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A COMPANY SERVE FOR STUDENTS
T20 TOCOPRODUCTS & Pvt. Ltd
PROUDLY INTRODUCING
T20 EXAM PATTERN
BY T20 TOCO PRODUCTS & Ltd.
IN ASSOCIATION WITH
THE TAMILNADU DR. MGR
MEDICAL
UNIVERSITY
REDUCING THE
EXAM TIME BY
ONE HOUR
AND
MARKS BY 50
FIRST 30 mins. POWER PLAY
NO SUPERVISOR
IN THE HALL
CHEER GIRLS IN EVERY
CLASS.
THEY WILL DANCE
AFTER FININSHING
EVERY PAGE
COUNTING
OF
BACTERIA
BACTERIAL COUNT
COUNT OF LIVING AND DEAD CELLS
TOTAL COUNT.
COUNT OF ONLY LIVING OR VIABLE CELLS
VIABLE COUNT.
TOTAL COUNT METHODS

Direct methods:
 Breed’s
method
 Wright’s
method
 Counting
 Coulter
Chamber
counter method
 Membrane
filtration
Total count methods

Indirect methods:
 Visual
method
 Photometric
method
 Colorimetry
 Nephlometry

Packed cell volume

Dry weight
VIABLE COUNT

SOLID MEDIA TECHNIQUE
 Pour
plate method
 Surface
 Drop
viable method
technique
 Spreading
techinque
VIABLE COUNT

ROLL TUBE METHOD

MEMBRANE FILTERATION

FLUID MEDIA TECHNIQUE

COUNTING ANEAROBES
TOTAL COUNT – BREED’S
METHOD

Microscopic slide – mark 01 sq.mm
area

Place stage micrometer in the eye
piece

Dilute the suspension – spread
carefully on the sq.mm area of the
slide – dry it – fix it – stained –
counted at the squares.
DO YOU KNOW THESE?

SIZE OF SQUARE IN THE EYEPIECE

AREA OF FLIM ON THE SLIDE

VOLUME OF SUSPENSION TAKEN on the
slide


If you know ……………….
THEN THE NUMBER OF ORGANISMS IN
THE ORIGINAL SUSPENSION CAN BE
CALCULATED.
WRIGHT’S METHOD

Equal volumes of suspension and
blood is intimately mixed.

Made a smear on the slide.

Fixed – stained – counted

Number of bacteria and red cells are
counted for 40 fields.

Number of RBC - 5X106 per cm2
As
the ratio of blood
cells to bacteria on
the slide is known,
the number of
3
bacteria per cm in
the suspension can be
found by
proportionality.
COUNTING CHAMBER
Slide with recessed area that is ruled
in squares.
 Drop of culture is placed over that
and place a cover slip.
 Don’t allow any air to entrap
 Allow to settle the cells on the area
 View under phase contrast
microscope
 Stain and focus under normal micros.


Number of organisms in 04 groups of
16 small squares are counted
Cover glass
Ditches
Grid
Depressed cell
Suspension cel
End view
CIRCULAR DITCH CELL
STRAIGHT DITCHES
COULTER COUNTER METHOD
Flow of suspension
Tube
Electrode
Electrode
Orifice
Suspension
MEMBRANE FILTRATION

Provided that the suspension could be sufficiently
diluted

Organism retained on the filter are stained – dried
– counted under microscope

The number of bacteria on the filter paper, from a
known volume of suspension can be calculated
Mostly applicable when the numb of organism is very small .
INDIRECT METHODS
COMPARISION WITH
STANDARD
SUSPENSION
VISUAL METHOD

Use of std. opacity tubes.

10 tubes – solid suspn. of unglazed
porcelain in increasing OD.

They are standardized against accurately
counted bacterial Suspension.

Comparing the opacity with standards.
PHOTOMETRIC METHOD

SPECIAL FILTER
OPTICAL CELL
CALORIMETRY
METER
PHOTO
CELL
READING
NO. OF CELLS
SHUTTER
AMOUNT OF LIGHT ABSORBED BY THE
SUSPENSION IS CALCULATED
LIGHT
SOURCE
NEPHLOMETRY
THE AMOUNT OF LIGHT
REFRACTED BY THE
PARTICLES IN THE
SUSPENSION IS MEASURED
PACKED CELL VOLUME



Suspension is centrifuged
Depth of sediment is measured
Equivalent num. of cells is obtained
from a graph of cell numbers against
paced cell volume
DRY WEIGHT

Centrifuged cells – washed,
dried – weighed

Weight can be related to number of cell
COLONIES
VIABLE COUNT
ROLL TUBE METHOD
SOLIDIFIED
AGAR MEDIA
LAYER
The rubber closure should be loosened during incubation
MEMBARANE FILTRATION
MEMBRANE FILTER IMPREGNATED WITH
MEDIUM
BY STEREOSPECIFIC MICROSCOPE AND
SURFACE ILLUMINATOR – COUNTING
CAN BE DONE
USING A FILTER OF 47 TO 50 MM DIAMETER – UP
TO 200 COLONIES CAN BE COUNTED
FLUID MEDIA TEECHNIQUE
THANK YOU
I ACKNOWLEDGE MY MISTAKES IF ANY
Meet again