Evaluation of Automated Specimen Inoculation for Blood Culture Samples by Use of the Previ Isola(R) System Compared with the Manual Method

ABSTRACT

BACKGROUND: Recently, a new automated inoculating instrument, Previ Isola(R) (bioMerieux, France) was introduced. Although there are many evaluation reports about the inoculation of urine and body fluid samples using Previ Isola(R), no evaluation has been reported for blood samples. The objectives of this study were to evaluate this instrument for the inoculation of blood samples and to compare the microbiological results with the manual loop-to-plate method. METHODS: From March 2014 to July 2014, a total of 296 non-duplicate blood samples showing positive signals on the BacT/Alert 3D system were obtained, and both manual and automated methods were used for sample inoculation. Results of the two methods were compared according to five aspects the culture result, number of single colonies, morphology of colonies, number of re-inoculations, and time required for inoculation. RESULTS: The sensitivity and specificity of Previ Isola(R) were 98.9% and 96.6%, respectively. The positive and negative predictive values were 99.6% and 90.3%, respectively, and the total concordance rate was 98.6%. For Previ Isola(R) and the manual methods, the number of average usable single colonies per plate was 25 and 16, the number of re-inoculations was 60 and 62, and the inoculation time for 15 blood samples was 30 min and 75 min, respectively. The morphology of colonies showed no differences between the two methods. CONCLUSIONS: The automated inoculation instrument, Previ Isola(R), showed relative good concordance with manual method, with high sensitivity and high specificity for blood sample inoculation. Previ Isola(R) may be useful for inoculating specimens including blood samples.