September 19, 2021: Pharmaceutical Interview Questions and Answers

#GrowthPromotionTestForBrothMedia #CopiousGrowthMethod #EndPointMethodsMethodOfGPT #MostProbableNumberMethodofGPT

1. What are the quantitative techniques of Growth Promotion Tests for Broth Media?

Quantitative techniques of Growth Promotion Tests for Broth Media are of four types.

● Copious Growth

● End-point Methods

● Most Probable Number (MPN)

● Kinetic Parameters

2. Explain Copious Growth method of Growth Promotion Tests for Broth Media?

This is the method of choice as per compendial. The challenge of broth media is done by comparing the growth over the period of time with a control batch (which provides a qualitative assessment of copious growth). In this method, the challenge organism is inoculated at a very low level (< 100 CFU per unit) and incubated at the prescribed temperature for the prescribed period of time (3 days or 5 days).

The advantage of this method is that it does not require a great deal of labor. Semi-quantitative assessment can be done by constructing a growth index from slight to copious growth (normally a scale of +, ++, or +++).

3. Explain End-point Methods method of Growth Promotion Tests for Broth Media?

In this method, very low levels of inoculum are added to multiple tubes of the two media under testing. Growth frequency is compared between the two media to understand the equivalency.

4. Explain Most Probable Number (MPN) method of Growth Promotion Tests for Broth Media?

This is a Microbial Limits Test. In this method, the unknown sample is prepared in a ten-fold dilution series and added to nutrient broth in replicate tubes. The tubes will then either turn turbid (growth) or remain clear, and allow for an estimate of the most probable number of microorganisms.

5. Explain Kinetic Parameters method of Growth Promotion Tests for Broth Media?

The growth promoting testing of two lots of broth can be compared by measuring the growth curves of same inocula grown side-by-side. The growth rate of an organism can be determined by spectrophotometrically or by viable count.

6. How Growth Promotion Tests for selective media is performed?

Selective media requires a different approach than general purpose media.  The objective of the test for selective media is to see that the media supports the growth of specific microorganisms. Inhibition, colony morphology and pigment are verified during the testing. In order to determine growth of selective media, specific microorganisms are used as positive or negative indicators.