THE CATALASE TEST

Catalase & coagulase test By-Dr.Aliya shah Moderators-Dr. Ritu Garg Dr.Varsha. A Singh THE CATALASE TEST

REAGENTS 3%HO OR 30% HO brown bottle refrigeration 18 to 24 hour culture

Principle : 2HO

catalase enzyme

HO +O (Gas bubble)

Quality control

HO-unstable chemical.

check daily or immediately prior to use.

CONTROL STRAINS

positive -staphylococcus aureus ATCC 12600 Negative- streptococcus pyogenes ATCC 12344 Procedure

Slide catalase-3% HO glass rod/ wooden spatula growth

3%HO

30% catalase Incubate 14 days 30% HO

LJ Media 45mm (-) (+)

30% catalase peroxidase test

Differentiate Tubercle bacilli weakly positive Atypical mycobacterium-strongly positive

Indicateisoniazid sensitivity INH(S) INH(R) (catalase ve) (catalase +ve)

Tube catalase

Interpretation:-

rapid and sustained bubbles or effervescence

A few tiny bubbles after 20 to 30 seconds- not a positive USES 1. Genera differentiation

Streptococcus from micro and staphylococus. Positive- Micrococus Staphylococus(except S.sacharolyticus)Negative- Streptococus

2. species differentiation Positive- Staphylococcus aureus subspecies anaerobius and Staph saccharolyticus from other staphylococcus species.

Others Positive Negative Listeria monocytogensCornybacterium (except C.pyogens & C.hemolyticus)Moraxella sp (except kingella kingae)Enterobacteriae (except S.dysenteriae)Gonococcus & meningococusVibrio choleraPseudo /Aero/plesiomonas

Erysipleothrix

COAGULASE TEST Media and reagents Rabbit plasma EDTA Commercially available in lyophilized form. Reconstituted plasma - refrigerated .Human plasmaFree sodium citrate Citrate not to be used it may be utilised by some contaminant bacteria causing false positive results.Types of coagulase

Bound and free

1. Free coagulase S.aureus subspecies S anaerobius ,S hyicus

2. Bound coagulase S lugdunensis ( negative for free coagulase)

Coagulase

Positive NegativeS.aureusS.hyicusS.intermediusS.haemolyticusS.epidermidisS.saprophyticusS.huminisusesdifferentiate species within the Genus Staphylococcus aureus.

indicate virulence or pathogenesis staph species.

PRINCIPLE:

Coagulase (protein) , prothrombin like activity

which converts fibrinogen into fibrin

a visible clot results 3 .Quality control 1)Coagulability of plasma - drop of 5 % calcium chloride+ 0.5ml plasma.

2)A clot within 10 to 15 seconds .

3) staph. aureus strain -positive staph. epidermidis strain -negative

4) 18 to 24 hours cultures of the control strains.

Bound coagulase Bound coagulase also known as clumping factor

Attached to the bacterial cell wall

Fibrin strands are formed between the bacterial cells

when suspended in plasma(fibrinogen)

visible clumps formed

Slide coagulase test-procedure

Interpretation:- Slide test 1) within 10 to 15 seconds formation of clumps

2) negative-if no clumps after 2 minutes the saline control should remain smooth and milky.

3)Control clumps formed ,uninterpretable.

Free coagulase Thrombin like substance present in culture filtrates.

suspension of coagulase producing organisms is prepared in plasma in a test tube .

Clot forms as the result of coagulase reacting with a serum substance.

Complex reacts with fibrinogen to form clot. Tube test -procedure Incubate at 35 4 hrs

Interpretation :-Tube test positiveany degree of clotting is noted. gently tilted / not agitated - disrupt partially formed clot. Fibrinolysins - dissolve the clot .

Negative after 4 hours should be incubated at room temperature overnight and read after 18 hours .

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