title: External quality assessment for clinical microbiological laboratories in Norway 1982. 1. Evaluation of the identifications of 24 bacterial strains.
abstract: The first general external quality assessment (EQA) for clinical microbiological laboratories in Norway was carried out in 1982. Fifteen of 16 county and regional laboratories participated. Twenty-four pure cultures of different bacterial species were distributed by post. The distribution was "open" in the sense that the participants were aware of the cultures being part of the assessment. The strains had to be treated as routine clinical specimens. The bacterial identifications, the identification methods and the antibiotic sensitivity pattern had to be reported. The mean number of erroneous identifications was 2.7 (11.3%). Eleven strains were correctly identified by all laboratories, whereas four strains were misidentified by four to seven laboratories, accounting for approximately 50% of all misidentifications. All laboratories used "rapid" biochemical methods when identifying Gram-negative rods, mainly the "Three-tube method" and API 20E. Five laboratories used only one method, 10 used a combination of two or three methods. The use of more than one method did not give any substantial advantage. The accuracy of the "rapid" biochemical methods was approximately 88%, contrasting to approximately 96-98% when scientifically evaluated. The necessity of developing a permanent EQA scheme for microbiological laboratories is emphasized and a possible design for this is discussed.
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D005069:Evaluation Studies as Topic; D009664:Norway