Rickettsia Staining by using Gimenez Method

Aim

To stain Rickettsia by using Gimenez staining method.

Approach

Rickettsia is a non-motile, Gram-negative,non-spore forming, pleomorphic bacteria. It is pleomorphic because it shows different shapes of bacteria that is cocci, rod and spiral shape.

Rickettsia name was given by scientist Howard Ricketts. It is an obligate intracellular parasite and this micro-organism is responsible for the cause of infection like Rocky mountain fever, Typhus and scrubs typhus infection. It generally infects the eukaryotic cell and these infection doesn’t spread directly by air, water or soil it requires a carrier to carry these infection from one host to another host. This infection is generally carried by carrier like blood-sucking arthropods. As Rickettsia is infectious its detection is very important and for its detection staining of these organisms is one of the initial and important steps.

Requirement

  1. Gimenez stain
  2. Malachite green
  3. Bacterial culture

Procedure

  1. Prepare a smear on a clean grease free slide, air dry and heat fix the smear.
  2. Treat the smear with Gimenez stain for about 2-3 minutes.
  3. Water wash the slide and treat the smear with counterstain that is Malachite green for about 2-3 minutes.
  4. After 2-3 minutes water washes the slide, air dry and observe under oil immersion lens.

Mechanism

Gimenez stain is made up of basic fuchsin, ethanol and phenol, sodium Di-hydrogen phosphate and Di-sodium hydrogen phosphate. Gimenez stain has a property to stain both type of bacteria that is Gram positive as well as Gram negative bacteria. Basic fuchsin stains negatively charged cytoplasm and stains cytoplasm in red colour. Whereas when we treat smear with Malachite green and as we know malachite green is a basic dye it has a strong affinity towards host cell material as compared to the cytoplasm and so it stains host cell material that is the background of the cell in bluish green colour.

Flow chart for staining of Rickettsia by Gimenez Staining technique.

Flow chart of Rickettsia staining Procedure by Gimenez method
Flow chart of Rickettsia staining Procedure by Gimenez method

Observation

Red colour stained bacterial cells are observed against the bluish-green background.

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