622 
Gorbnch 
that such transfer proceeds in ways not discerni- 
ble in the test tube or in artificial laboratory 
conditions. More animal and human feeding ex- 
periments should be performed to confirm the pre- 
vious observations and to provide further assur- 
ance that in vivo transfer of these plasmids would 
not occur. Additional experiments need to be 
designed for study of viral inserts since this rep- 
resents another area of concern. (A special con- 
ference has been convened to deal with the 
problems of viruses and oncogenic gene seg- 
ments.) As an initial step, the participants have 
developed a series of experimental protocols for 
risk assessment experiments. Such experiments 
would evaluate colonization, accpiisition of viru- 
lence, and promiscuous transmission of foreign 
DNA inserts. This process will allow a rational 
evolution of laboratory guidelines for conduct- 
ing recombinant DNA experimentation with E. 
coli K12. 
References 
1. Cooke, E. M. Escherichia coli and man. Churchill Liv- 
ingstone, London. 1971,96 p. 
2. Corbach, S. L. Intestinal microflora. Gastroenterology 
60:1110-1129, 1971. 
3. Smith, H. W. The development of the flora of the ali- 
mentary tract in young animals. }. Pathol. Bac- 
teriol. 90:495-513, 1965. 
4. Gorbach, S. L., Plaut, A. G., Nahas, L., Weinstein, L., 
Spanknebel, G., Levitan. R. Studies of intestinal mi- 
croflora. II. Microorganisms of the small intestine 
and their relations to oral and fecal flora. Gastro- 
enterology 53:856-867, 1967. 
5. Drasar, B. S., Shiner, M., McLeod, G. M. Studies on the 
intestinal flora. I. The bacterial flora of the gastro- 
intestinal tract in healthy and achlorhydric persons. 
Gastroenterology 56:71-79, 1969. 
6. Fincgold, S. M., Attebery, H. R, Sutter, V. L. Effect of 
diet on human fecal flora: comparison of Japanese 
and American diets. Am. J. Clin. Nutr. 27:1456-1469, 
1974. 
7. Moore, W. E. C., Holdeman, L. V. Human fecal flora: 
the normal flora of 20 Japanese-Hawaiians. Appl. 
Microbiol. 27:961-979, 1974. 
8. Savage, D. C. Associations of indigenous microorgan- 
isms with gastrointestinal mucosal epithelia. Am. J. 
Clin. Nutr. 23:1495-1501, 1970. 
9. Plant, A. G., Gorbach, S. L., Nahas, L., Weinstein, L., 
Spanknebel, G.. Levitan, R. Studies of intestinal mi- 
croflora. III. The microbial flora of human small 
intestinal mucosa and fluids. Gastroenterology 53: 
868-873, 1967. 
10. Fretcr, R. Possible effects of foreign DNA on patho- 
genic potential and intestinal proliferation of Es- 
cherichia coli. J. Infect. Dis. 137:624—629, 1978. 
11. GianncIIa, R. A., Broitman, S. A.. Zamcheck, N. Gastric 
acid barrier to ingested microorganisms in man: 
studies in vivo and in vitro. J. Br. Soc. Gastroen- 
terol. 13:251-256, 1972. 
12. Wallick, H., Stuart, C. A. Antigenic relationships of E. 
coli isolated from one individual. J. Bacteriol. 45: 
121-126, 1943. 
13. Winterhalter, R. H.. Turck. M., Pctcrsdorf, R. G. Stud- 
ies on the epidemiology of E. coli infections. V. Fac- 
tors affecting acquisition of specific serological 
groups. J. Clin. Invest. 46:21-29, 1967. 
14. Kauffmann, F., Perch, B. Uber die Coliflora des gesun- 
den Mcnschen. Acta Pathol. Microbiol. Stand. 20: 
201. 1943. 
15. Cooke, E. M., Evvins, S. I’., Shooter. R. A. The chang- 
ing faecal population of E. coli in hospital medical 
patients. Br. Med. J. 4:593-595, 1969. 
16. Cooke, E. M., Shooter, R. A.. Kumar, P. J., Rousseau, 
S. A., Foulkcs, A. Hospital food as a possible source 
of E. coli in patients. Lancet 1:436-4.37, 1970. 
17. Seats. H. I.. Brownlee, I., Uchivama, J. K. Persistence 
of individual strains of E. coli in the intestinal tract 
of man. J. Bacteriol. 59:293-301, 1950. 
18. Seats, H. I.. Brownlee, I. Further observations on the 
persistence of individual strains of E. coli in the in- 
testinal tract of man. J. Bacteriol. 63:47-57, 1952. 
19. Smith, H. W. Transfer of antibiotic resistance from 
animal and human strains of E. coli in the ali- 
mentary tract of man. Lancet 1:1174-1176, 1969. 
20. Formal, S. B., Hornick, R. B. Invasive Escherichia coli. 
J. Infect. Dis. 137:641-644, 1978. 
21. Hctliaratchy, I. G. T. Colicinogeny in E. coli: epidemi- 
ological and other studies related to the establish- 
ment of strains in the human gut. Ph.l). thesis. Uni- 
versity of London, London, 1971. 
22. Smith, H. Microbial surfaces in relation to pathogen- 
icity. Bacteriol. Rev. 41:475-500, 1977. 
23. 0rskov. I.. 0rskov. F.. Jann, B.. Jann, K. Serology, gen- 
etics and chemistry of O and K antigens of Escheri- 
chia coli. Bacteriol. Rev. 41:667-710, 1977. 
24. 0rskov, F. Virulence factors of the bacterial cell sur- 
face. J. Infect. Dis. 137:630-633, 1978. 
25. 0rskov , F., 0rskov, I., Evans, D. J., Jr., Sack, R. B.. Sack, 
D. A., Wadstrom, T. Special Escherichia coli sero- 
types among enterotoxigenic strains from diarrhea 
in adults and children. Med. Microbiol. Immunol. 
162:7.3-80, 1976. 
26. Smith, H. W., Lingood, M. A. Observations on the 
pathogenic properties of the K88, Hly, and ENT 
plasmids of Escherichia coli with particular refer- 
ence to porcine diarrhea. J. Med. Microbiol. 4:467- 
485, 1971. 
27. Evans, D. (... Silver, R. P.. Evans, I). J.. Jr., Chase, D. 
G., Gorbach. S. I.. Plasmid-controlled colonization 
factor associated with virulence in Escherichia coli 
enterotoxigenic for humans. Infec. Immun. 12:656- 
667. 1975. 
28. Schmidt, G. Genelical studies on the lipopolysaccharide 
structure of Escherichia ocli K12. J. Gen. Microbiol. 
77:151-160, 1973. 
29. Gangarosa, E. J. Epidemiology of Escherichia coli in 
the United States. J. Infect. Dis. 137:634-638, 1978. 
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