Urine colony counts. inoculate the agar plate
to perform a urine colony count, inoculate the agar plates with one micro
liter of urine. the sterile loop is calibrated to hold 1 micro litre.
Pass this loop down the center of the plate and carefully spread the urine over the
entire plate. incubate the plates overnight at 37 degrees Celsius. let's
take a look. on account setup requires: the agar plate to grow the organisms on
a 1 micro litre loop and the urine specimen. you take the 1 micro litre
calibrated loop, this is sterile, open carefully, and we'll pick up one loop full
which is calibrated to be 1 micro litre of specimen. it is streaked straight down
the center of the plate and then back-and-forth to spread out the colony
so that you can get a colony count reading after it has incubated.
Diagram of urine culture inoculation procedure: first streak down the middle of the
plate, next streak from side to side to distribute the organisms evenly on the
agar plate. reading the plates: after the plates have incubated count each colony
on the plate each colony represents one bacterium which forms a colony and is
called a colony forming unit. counting the colonies: count the number of
colonies on the plate. this is the number of colonies per 1 micro litre of urine.
use the conversion factor to convert 1 micro litre to one milliliter. counting
the colonies the calculation: colonies per plate 54 ammount plated 1 micro
litre. here's the calculation. the micro liters cancel and you are left with
54,000 colonies per 1 millilitre. note if you
counted 50 or 52 or 56 for this sample no problem just use the number you
counted in your calculations. your answer will be different from the answer above
but the exponent will be the same. also always remember to put the units of
colonies and milliliters in your calculations and in your answer.
counting the colonies. the number of colonies on this plate is greater than
100. the number used for your calculations is greater than 100
colonies per one microliter. use your conversion factor to convert this value
to colonies per milliliter of urine.
counting the colonies the calculation. colonies per plate greater than 100.
amount plated one microliter here's the calculation the micro liters cancel and
you are left with greater than 100,000 colonies per one milliliter note
remember to put the units of colonies and milliliters in your calculations and
in your answer you must use the greater than sign in your answer count the
colonies count the number of colonies on this plate this is the number of
colonies per 1 micro litre of urine use the conversion factor to convert 1 micro
litre to one milliliter counting the colonies calculation colonies per plate
75 ammount plated 1 micro litre here is the calculation the micro liters cancel
and you're left with 75,000 colonies per one milliliter. note if you count in a
slightly different number no problem, just use the number you counted in your
calculations your answer will be different from the answer above but the
exponent will be the same also always remember to put the units of colonies
and milliliters in your calculations and in your answer counting the colonies now
count the number of colonies on this plate this is the number of colonies per
1 micro litre of urine. use the conversion factor to convert 1 micro
litre to one milliliter.
counting the colonies calculation colonies per plate greater than 100 a
mouch plated one microliter here's the calculation the microliters cancel and
you're left with greater than 100,000 colonies per one milliliter in summary
certain criteria are used to evaluate a clean catch midstream urine colony
counts to determine if it represents an infection a few bacteria will typically
be present on the agar from a clean catch urine colony count because the
urine is contaminated with skin organisms as it leaves the urethra.
if there is an infection it is usually due to just one type of organism cultures
with more than three organisms present on the agar are most likely contaminated
the following results are typical of a urinary tract infection: high colony
counts of one organism especially greater than 100,000 are indicative of
an infection. lower counts can also indicate an infection. in some
circumstances white blood cells are seen on the microscopic evaluation of the
urine. very few epithelial cells are seen on the microscopic evaluation all urine
cultures should be taken to the laboratory or stored in the refrigerator
as soon as possible after collection to retard replication of organisms in the sample.
this concludes this activity urine colony counts