Automated Reading of Urine Cultures Using a Novel Image Analysis Device

9 April 2015

In recent years, the application of image analysis technologies within the clinical laboratory, particularly in the cell-based fields of haematology, anatomical pathology and cytopathology, has increased. In the microbiology laboratory, the agar plate remains an important diagnostic tool and alternate technologies have not yet provided a comprehensive replacement. This is despite the reality that agar plates require numbers of highly trained staff, time and a great deal of laboratory space.

The Automated Plate Assessment System (APAS®) is a novel device dedicated to screening agar plates. Using image analysis technology, it is able to detect colony growth, enumerate the various colony types detected and apply standard microbiological rule sets to sort each plate into categories suitable for further processing. In this study, APAS® also applied an expert system specifically for the interpretation of urine cultures.

A total of 526 urine specimens from two separate laboratories were cultured and analysed by an APAS® prototype device. These results were then compared with those generated by experienced microbiologists.

In one laboratory, two hundred and seventy six urines submitted for routine culture were inoculated onto Horse Blood Agar and Brilliance™ UTI Clarity Agar bi-plates (Thermo Fisher Scientific, Thebarton, Australia). In the other laboratory, two hundred and fifty urines were inoculated onto Horse Blood Agar and MacConkey (No Salt) Agar bi-plates (Thermo Fisher Scientific, Thebarton, Australia).

Following incubation, the plates were read by experienced microbiologists and then analysed by a prototype APAS® instrument (LBT Innovations Ltd, Adelaide, Australia).

The results were then compared.

This study demonstrated the ability of image analysis technology to read and interpret cultures on agar plates.

Using APAS® to screen routine urine cultures produced results with an overall diagnostic sensitivity of 97% and specificity of 95%.

APAS® was able to detect and enumerate colonies and provided a preliminary identification for the primary isolates on the different agar combinations used by the two laboratories.

The incorporation of an expert system with standard reporting rules further enhanced the usefulness of the system.

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Poster Session A, 6 July
Australian Society of Microbiology
Melbourne 2014