'Fifteen percent of microbiology reports are wrong!': further experience with an internal quality assessment and audit scheme.

Infection control teams critically depend on the quality of the diagnostic microbiology laboratories with which they are associated. Internal quality assessment (IQA) by specimen resubmission measures the consistency of laboratory performance and can be adapted for medical audit, but few laboratories appear to include these techniques as part of their quality control procedures. We established an IQA scheme in our bacteriology laboratory in May 1989, and the mean discrepancy rate for the first two years was nearly 15%. During the next two years covered by this report, the scheme was extended to include audit of the consistency of medical microbiologists' comments on reports, and a standardized scoring scheme was introduced. Results from the scheme are collated and analysed thrice yearly, and laboratory techniques altered and extra staff training planned to reduce discrepancies. Four thousand four hundred and fourteen specimens (1.4% workload) were resubmitted, and 325 (7.4%) gave discrepant results. During the two years, the overall discrepancy rate fell consistently from 9.4 to 3.2%. Fifty-three discrepancies (1.2%) were in microscopy, and 243 (5.5%) were between culture results. Substantial decreases in technical discrepancies followed training initiatives in sputum bacteriology, and training in anaerobic recognition and improved illumination in the anaerobic cabinet. Problems of consistent recognition of staphylococci and of urine isolates in mixed culture, and of faecal microscopy have proved difficult to eradicate. There was a 20.3% discrepancy rate between medical comments, but only 0.4% would have been likely to result in different patient outcomes. The cost of running the scheme was 4474 pounds per annum, equating to a surcharge of 0.058 pounds to each of our routine diagnostic specimens.(ABSTRACT TRUNCATED AT 250 WORDS)