Comparison different methods of long-term maintenance and survival of Streptococcus pneumoniae isolates

One of the major problems for the isolation and detection of S. pneumoniae from clinical specimens, high sensitivity, rapid autolysis and thus the inability to hold isolates of pneumococcus. So, it is essential to use specific techniques for the preservation of the organism. In this study several different cultures for S. pneumoniae isolates were compared and evaluated.
In 2014, 2 ATCC standard , 30 clinical, and 30 normal flora pneumococcal available isolates were selected from a previous study. Dorset egg medium was prepared for midterm preservation, three storage environments, including Skim milk-Tryptone-Glucose-Glycerin (STGG), nutrient broth enriched and Todd Hewitt Broth (THB) was constructed to long-term preservation, and their performance on maintenance pneumococcal isolates was assessed.
Results and 95% of the isolates cultured on Dorset after 70 days and 80% after four months later had the ability to grow. All three long-term storage environment, had a good performance for one year but enriched nutrient broth could keep bacteria with but better-quality up to 2 years. There is no difference between isolates from the patients and isolates from normal flora to survive in the environment. Also aggressive origin of iclinical isolates had no effect on their survival rate. Dorset egg (DE) medium can be considered as a simple, low cost and efficient, medium for midterm preservation and enriched nutrient broth for long term storage of pneumococcal isolates in clinical laboratories.