Comparison of ELISA and PCR vis-a`-vis cultural methods for ...

182
locations may be the possible reasons for these variations in
incidence rates of Aeromonas in poultry.
One of the 50 milk samples screened turned out to be
positive for Aeromonas. This also gave positive result with all
three methods viz., duplex-PCR (Fig. 1), I-ELISA as well as
cultural method. The incidence rate of Aeromonas in milk thus
was 2.0% which was comparable to the isolation rate of 2.85%,
5.56% and 4.0% reported by Agarwal et al. (2000), Kumar et
al. (2001) and Porteen (2004), respectively.
The study revealed that there was a good correlation
between duplex-PCR and cultural method but indirect-ELISA,
though detecting all naturally contaminated chicken and milk
samples, was not able to detect Aeromonas below the
concentrations of 10 3 cells/ml or g in the spiking studies. This
limits the use of indirect-ELISA as a fool-proof detection
method for aeromonads in foods when compared to PCR.
Thus, it can be concluded that both OMP based indirect
plate ELISA as well as duplex-PCR, following 12 h enrichment
in APW-C, are reliable methods for detection of Aeromonas
from foods of animal origin on account of their specificity; and
duplex-PCR, following 12 h enrichment in APW-C, is the
method of choice amongst the three methods compared in this
study on account of its rapidity and sensitivity as well as
specificity.
Acknowledgements
The authors are thankful to the Director, Indian Veterinary
Research Institute (IVRI), Izatnagar, Bareilly (UP), India for
permitting the first author to conduct this work at IVRI.
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