Real Time PCR versus Conventional Methods For Detection of Viable But NonCulturable E. Coli O157 Isolated From Food of Animal Origin

Document Type : Original Article

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Abstract

Escherichia coliO157:H7 consider an important zoonotic food borne pathogen that cause
bloody diarrhea, hemorrhagic colitis (HC), hemolytic-uremic syndrome (HUS), and
thrombotic thrombocytopenic purpura (TTP) in human. E. coli O157:H7 use a viable but
non culturable (VBNC) state as a survival strategy which regarded as a threat to food
security and the health of society. In this dormant stage, pathogens can evade
identification by standard techniques. So, PCR methods are used for identifying all
viable (culturable and non-culturable). This study was performed on 500 samples (300
raw meat and 200 raw milk samples) collected from different supermarkets allover
Menoufia, Egypt. Samples were subjected to conventional culture method then positiveculture samples were confirmed by biochemical and serological identification while
negative-culture sample subjected to conventional PCR and PMA in combination with
SYBR green real-time PCR for VBNC E. coli O157:H7 detection. The obtained data
showed that the incidence of E. coli O157:H7 by the conventional method was 3% while
the incidence of VBNC E. coli O157:H7 by PMA with SYBR green real-time PCR together
was 10% for ten tested samples and 0.21% of 475 negative-culture samples. This
study revealed that conventional and immunoassay methods were unable to identify
VBNC case, also conventional PCR is unable to distinguish between dead and live
bacterial cells. However, employing a real-time PCR technique alongside PMA has the
necessary efficiency and sensitivity for identifying all viable (culturable and nonculturable) E. coli O157:H7.

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Journal of Current Veterinary Research
Volume 5, Issue 2
October 2023
Pages 106-120

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