The Automicrobic System for urines

Abstract

An evaluation of the Automicrobic System (AMS) for Urines (Vitek Systems, Inc.) was carried out under the auspices of the Product Evaluation Committee of the College of American Pathologists from June 1977 through Oct. 1978. Data generated during this evaluation indicated that, when comparing the AMS methodology to our clinical microbiology laboratory (CML) methodology, a 37% time saving could be realized by utilizing the AMS. Quantitation with the AMS showed a 99% correlation with the CML method except for yeast which correlated only 50% of the time. The average overall identification accuracy was 95%. Negative response accuracy was 99%. Other members of the Enterobacteriaceae which the instrument is not designed to identify may produce erroneous results if they occur in urine specimens [human]. Specimens containing 2 organisms were identified with a 94% correlation when compared to methodology. The time when a well becomes positive may be used as a fairly reliable indicator of significance (count greater than 70,000 colony-forming units/ml) for Escherichia coli, Klebsiella-Enterobacter group and group D enterococcus, but not for Proteus sp., Pseudomonas aeruginosa and yeast. Specimen collection must be performed properly since specimens considered as contaminated by conventional plating-out techniques may be reported out by the AMS as only 1 or 2 organisms and thus lead to an erroneous assumption as to significance. Cost per specimen was more by the AMS method. This is offset by a saving of 1.74 h daily of personnel time and a final report in 13 h. At least 30 urine specimens would be needed daily to pay for the instrument and specimen costs in 1 yr. The AMS can provide significant aid to a CML when all factors are considered.