The preservation of micro-organisms in biological specimens stored at-70 degrees C.
The preservation of micro-organisms that may be found on the skin was studied by storage in liquid media at--70 degrees C. In the first part of the study the performance of 12 varieties of suspending media was evaluated with pure cultures of 17 species of micro-organisms maintained in the laboratory. After storage for 1 year the best medium (Oxoid Nutrient Broth with 15% glycerol) showed a mean survival for all organisms studied of 83.8%, with no significant differences between organisms. Even the worst medium (distilled water) permitted greater than 40% survival at 1 year. No changes in the characteristics of these micro-organisms were detected after 6 months storage in glycerol broth. In the second part of the study nose swabs were suspended in one representative medium (Bacto Nutrient Broth containing 7% glycerol). The mean percentage survival of staphylococci in these suspensions after 1 year's storage at - 70 degrees C was 75.4%. These results indicate that coagulase-negative coagulase-negative staphylococci in samples of skin flora may be stored under these conditions for long periods, greatly reducing the work-load in epidemiological studies of infection.
Ludlam
H A
HA
Division of Microbiology, UMDS, St Thomas' Hospital, London, UK.
Nwachukwu
B
B
Noble
W C
WC
Swan
A V
AV
Phillips
I
I
D015925:Cryopreservation; D003470:Culture Media; D006801:Humans; D009297:Nasal Mucosa / Q000382:microbiology*; D012044:Regression Analysis; D012867:Skin / Q000382:microbiology*; D013210:Staphylococcus / Q000254:growth & development*
D003470:Culture Media