Agriculture Reference
In-Depth Information
competitive exclusion of pathogens by background microfl ora is minimized by the
use of pathogen-inoculated seeds, and this methodology more closely approximates
naturally occurring contamination of seeds.
Conclusions
The number of outbreaks linked to fresh produce reported to the CDC has increased
in the last years (Bean and Griffi n 1990; CDC 2000). This increase may be due in
part to improved surveillance, but other factors may also come into play. Proposed
reasons include the signifi cant increase in the consumption of fresh produce in the
United States due to the growing awareness of fruits and vegetables as a part of a
healthy diet. Also, greater volumes of minimally processed produce are being shipped
from central locations and distributed over much larger geographical areas to meet
the increased popularity of salad bars. This, coupled with increased global trade,
signifi cantly increases human exposure to a wide variety of foodborne pathogens and
also increases the chances of outbreaks (Harris and others 2003).
To minimize the possibility of outbreaks, producers such as the International Sprout
Growers Association (ISGA) have taken positive steps to address this problem by
pursuing the use of 2% calcium hypochlorite for soaking alfalfa seeds prior to germi-
nation and growth. This intervention method has the potential to substantially reduce,
but not necessarily eliminate, pathogenic microbial contamination of seeds that can
be passed on to the consumer through ingestion of raw sprouts. Thus, the development
of effective technologies that can be applied to detect pathogenic bacteria in produce
is desirable.
In this chapter, we provide evidence demonstrating that a combination of IMB to
capture and biosensors to detect (a method that was originally developed for detecting
pathogens in meats) has the potential to detect low levels of pathogenic bacteria in
produce, specifi cally cantaloupes and alfalfa seeds and sprouts. The sensitivity of
developed IMB-TRF processes allows rapid detection, within an 8-h shift, of select
pathogens even in the presence of high levels of the background microfl ora. In prin-
ciple, the technology may be applied to the detection of pathogens in other produce
that are of outbreak concerns. The availability of magnetic bead manipulator and
biosensor detector in 96-well formats will certainly increase the feasibility of high-
throughput screening of pathogens in meats and produce.
Disclaimer
Mention of brand or fi rm names does not constitute an endorsement by the U.S.
Department of Agriculture or any other federal agency or governmental entity over
others of similar nature not mentioned.
References
Ackers ML , Mahon BE , Leahy E , Goode B , Damrow T , Hayes PS , Bibb WF , Rice DH , Barrett TJ ,
Hutwagner L , Griffi n PM , and Slutsker L . 1998 . An outbreak of
Escherichia coli
0157:H7 infections
associated with leaf lettuce consumption . Journal of Infectious Disease 177 : 1588 - 1593 .
Anderson GP , Golden JP , and Ligler FS . 1993 . A fi ber optic biosensor—combination tapered fi bers designed
for improved signal acquisition . Biosensors and Bioelectronics 8 : 249 - 256 .
