9 
and cxchiinye planmids 
CO li . 
bacteria could multiply in laryc; nuinboru 
v/ith other more ubiquitous strains o-f E. 
(2) Genetic exchange of plasmids in E. col i is well 
knov/n , both between strains of E. coli as well as with Shigella 
and S a 1 raone 11a . Thus, v;hile a K-12 strain containing a recomb iniin t 
DNA plasmid, fiven one constructed so as to greatly reduce as 
chances of survival in nature (EK2 or EK3) , could donate its 
plasmid to one of the approximately 150 serotypes of E. co_lJ^ 
found in the gastrointestinal tracts of miost humans, most of 
which are capable of accepting plasmids. Survival per se is 
not the issue. Genetic exchange is. 
(3) E. coli has, over the past eight years, emerged as 
1/2/3/ 
one of the primary causes of gastroenteritis and diarrhea 
The disease can be produced by any of several strains of E. coli 
containing a plasmid which carries the genes for one of two toxins 
(or both) , one of which resembles cholera toxin, plus the genes 
for a surface factor required for colonization of the small bowel, 
also carried by a plasmid. 
(4) E. coli is responsib]e for nearly 100% of upper urinary 
tract infections, including severe cases where the kidneys are 
1 / 
involved, and most cases of cystitis. This type of infection 
is independent of the capacity of E. coli to colonize the human 
gut. 
1/ 
R. 
W. 
Ryder 
, et 
al. , 
New England J. 
Med., 295, 
859-853 (1976) 
2/ 
R. 
B. 
Sack , 
NcV7 
):]ngl( 
an d J . Me d . , 2 9 
5, 893-894 
(1976) . 
V 
B. 
D. 
Da vi s 
, cj. 
ill.- <• 
Microbiology , 
768 (2nd Ed 
. , 1973). 
Appendix K — 63 
