Question

why isn’t gene sequencing and genomic sequencing normally used to identify pathogens?

Why can antibody testing of patient serum be inaccurate?

What does MacConkey agar detect?

How is gelatinase tested for?

How is a positive gelatinase test determined?

How is the oxidase test performed?

Answer 1

1 Ans: Gene sequencing is not directly used for pathogen detection as their DNA contains about 6-14 % of the non-coding region. To counter this problem, RNA is isolated from microbes and then RNA is converted to cDNA using the PCR technique. This cDNA sequencing could be performed or RT-PCR could be performed to identify the pathogen.

Also, main challenge associated with genome sequencing is de novo assembly of the genome.

2 Ans: When a person gets infected, immune cells release antibodies to neutralize ingectious antigen. But sometime, antibody testing of patient serum can be inaccurate when infcetion is in primary stage or not enough antibodies have been build in body that can be detected.

3 Ans: MacConkey agar identify and differentiate enteric bacteria based on their capacity of lactose fermentation. The growth of gram-positive bacteria is inhibited due to the presence of bile salt and crystal violet. The agar rurns red or pink in color in presence of lactose fermenting bacteria (positive result).

4 Ans: Nutrient gelatin medium is used to test gelatinase. Gelatin of medium is hydrolyzed and liquidified in presence of gelatinase enzyme produced by microorganism.