section name header

Introduction ⬇

Urine cultures are most commonly used to diagnose bacterial upper and lower UTIs. Urine is an excellent culture and growth medium for most organisms that infect the urinary tract. The combination of pyuria (pus in the urine) and significant bacteriuria strongly suggests the presence of a UTI.

Procedure ⬆ ⬇

General Collection Procedures for Urine Culture

  1. Early-morning specimens should be obtained whenever possible because bacterial counts are highest at that time.

  2. A clean-voided urine specimen of at least 3–5 mL should be collected into a sterile container. Catheterization and aspiration of a suprapubic or indwelling catheter are alternative methods for procuring urine specimens.

  3. Urine specimens for culture must never be retrieved from a urine collection bag that is part of an indwelling catheter drainage system, except upon initial insertion.

  4. Ideally, urine should be transported to the laboratory and examined as soon as possible. When this is not possible, the urine can be refrigerated for up to 24 hours before being cultured.

  5. Whenever possible, specimens should be obtained before antibiotic or antimicrobial therapy begins.

  6. Professional health personnel should instruct the patient concerning proper specimen collection technique. Failure to isolate a causative organism is frequently the result of faulty cleansing or collection techniques that can come from lack of information about the proper collection procedure.

  7. Provide proper supplies and privacy for cleansing and urine collection. Instruct patients in proper cleansing techniques. The patient who is unable to comply with instructions should be assisted by healthcare personnel.

  8. The urine specimen should be properly labeled. Pertinent information includes:

    1. Patient’s identification information

    2. Healthcare provider’s name

    3. Specific test ordered

    4. Method of collection

    5. Date and time obtained

Clinical Alert

Catheterization heightens the risk for introducing bacteria into the specimen.

Clinical Alert

  1. Urine is an excellent culture medium. At room temperature, it promotes the growth of many organisms. Specimen collection should be as aseptic as possible. Samples should be transported to the laboratory and examined as soon as possible. The specimen must be refrigerated or placed in a preservative if there is a delay in examination.

  2. In the case of suspected urinary tract tuberculosis (TB), three consecutive early-morning specimens should be collected. Special care should be taken when cleaning the external genitalia to reduce the risk for contamination with commensal acid-fast Mycoplasma or Mycobacterium smegmatis.

Procedure for Clean-Catch (Midstream) Urine Specimen

  1. For women:

    1. Wash and dry hands thoroughly.

    2. Remove the cap from the sterile container and place it so that only the outer surface touches whatever it is placed on.

    3. Cleanse the area around the urinary meatus from front to back with an antiseptic wipe or sponge.

    4. Spread the labia apart with one hand. Hold the sterile container in the other hand, using care not to contaminate the inside surface.

    5. Void the first 25 mL into the toilet and then catch the rest of the urine directly into the sterile container without stopping the urine stream until sufficient quantity is collected. Hold the collection cup in such a way that it avoids contact with the legs, vulva, or clothing. Keep fingers away from the rim and inner surface of the container.

    6. Recap the specimen container, taking care not to contaminate the inside surface of the cap.

    7. Wash and dry hands thoroughly.

    8. Observe standard precautions when handling specimens.

  2. For men:

    1. Wash and dry hands thoroughly.

    2. Remove the cap from the sterile container and place it so that only the outer surface touches whatever it is placed on.

    3. Retract the foreskin completely to expose the glans.

    4. Cleanse the area around the meatus with antiseptic wipe or sponge.

    5. Void the first 25 mL of urine directly into the toilet and then void a sufficient amount of urine into the sterile specimen container. Do not collect the last few drops of urine.

    6. Recap the specimen container, taking care not to contaminate the inside surface of the cap.

    7. Wash and dry hands thoroughly.

    8. Observe standard precautions when handling specimens.

  3. For infants and young children:

    1. Use a suitable plastic collection apparatus to collect urine. Because the collection bag touches skin surfaces and picks up commensal organisms, the specimen must be analyzed as soon as possible.

    2. Cleanse and dry the urethral area thoroughly before applying the collection bag.

    3. Cover collection bag with a diaper or undergarment to prevent dislodging.

    4. Be aware that specimens collected by catheterization may be necessary to detect a UTI because of the contamination associated with collection bags.

Clinical Implications ⬆ ⬇

  1. A bacterial count of more than 100,000 colony-forming units (CFU)/mL indicates infection. A mixed bacterial count of less than 10,000 CFU/mL does not necessarily indicate infection but rather indicates possible contamination. However, growth of a single potential pathogen to more than 10,000 CFU/mL may be clinically significant in a symptomatic patient.

  2. The following organisms, when present in the urine in sufficient quantity, may be considered pathogenic:

    1. Escherichia coli and other Enterobacteriaceae

    2. Enterococcus spp.

    3. Neisseria gonorrhoeae

    4. M. tuberculosis (requires special culture media)

    5. P. aeruginosa

    6. S. aureus

    7. Staphylococcus saprophyticus

    8. Streptococci (beta-hemolytic, usually group B)

    9. C. albicans and other yeasts

  3. Urine samples obtained by straight catheterization, suprapubic aspiration, or cystoscopy or during surgery represent bladder urine. Growth of any isolate is considered clinically significant.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain purpose of test, procedure for urine collection, and interfering factors.

  2. Ensure that the cleansing procedure is done correctly to remove contaminating organisms from the vulva, urethral meatus, and perineal area so that any bacteria found in the urine can be assumed to have come only from the bladder and urethra.

  3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Clinical Alert

The urine culture sample should not be taken from a urinal or bedpan and should not be brought from home. The urine should be collected directly into the sterile container that will be used for culture.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor for signs of UTI. Counsel the patient appropriately about treatment and possible further testing.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆ ⬇

  1. Patients who are receiving forced fluids may have urine that is sufficiently dilute to reduce the bacterial count to less than 100,000 CFU/mL.

  2. Bacterial contamination comes from sources such as:

    1. Perineal hair

    2. Bacteria beneath the prepuce in male patients

    3. Bacteria from vaginal secretions, from the vulva, or from the distal urethra in female patients

    4. Bacteria from the hands, skin, or clothing

Reference Values ⬆

Normal

Negative