Evaluation of an Automated Instrument for Inoculating and Spreading Samples onto Agar Plates

The findings from a preliminary assessment of a new instrument designed for the inoculation and spreading of specimens for microbiological analysis onto agar plates are described. The study found that the instrument was able to select full or biplates from a number of input cassettes, each containing different agar types. Samples were then inoculated by the instrument onto the agar surfaces and spread by a novel plastic applicator. Following this, the instrument labeled the plates and sorted them into a number of specified output stations. It was found that the instrument was able to inoculate and spread samples over a greater proportion of the agar plate surface than the manual loop-to-plate method. As a consequence, up to 44% more usable colonies were produced per plate from clinical specimens and standard cultures. Viable counts showed that the instrument was able to detect as few as 10(2) CFU/ml in fluids and also facilitated the enumeration of organisms, particularly in specimens such as urine.