The Ontario Association of Medical Laboratories has developed this document to provide practitioners with a guideline for the use of urine culture. The guidelines represent the consensus thinking of a panel of experts in the field. Guidelines are, by their nature, general in focus and cannot apply in every clinical situation. They do not serve as a substitute for sound clinical judgement. These guidelines are appropriate at the time of writing and are applicable in most clinical situations.Semiquantitative urine culture (urine Culture & Sensitivity also referred to as C&S) is the most commonly performed bacteriological test. More than 70% of urine C & S specimens obtained in a community setting, yield no growth or growth of doubtful significance.# Objective:
It is the purpose of this guideline to: - Provide a framework for ordering a urine culture; - Suggest an alternative screening test to avoid unnecessary and costly urine cultures - Review preparation and collection criteria in order to optimize test results.

# Critical Criteria for Selection of Patients for Testing:
Current Canadian and US guidelines do not recommend urine culture as part of screening periodic health examinations of asymptomatic infants, children (1) or the elderly (2).
Some guidelines recommend that urine culture is unnecessary if shortterm therapy has been prescribed for uncomplicated UTI in female patients (3,4).

# Screening for Significant Bacteriuria
When in doubt, chemical urinalysis including leucocyte esterase and nitrite can help to rule out the need for urine culture. This may be carried out in a physician's office providing that the instrument required to read the strip is available. A recent ChedokeMcMaster Hospital study of 1900 inpatient and outpatient urine specimens from patients over 3 years of age confirmed that significant bacteriuria is accompanied by a positive Chemstrip test for one or more of nitrite, leukocyte esterase, or protein in 76% of the urine samples sent for culture (5).
Urinalysis that is negative for nitrite, leucocyte esterase and protein reduces the probability of significant bacteriuria. High glucose concentrations may interfere with the leucocyte esterase assay, therefore, samples with glucose greater than 55 mmol/L should be cultured. Urinalysis will provide a rapid result when the need for urine culture is in doubt. Because the human eye cannot distinguish subtle colour changes reliably, the chemical urinalysis tests (dipstick) must be read by an appropriate instrument (6).
It is NOT appropriate to use urine culture as a screening test in the general population.
It is a reasonable clinical practice NOT to culture urine in women with infrequent episodes of "classical" cystitis in which antibacterials will be administered on clinical grounds. (It should be noted that clinical response to a drug would not necessarily relate to the standard antibiogram because the drug is often concentrated in the urine to more than 50 times its tissue level.)
In the environment of reducing the emergence of multiple resistant organisms, this phenomenon suggests that traditional older drugs such as the penicillins and sulfonamides are usually fully effective.
In cases with less obvious symptomatology such as mild intermittent dysuria, one might choose to screen for the presence of nitrite, protein, or leukocyte esterase in a urinalysis before proceeding to culture.
In all instances, a properly collected specimen, including instruction in cleansing and midstream passage will provide more meaningful and accurate results. Specimens should be immediately stored on ice or refrigerated and sent for analysis as soon as possible. If delays are expected, the use urine stabilizers will reduce the occurrence of erroneous results. Bagged urine specimens from infants are not reliable for urine culture but can be used for urinalysis.
Urine culture and antibiotic susceptibility testing is a costly and timeconsuming procedure. It should be ordered thoughtfully.

# The Ontario Association of Medical Laboratories
The Ontario Association of Medical Laboratories (OAML) represents the communitybased laboratory sector in Ontario.
Its mission is to promote excellence in the provision of laboratory services and, as an essential component of the health care system, to contribute to shaping the future of health care in Ontario.
The OAML encourages the highest level of professional and ethical integrity and technical excellence among laboratory owners, operators and staff in the provision of laboratory services for the benefit of the people of Ontario.

# Guidelines for Clinical Laboratory Practice
The OAML, through its Quality Assurance and Clinical Laboratory Practice Committee, coordinates the development and dissemination, implementation and evaluation of Guidelines for Clinical Laboratory Practice.
A proposed Guideline is developed by a working group of the Committee with the participation of outside experts. The proposed guideline is then submitted to the Committee as a whole and to a Professional Advisory Group who provide an overall review of the document. The comments of the Committee and the Professional Advisory Group are incorporated into a revision of the guideline and this draft is submitted to laboratory Medical Directors, professional associations and other representatives of end users for additional comment. The document is revised in light of these comments and submitted to the OAML Board of Directors for approval.
Approved guidelines are distributed to Community based Laboratories and by them to their client physicians.
There may be additional educational materials produced, if it is thought that they might be useful, and these are distributed with the guideline. The OAML gratefully acknowledges the contributions of the members of the Expert Panel and others who have contributed their expertise, advice and technical support to the development and review of this guideline. This guideline has been reviewed by and comments have been received from representatives of the Laboratory Medicine, Paediatric, Geriatric, Urology, Nephrology, Obstetric, Gynaecology, and General and Family Practice Sections of the Ontario Medical Association and of the Laboratory Proficiency Testing Program of the OMA.