Midt 2 PP- Jane

Question 1

How do we perform Neisser staining?

Answer 1

1. Neisser -I   2xVol 
   Neisser-II   1xVol 
      Mix these for for about 10 min
2. wash with water
3. Crisoiddine 1-2 min
4. Remove excess stain and dry with filter paper
5. Observer under microscope (immersion)

Question 2

Clauberg medium

Answer 2

Composed of Glicerin, blood, cystin and tellurite
The specimen reduce the tellurite to different extent –> grey- black colonies.
Gives a garlic smell

Typically used Corynebacterium diphtheria

Question 3

Löffler medium

Answer 3

Ivory color.
Composed of bovine serum, egg, heart extract.
Rapid growth, strong volutin granule formation.

Question 4

Oxidase test

Answer 4

Purpose: Detection of cytochrome.oxidase enzyme.
Diagnostic use: Differentiation of obligate aerobes.

Performance:

• Filter paper on microscope slide
• add oxidase reagent ( = parephenylene-diamine derivative)
• add bacteria
• postitive: pink/purple color

oxidase + bacterias: pseudomonas, Neisseria, Vibrio, campylobacter.

Question 5

Elek’s test

Answer 5

A filter paper strip is buried in the agar before it hardens, this paper have antitoxin on it. If the toxin binds the antitoxin we get a precipitation arch.

This test is used to test the toxigenicity for diphtheria.

Question 6

Coagulase test

Answer 6

1. Tube coagulase test: inoculating the bacteria into citrate treated rabbit plasma, coagulation occurs in a few hours.
2. Clumping test: fibrinogen-coated particles endocoagulase binds fibrinogen. Mix the bacteria with fibrinogen-bound latex particles on microscope slide –> clumping bacteria ( in a few sec)

Coagulase +: St. aureus
Coagulase -: all other staphylococci

Question 7

Catalase test

Answer 7

Aim: to diff between staph and street
Performance: mix the bacteria with H2O2 –> strong bubbling response if positive.

H2O2 –> H20 + O2