Furazolidone Disk Test- Principle, Procedure and Results

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Purpose

Furazolidone susceptibility testing is a reliable method for differentiation of Staphylococci from Micrococci based on their susceptible.

Principle

There are several methods available for differentiation of staphylococcifrom micrococci. One of these is susceptibility to the compound furoxone (also called furazolidone). This test is performed as a disk susceptibility procedure; Staphylococci are susceptible to this compound, whereas micrococci are resistant.

Media and Reagents

Furazolidone disks, 100 mg

Mueller Hinton Agar

Quality Control

Known strains of Staphylococcus (either S. aureus or a coagulase-negative strain) and Micrococcus species should be tested with each new lot of disks, or on a weekly basis.

Test Procedure

Prepare a suspension of the organism to be tested in sterile peptone water. The suspension should be equivalent to a 0.5 McFarland turbidity standard.

Spread the organism suspension onto MHA plate by using swab.

Aseptically place a Furazolidone disk in the centre of the inoculated plate, and gently tap the disk so that it adheres to the agar surface.

Incubate the plate at 37°C in an ambient-air incubator for 18–24 hours.

Results and Interpretation

Micrococcus species are Furazolidone -resistant and will have zones of 6 mm (no zone) to 9 mm.

Staphylococcus species are Furazolidone -susceptible and will have zones of inhibition of >15 mm.

Furazolidone susceptibility test
Reference

  1. Koneman’s Color Atlas and Text book of Diagnistic Microbiology.
  2. Bailey and Scott’s Diagnostic Microbiology.


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