Chapter 15, Problem 1CT

Summary Introduction

To explain:

The reason that the specimens should be taken aseptically and processed quickly to ensure accurate results, even when non-sterile sites are being sampled and selective media are to be used.

Concept introduction:

Growth of microorganisms takes place in culture medium containing agar. This medium contains tryptone, yeast extract and sodium chloride at pH value equal to 7.0. Selective medium grows specific strains of bacteria without growth of unwanted strains of bacteria in the culture medium. Antibiotics are added which prevents the growth of unwanted bacteria.

Explanation of Solution

Aseptic growth requires that agar plates should be sterilized and autoclaved at high pressure and temperature. The chance and probability of infection is less and specific growth of required strain of bacteria takes place containing antibiotic resistance. Specific salts are added for growth of microorganisms with specific growth requirements. Ethanol is used for sterilization the environment near the plates which prevents the growth of microorganisms which can contaminate the plate. Antibiotic testing is required for the growth of specific strains of bacteria which prevents the growth of unwanted strains which are sensitive to antibiotics.

Conclusion

Aseptic conditions require the growth of specific strains of bacteria with antibiotic resistance which prevents the growth of unwanted strains of bacteria in the selective culture medium. Ethanol sterilization can be done to prevent the growth of unwanted strains of bacteria.