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E.coli in drinking water
One of hundreds of strains of the bacterium Escherichia coli,
E. coli O157:H7 is an emerging cause
of foodborne and waterborne illness. Although most strains of E. coli are harmless and live in
the intestines of healthy humans and animals, this strain produces a powerful toxin and can
cause severe illness. E. coli O157:H7 was first recognized as a cause of illness during an
outbreak in 1982 traced to contaminated hamburgers. Since then, most infections are believed
to have come from eating undercooked ground beef. However, some have been waterborne. Last year,
people became sick after drinking contaminated water in Washington County, New York and swimming
in contaminated water in Clark County, Washington. Information about the health effects of
E. coli
O157:H7, and actions you can take to protect yourself and your family from
E. coli infection is
provided below. You can also read the Centers for Disease Control and Prevention's
What
does Colitag test for?
Colitag tests both drinking water
and food for O157, O143 and O145 E. coli and both total and fecal
coliforms.
What is Colitag’s detection limit?
1 colony-forming unit (CFU) of
E. coli or total
or fecal coliform bacteria per 100-mL water sample.
What is
Colitag EPA-approved for?
As of
June 23, 2010, Colitag™ is EPA-approved for drinking water
and ground water testing, and is currently awaiting approval for
wastewater testing. Labs who are located in states that follow
stricter regulations than the ones listed in the EPA’s certification
manual should contact their state’s certification officer to see if ColitagTM is approved for use in that state for the testing that you
are conducting, or our office at 800-878-7654.
Colitag product is approved for Most
Probable Number (MPN) format as specified in Standard Method 9221
for compliance monitoring of total coliforms and E. coli in drinking
water
What type of
facility and equipment do I need in order to properly use ColitagTM?
A room that is cool, dry and away from light, a
100-mL sample of water, an incubator and a long wave-length
(365-nanometer) ultra-violet lamp
Under
what temperatures and conditions should Colitag™ be stored in before
it is used?
Colitag™ should be stored away from light in a cool and dry
room with a temperature between 4.0 degrees Celsius and 30.0 degrees
Celsius (the standard temperature of a laboratory).
At what
temperature should a Colitag™ sample be incubated at?
35 degrees Celsius plus or minus 0.5 degrees Celsius. This should
be the incubator’s temperature regardless of whether you’re
conducting the 16-22 hour test or the 22-48 hour test. If you are
planning on reading the sample between 16-22 hours, then the sample’s
vessel should be at a temperature of 33-38 degrees at its time of
incubation. If the sample is not at this temperature, then its vessel
should be placed in a 44.5 degrees Celsius water
bath for 7 to 10
minutes before being placed in the incubator.
What is
the shelf life of Colitag™?
22 months from its manufacturing date.
Expiration dates are printed on each Colitag™ box and individual
blister.
What
should Colitag™ look like when I initially receive it?
It should be granulated, powdery and off-white
(a little darker than white but significantly lighter than grey).
Each blister should contain about a gram and a half of the media.
How do I
determine whether or not my sample is positive or negative for E.
coli or total or fecal Coliforms?
If the sample is clear then it is negative for
E. coli and total and fecal coliforms. If the sample is yellow and
of equal or greater color than the yellow Colitag™ Comparator (P/A),
then it is positive for coliforms and may be positive for E. coli
(the sample is negative for E. coli and total and fecal coliforms if
it is a lighter-colored yellow than the color of the Colitag
Comparator). You then use a long wave-length (366-nanometer)
ultra-violet lamp to check the sample for fluorescence. If the
sample gives off a bright blue fluorescence, then it is positive for
E. coli. If it does not fluoresce, then it is still positive for coliforms but negative for E. coli.
Can I
ever read a sample before 16 hours or after 22 hours using the
procedures for the 16-22 hour test?
A sample should never be read before 16 hours,
but can be read anytime from 22-48 hours after incubation for the 16-22 hour test.
We refer to it as the 16-22 hour test to clearly differentiate it from the 22-48 hour test,
as you cannot read the sample BEFORE 22 hours if you conduct the 22-48 hour test,
but you can read the sample’s results from 22-48 hours as well as from 16-22 hours if you conduct
the 16-22 hour test.
Can I
ever read a sample before 22 hours or after 48 hours using the
procedures for the 22-48 hour test?
No, as the Colitag™ medium needs to interact
with the water for at least 22 hours in order to produce an accurate
reading, and will have interacted with the water for too long if it
is incubated for more than 48 hours. The test is only valid if the
sample is analyzed between 22-48 hours.
I conducted the Colitag 22-48 hour
test. At 24 hours after incubation I observed that the sample was clear
or of a lesser yellow color than that of the Colitag Comparator (i.e.
negative for E. coli and coliforms or only positive for coliforms).
However, at 48 hours after incubation I observed that the sample was of
a greater yellow color than that of the Colitag Comparator (i.e. positive
for coliforms and possibly E. coli). Is the sample positive or negative
for E. coli and coliforms, and should I do anything else to confirm or
invalidate my test’s results?
Samples being negative for
coliforms and E. coli or only positive for coliforms at 24
hours after incubation (being clear or of a lesser yellow color than
that of the Colitag Comparator) but positive for coliforms and possibly
E. coli (being of a greater yellow color than that of the Colitag
Comparator) at 48 hours after incubation is possible and will inevitably
happen from time to time. Colitag has the lowest rate of false positives
and false negatives for any E. coli and coliform test that is
currently on the market, but no test is 100% foolproof, and thus while
being extremely rare, false positives and false negatives will occur for
the Colitag test.
Very late positives should be suspected (not assumed)
of the result of total coliforms that are either slow growers or
coliforms which do not grow very well under the conditions of the test
or whose growth is inhibited by the amount of other organisms around
them that grow faster. The best thing to do if you observe a late
positive or late negative sample is to transfer the sample to a
secondary confirmatory test.
Late positives for total coliforms can be
readily confirmed by any number of methods - the easiest of which would
be to inoculate the sample from the positive bottle into LTB/BGB tubes
and inspect it for gas & turbidity. This is also seen in the traditional
MPN test with LTB & BGLBB (SM9221) and why those tests run for 48 hours
for negative outcomes. If you encounter a late positive or late
negative test and are unsure of what you should do, please contact our
office immediately at 1-800-878-7654, or specifically contact Marketing
Director Brian Yniguez at ext. 320 or
yniguezb@cpiinternational.com.
I read a
sample during the correct testing period for the test that I was
conducting (whether it be the 16-22 hour test or the 22-48 hour
test) and correctly followed the listed procedures for my test.
The
sample was clear when I observed it, but I left it out on a counter
or in the incubator for more than a day, and it is now yellow. Does
this mean that the sample may be positive for E. coli or total or
fecal coliforms?
No, as the test is not valid after its testing
window has passed (22 hours for the 16-22 hour test or 48 hours for
the 22-48 hour test). Since the Colitag™ media contains various
chemicals, the sample will eventually turn yellow or another color
if it interacts with the water in the bottle for a long period of
time. This is just a natural occurrence, and nothing to be concerned
about. If you followed the proper procedures for either the 16-22
hour or 22-48 hour test and checked it within the proper testing
window and it came back clear, then it is definitely negative for
E.
coli and/or total or fecal coliforms.
How do I
properly dispose of a Colitag™ sample?
Usually all you need to do is sanitize the
bottle, but since Colitag™ is a bacteriological biohazard material,
you should refer to your local, state and/or federal authorities to
determine the disposal requirements that apply to your organization.
A Material Safety Data Sheet for Colitag™ can be acquired by calling
our office at 800-878-7654 or visiting
www.cpiinternational.com.
How do I
order Colitag™?
To order Colitag™, call our office at 800-878-7654, or visit
http://www.colitag.com/Products.html
to order through our
e-commerce store, where you can fill out a quick order form.
Which
credit cards does CPI
International accept?
We accept all major credit cards, such as Visa,
MasterCard and American Express. If you have a question in regards
to whether or not we accept your credit card, please call our office
at 800-878-7654 or email
marketing director Brian Yniguez at
yniguezb@cpiinternational.com
How long
does it usually take for a package of Colitag™ to arrive at my office
after I have placed the order?
It usually takes 3-5 days for the package to
arrive, and we offer same day shipping if the product needs to
arrive sooner. For international destinations, the shipping time
depends on how close our nearest distributor is to that destination.
Click here to view a list of our international and U.S.
distributors.
Can you
accommodate a specific shipping method of my choice for Colitag™?
Yes, assuming that the carrier is willing to
transport our products and that their method of transportation will
not damage the integrity of the Colitag™ medium. Request your
shipping method when you place an order, and we will do our best to
accommodate it.
I’m
concerned about my order, as it is past the expected shipping date
and I still haven't received it. What should I do?
Contact us immediately at 800-878-7654, and we will make sure that you
receive your package as soon as possible.
If you have any questions that were not
answered here, please contact our office at 800-878-7654 or email marketing director Brian Yniguez at
yniguezb@cpiinternational.com
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