8/9/2019 Characterisation of Bacteria

1/20

Based on phenotype

8/9/2019 Characterisation of Bacteria

2/20

Study of diversity of microorganisms andtheir relationships

Includes:clasi cation (ordering of B. into groups)nomenclatureidenti cation

8/9/2019 Characterisation of Bacteria

3/20

Morfological (cels including staining) Cultural Physiological

utritional Biochemical !cological "enetic #ntigenic Phage suscepti$ility

8/9/2019 Characterisation of Bacteria

4/20

#s many charactes as posi$le should $estudied

descri$tion of ne% species

8/9/2019 Characterisation of Bacteria

5/20

um$er of tests applied should $e &ept toa minimum

concetration for simple methods and for

characters %ith very good distinguishing value

tests must $e standardi'ed

8/9/2019 Characterisation of Bacteria

6/20

8/9/2019 Characterisation of Bacteria

7/20

0.1est for o*ygen re2uirements 3.1est for dissimilation of glucose

(o*idative4fermentative) 5.Select tests useful for distinguishing

$et%een the genera 6.Select the test apllica$le for species

identi cation

8/9/2019 Characterisation of Bacteria

8/20

7etermination of shape "ram reaction Motlity

8/9/2019 Characterisation of Bacteria

9/20

8*idase test Catalase test Car$ohydrate $rea&do%n 8+9 of glucose #cid formation from sugars "as formation from glucose 8 P" test ($eta+galactosidase activity)

8/9/2019 Characterisation of Bacteria

10/20

eduction of nitrate to nitrite Indole test ;P test (acetoin production) #rginin dihydrolase test

8/9/2019 Characterisation of Bacteria

11/20

( Sulphide Indole Motility medium) +com$ination di

8/9/2019 Characterisation of Bacteria

12/20

8/9/2019 Characterisation of Bacteria

13/20

1he IMViC tests are a group of individualtests used in micro$iology la$ testing toidentify an organism in the coliform group

# coliform is a gram+ = aero$ic orfacultative anaero$ic rod %hich producesgas from lactose %ithin /6 hours.

1he presence of some coliforms indicatefecal contamination.

8/9/2019 Characterisation of Bacteria

14/20

8/9/2019 Characterisation of Bacteria

15/20

Species Indole Methyl ed ;oges+Pros&auer Citrate

Escherichia coli

Positive Positive egative egativeShigella spp. ? @ egative Positive egative egative

Salmonella s pp. egative Positive egative Positive

Klebsiella sp p. egative egative Positive Positive

Proteusvulgaris ?,@ Positive Positive egative egative

Proteusmirabilis egative Positive egative Positive

Enterobacter aerogenes egative egative Positive Positive

these IMViC tests are useful for differentiating thefamily Enterobacteriaceae, especially when used alongsidethe Urease test.

The IMViC results of some important species are shownbelow.

http://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Shigellahttp://en.wikipedia.org/wiki/Shigellahttp://en.wikipedia.org/wiki/IMViChttp://en.wikipedia.org/wiki/IMViChttp://en.wikipedia.org/wiki/Shigellahttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_coli

8/9/2019 Characterisation of Bacteria

16/20

contains general nutrients and 5% sheep blood It is useful for cultivating fastidious organisms 4determining the hemolytic

capa$ilities of an organism. Some $acteria produce e*oen'ymes that lyse red $lood cells and degrade

hemoglo$inA these are called hemolysins. Bacteria produce di

8/9/2019 Characterisation of Bacteria

17/20

This streptococcus pyogenesexhibits β-hemolysis.

Examples of the blood culture patterns created by (from left)alpha-, beta- and gamma-

hemolytic streptococci.

8/9/2019 Characterisation of Bacteria

18/20

"iven a mi*ed $roth culture containingStaphylococcus aureus, Bacillus subtilis,Salmonella typhi and Shigella

dysenteriae, descri$e a systematicapproach to separate and con rm theidentity of each of these $acteria .

( 5 mar!s"

8/9/2019 Characterisation of Bacteria

19/20

1%enty students %ere hospitali'ed afterta&ing $rea&fast from a school canteen. #sample of drin& from the canteen %as sentto a micro$iologist to determine the causeof the pro$lem. 1he only informationavaila$le is that the sample contains grampositive cocci $acteria. #s a micro$iologistdescri$e a systematic approach todetermine the concentration of $acteria inthe sample and the identity of the $acteria.

( 0 mar&s)

8/9/2019 Characterisation of Bacteria

20/20

1here are three (,) di