Diversity of urine bacteriology practice in Ontario: An external quality assessment

Assessment of urine bacteriology practice in Ontario regarding appropriateness of quantification and the accuracy and Système International d'Unités (SI) conformity in the reporting of results.

A simulated urine specimen with Escherichia coli at a target of 100×10 colony forming units (CFU)/L was submitted to licensed Ontario bacteriology laboratories. Data on the isolation and quantification of the pathogen were required within a stipulated time. Reference values were determined by consensus agreement of the findings of seven designated laboratories.

The challenge was administered to 182 Ontario laboratories licensed to perform urine bacteriological assessment. There was no stratification by type or complexity of facility.

Samples were processed by routine procedures. Date and time of receipt of the sample, date tested, bacterial count, associated quantification units and the method used were the data required. A copy of the report using the laboratory's normal reporting format to user-physicians was requested.

The organism was isolated and correctly identified by 179 laboratories. Only 58% of laboratories reported a count of 100×10(3) CFU/L or more, with 42% reporting a count of between 10 and 100×10(3) CFU/L. The majority used a standard 0.001 mL loop method. Only 87 participants reported using the correct notation of SI units, although a further 65 reported as CFU/L.

The variety of reporting formats is of concern. Processing and reporting should be standardized. Laboratories should provide an explanatory note or interpretation when nomenclature or format of a report is changed.