Viability assessment of <i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Abony NCTC 6017 in ampoules and vials by the accelerated shelf-life testing method

Abstract

INTRODUCTION. A key priority in maintaining a collection of microorganisms is to ensure the stability of characteristics and the viability of microbial cultures during their storage and transport. In addition, some applications of collection strains as control samples require accurate data on the number of viable microbial cells in each sample. Therefore, it is necessary to develop and implement an analytical procedure for predicting the guaranteed shelf life of test strains.AIM. This study aimed to predict the guaranteed shelf life for test strains in a variety of primary packaging by assessing changes in microbial viability under accelerated storage conditions, with the Salmonella enterica subsp. enterica serovar Abony NCTC 6017 strain as a model organism.MATERIALS AND METHODS. The study used lyophilised samples of the S. enterica subsp. enterica serovar Abony NCTC 6017 strain deposited in the National Collection of Pathogenic Microorganisms (NCPM) at the Scientific Centre for Expert Evaluation of Medicinal Products of the Ministry of Health of the Russian Federation. The studied primary packaging types included vacuum-filled borosilicate glass ampoules and 2R lyophilisation vials. The samples were tested for a number of quality attributes (loss on drying, viable cell count, cell viability, colony morphology, and biochemical identification) and subjected to accelerated shelf-life testing at ele­vated temperatures (35–65 °С).RESULTS. The study did not show any significant differences in the quality of lyophilised samples depending on the type of primary packaging. The authors experimentally determined rate constants for the loss of viability in microbial cultures during storage at elevated temperatures and calculated the rate constants for the storage and transport temperatures and for different types of primary packaging. The predicted time to viable cell count reduction to 10% of the initial level was 19 years for vials and 25 years for ampoules, and the predicted time to 50% viability was 5.8 years for vials and 7.6 years for ampoules.CONCLUSIONS. The results of this study confirm the applicability of different primary packaging (ampoules and vials) for the lyophilisation and storage of microbial test strains. The data obtained can guide further research and contribute to the development of recommendations for the storage of lyophilised strains in various types of packaging.