In search of a counter you can count on: relative efficacy of human visual and automated colony counting.
Lett Appl Microbiol
; 66(3): 188-193, 2018 Mar.
Article
en En
| MEDLINE
| ID: mdl-29341168
To evaluate comparative efficiency of traditional vs automated colony counting methods, cultures of Escherichia coli (ATCC 25945), Staphylococcus epidermidis (ATCC 12225), Streptococcus pyogenes (ATCC19615) and Streptococcus pneumoniae (ATCC49619) were prepared as pure cultures and mixed cultures at 0·5 McFarland standard and serial dilutions were performed. Plates were inoculated in triplicate with 50, 125, 250 and 500 colony forming units and counted by four researchers, visually and using each of the automated counters. Colony count and counting time were recorded. The pattern of efficiency for all bacterial species was similar: plates with low counts were accurate and quick to count for all methods, with an increase in time and a decrease in accuracy and precision as counts rose. Higher counts of single round colonies required less time and had greater precision with automated counters than human visual counting counts with no loss of accuracy; however, counts were reduced in accuracy and increased in time for species with less regular morphology or when plates had mixed species. Surprisingly, a free phone application was only slightly less precise and more time consuming than the high-end professional counter indicating that automation may be achievable at lower cost than expected. SIGNIFICANCE AND IMPACT OF THE STUDY: Colony quantification is essential in clinical and research settings as well as pedagogy at the college level. Human visual (HV) counting, the most common method, is time consuming and fraught with errors. The time, accuracy and precision of HV counting were compared to a high-end professional automated counter, an inexpensive phone application and a free phone application. Low cost benefits of increased speed and accuracy with automated counting are maximized when counting single round colonies; but much reduced if colonies have irregular morphology or demonstrate haemolysis.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Automatización
/
Staphylococcus epidermidis
/
Streptococcus pneumoniae
/
Streptococcus pyogenes
/
Escherichia coli
Tipo de estudio:
Diagnostic_studies
/
Evaluation_studies
Límite:
Humans
Idioma:
En
Revista:
Lett Appl Microbiol
Asunto de la revista:
MICROBIOLOGIA
Año:
2018
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Reino Unido