Bacteriuria (ICD-10-GM R82.7: Abnormal findings on microbiological urinalysis) is the excretion of bacteria in urine.
Significant bacteriuria is defined as a pathogen count of 105 germs per ml urine (CFU/ml). Detection is by urine culture. A positive urine culture is followed by a resistogram, i.e. testing of suitable antibiotics for sensitivity/resistance (see below “Urine testing for pathogens”).
Criteria for microbiologic diagnosis of asymptomatic bacteriuria (presence of bacteria in urine) or urinary tract infection (UTI):
- Asymptomatic bacteriuria (ABU; ASB): pathogen counts > 105 CFU/mL of the same pathogen (and same resistance pattern) in two urine specimens in the absence of clinical signs of UTI.
- 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).
In infants
- For the detection of a urinary tract infection is required: positive findings in urinalysis (leukocyturia and/or bacteriuria) and in a urine sample obtained by catheter or bladder puncture a number of > 105 CFU/ml of a uropathogenic pathogen.
In pregnancy
- Screening by urinalysis, including culture, should preferably be performed at the end of the first trimester (third trimester of pregnancy), as therapy for asymptomatic bacteriuria is recommended during pregnancy.
Patients who are about to undergo urological procedures.
- Screening for and treatment of asymptomatic bacteriuria is indicated.
Asymptomatic bacteriuria is most commonly seen in women up to 60 years of age, the elderly, and patients with diabetes mellitus.
Bacteriuria can be a symptom of many diseases (see “Differential diagnoses” below).
The prevalence (disease incidence) is 1-2% for preschool-aged girls and 6-10% for older women. In pregnant women, the prevalence of asymptomatic bacteriuria is in the range of 2-10%.In men, asymptomatic bacteriuria is very rare.Asymptomatic bacteriuria in long-term catheters is up to 100%. In intermittent catheterization, it is up to 50%.
Course and prognosis: Bacteriuria always requires medical clarification. Symptomatic bacteriuria always requires antibiotic therapy. Urinary tract infections in men also require differentiated clarification. Asymptomatic bacteriuria does not require treatment in non-pregnant adults. This also applies to healthy children regardless of age. Children under 4 years of age with recurrent urinary tract infections and known vesicoureteral reflux (backflow of urine from the bladder via the ureters into the renal pelvis) are treated even in the case of asymptomatic bacteriuria.Asymptomatic bacteriuria in pregnant women (see above) should always be treated, since in such cases the risk of pyelonephritis (inflammation of the renal pelvis) is increased by about 30%.
For detailed information on diagnosis and therapy as well as course and prognosis, see cystitis or pyelonephritis.
