MITIGATION OF ENTEROHAEMORRHAGIC ESCHERICHIA COLI ON MEAT CONTACT SURFACES USING PHYTOCHEMICALS
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Date
2018
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
The present study was undertaken to study the occurrence of
Enterohaemorrhagic E. coli (EHEC) on meat contact surfaces from retail meat
outlets. A detailed study was also done regarding the biofilm forming ability of
EHEC isolates and the effect of phytochemicals viz., trans-cinnamaldehyde and
eugenol in reducing the growth of EHEC on meat contact surfaces. The antibiofilm effect of these phytochemicals was analysed. A total of 245 swab samples
comprising of meat cutting board and knife surfaces were collected from four
retail meat outlets located in and around Thrissur district during the period of
study from November 2017 to June 2018. All the swab samples were subjected to
isolation and identification of E. coli and Enterohaemorrhagic E. coli by
conventional culture technique. The characteristic colonies from Cefixime
Tellurite-Sorbitol MacConkey Agar were selected and inoculated into tryptic soya
broth (TSB). The broth culture was subjected to multiplex PCR for detecting the
virulence genes viz., stx1, stx2, eaeA and hlyA. A total of 40 EHEC isolates
comprising of 30 isolates from cutting board and 10 isolates from knife surfaces
were obtained. The occurrence of EHEC recorded from four retail meat outlets
was 12 per cent, 21.42 per cent, 18.88 per cent and 5.71 per cent respectively. The
higher occurrence was recorded from second retail meat outlet (21.42%) in
comparison with other retail outlets from Thrissur district. All the 40 positive
isolates were analysed for its biofilm forming ability and of which only five per
cent of isolates had biofilm forming ability. Further, minimum inhibitory
concentration (MIC) of phytochemicals was determined against biofilm producing
EHEC and the MIC for trans-cinnamaldehyde and eugenol was found to be 3.5
per cent and 5.5 per cent respectively. The effect of these phytochemicals in
reducing the growth of EHEC on meat contact surfaces was also analysed. The
two concentrations of each phytochemical was studied.
A concentration of 3.5 per cent and 4.0 per cent of trans-cinnamaldehyde
brought about 0.66 and 0.69 log10 cfu/ml reduction of EHEC organisms on wood
in comparison with control of 5.42 log10 cfu/ml respectively. Eugenol at 5.5 per
cent and 6.0 per cent showed total reduction of EHEC organisms on wood. To
study the anti-biofilm effect of these phytochemicals, EHEC biofilms were
artificially created on wodden and fiber surfaces and the effect of two different
concentrations of each phytochemical were tested. A concentration of 3.5 per cent
of trans-cinnamaldehdye and 5.5 per cent of eugenol showed reduced growth of
EHEC biofilm whereas concentrations of 4.0 per cent of trans-cinnamaldehyde
and 6.0 per cent of eugenol completely inhibited biofilm forming EHEC. Hence
these phytochemicals can be used as a good sanitizers in order to reduce the
growth of EHEC which also had a significant effect on its biofilm forming ability.