Changes in Urine Culture Result Reporting
Tuesday, May 15, 2018
In order to more closely comply with guidelines recommended by the American Society of Microbiology and the Infectious Disease Society of America, the Microbiology department at Laboratory Alliance of Central New York has implemented changes in the reporting of quantitative results for clean-catch, mid-stream urine specimens.
Quantitative urine culture results will now be reported as: less than 10,000 bacteria/ml; 10,000 to 100,000 bacteria/ml; or, greater than 100,000 bacteria/ml.
For mid-stream specimens, a result of “less than 10,000 bacteria/ml” is regarded as insignificant bacteriuria generally due to urethral contamination during specimen collection, while a quantitative result of “greater than 100,000 bacteria/ml” typically represents significant bacteriuria supporting the diagnosis of a lower urinary tract infection.
Colony counts of “10,000 to 100,000 bacteria/ml” are considered indeterminate or equivocal results in which the diagnosis of infection cannot always be supported by the quantitative urine culture result alone. In such cases, clinical judgment and/or other laboratory tests may be needed to establish the diagnosis. In symptomatic patients with pyuria, the results may be significant. Alternatively, a repeat urine specimen might be indicated, paying strict attention to proper specimen collection technique and urine transport conditions.
It is important to emphasize that bacterial identifications and antimicrobial susceptibility testing (when appropriate) will be performed on up to two organisms for any urine specimen that has a colony count of greater than 10,000 bacteria/ml.
Healthcare providers are reminded that urine colony counts are adversely affected by improper collection and/or specimen delays in transport to the laboratory. Strict adherence to proper urine collection and transport procedures as recommended by the Microbiology laboratory will result in a more reliable test result and urine colony count. In addition, the time of specimen collection (first morning urine is best), the patient’s state of hydration, and other patient factors can adversely affect the quantitative urine culture result.