The Journal of Medical Microbiology, Vol 22, Issue 2 157-163, Copyright © 1986 by Society for General Microbiology
Potent antagonism of Escherichia coli, Bacteroides ovatus, Fusobacterium varium, and Enterococcus faecalis, alone or in combination, for enteropathogens in anaerobic continuous flow cultures
T. Ushijima and Y. Ozaki
Interactions between representative strains of four predominant resident
bacteria of the human colon, Escherichia coli, Enterococcus faecalis,
Bacteroides ovatus, and Fusobacterium varium, and strains of seven
enteropathogens, Yersinia enterocolitica, Shigella flexneri, Salmonella
typhimurium, Vibrio parahaemolyticus, V. cholerae serogroup non O1,
Staphylococcus aureus, and Clostridium perfringens, were examined in
studies with an anaerobic continuous flow culture system and medium
resembling the content of the mouse caecum (MCM). Potent unilateral
antagonism attributable to synergic activities of the resident bacteria
against the enteropathogens was evident. The four resident bacteria
persisted at levels of c. 10(6) cfu/ml or more in single and in any mixed
cultures of the resident species. The seven enteropathogens also persisted
in single cultures. In contrast, Y. enterocolitica was excluded in several
days in mixed cultures with each of the four resident bacteria. Sh.
Flexneri and Staph. aureus were excluded in the presence of E. coli alone.
C. perfringens, V. parahaemolyticus and V. cholerae serogroup non O1 were
excluded in the presence of E. coli with B. ovatus and, in some cases, with
additional species. S. typhimurium was the most resistant; only c.
10(2)-fold reduction of the population level was observed in mixed culture
with all four of the resident species. When the amounts of some components
in the medium, such as peptone and yeast extract, were increased, C.
perfringens grew and persisted even in the presence of the four resident
bacteria. Sh. flexneri, in contrast decreased steadily, even in enriched
media.
