infants, detection of a urinary tract infection requires: positive findings in urinalysis (leukocyturia and/or bacteriuria) and a count of 105 CFU/mL of a uropathogenic pathogen in a urine specimen obtained by catheter or bladder puncture.
