Survival of Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis Frozen in Skim Milk- Tryptone-Glucose-Glycerol Medium

Abstract
In STGG (skim milk, tryptone, glucose, glycerol) medium at −80°C, Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis isolates survived for at least 3 years, and the same species have survived in nasopharyngeal swabs for at least 1.5 years. At −20°C, S. pneumoniae and M. catarrhalis survived for 1.5 years, but H. influenzae survived for only 2 months.