Towards the production of reliable quantitative microbiological data for risk assessment: Direct quantification of Campylobacter in naturally infected chicken fecal samples using selective culture and real-time PCR
Garcia Clavero, Ana Belén1; Vigre, Håkan1; Josefsen, Mathilde Hasseldam3
1 National Food Institute, Technical University of Denmark2 Division of Epidemiology and Microbial Genomics, National Food Institute, Technical University of Denmark3 Division of Food Microbiology, National Food Institute, Technical University of Denmark
Poultry has been identified as a significant source for human campylobacteriosis which constitutes an important zoonosis and public health problem in many areas of the world. Rapid, direct and accurate quantification of Campylobacter in poultry is essential for the assessment of public health risks and for the evaluation of control strategies implemented in poultry production. The aim of this study was to compare estimates of the numbers of Campylobacter spp. in naturally infected chicken fecal samples obtained using direct quantification by selective culture and by real-time PCR. Absolute quantification of Campylobacter by real-time PCR was performed using standard curves designed for two different DNA extraction methods: Easy-DNA™ Kit from Invitrogen (Easy-DNA) and NucliSENS® MiniMAG® from bioMérieux (MiniMAG). Results indicated that the estimation of the numbers of Campylobacter present in chicken fecal samples was partly dependent on the methodologies used. In general, the numbers of Campylobacter obtained by real-time PCR when extracting DNA using the MiniMAG method were in most cases higher than the numbers of Campylobacter obtained by selective culture and by real-time PCR when using the Easy-DNA method. Although there were differences in terms of estimates of Campylobacter numbers between the methods and samples, the differences between culture and real-time PCR were not statistically significant for most of the samples used in this study.