Evaluation Of Different Techniques For Storage And Retrieval Of Microvials Stock Culture

Abstract

Introduction: stocking of bacterial isolates is an integral part of clinical microbiology laboratory as it is used for research work, teaching and quality control purpose. preserving the strains while maintaining it phenotypic and genotypic characters is essential. Therefore, different stocking medias are used to keep them viable.

Aim: To check for the longevity and maintenance of phenotypic and genotypic characters by preserving the isolates in stocking medias like Peptone Glycerol Broth (PGB), Brucella Glycerol Both (BGB) and Skim Milk (SKM).

Materials and Method: this was a prospective analytical study where seven isolates along with three quality control strains were stocked in triplicates with cryobead based peptone broth with 15% glycerol, Brucella Broth (BB) with 15% glycerol and 10% SKM and stored at     -80°C. The stock of each isolate in three different media is then revived at different intervals like monthly, quarterly and at 10th month to check for their viability and phenotypic characters and these are then compared with the readings taken before preservation.

Results: revival rate of PGB, BGB and SKM was 100% and 99% and 90 % respectively when revived monthly. Quarterly revival rate was 100%, 96.60% and 93.30% for PGB, BGB and SKM respectively. Phenotypic characters and antibiotic susceptibility pattern were maintained by all three media after repeated as well as single freeze thaw.

Conclusion: peptone broth with 15% glycerol containing cryobeads can be used as an effective preparation for stock culture maintenance of non-fastidious bacteria and yeast.