SECOND REPORT OF THE COGENE WORKING CROUP ON RISK ASSESSMENT 
9 
5. Monitoring of the laboratory work bench, water baths, and centrifuges, 
etc. , occasionally revealed detectable numbers of KK-1 _E . coli K12. Such organ- 
isms could be found immediately after performing laboratory procedures such as 
flaming bacteriological loops, replica plating or transferring cultures (even 
with manual pipetting devices) . Such contamination was instantaneously sterilized 
by simple disinfectants, including 70% ethanol. Deliberate spills of EK-1 K. 
coli K12 had become sterile within six hours after drying. Reliable numberlT'f or 
the survival of EK-2 hosts in the laboratory are not available to us but survival, 
if any, was much reduced relative to ordinary E. coli. 
6. Individuals working with E. coli K12 infected mice and calves were not found 
to more likely become colinized with j£. coli K12 than workers who did only in 
vitro experiments. 
