During recent years, erythromycin, which is generally thought to have little antibacterial activity against Gram negative intestinal bacteria in vitro, has been evaluated clinically as a rather effective antibiotic against bacillary dysentery. To clarify the mechanism of the effect of this antibiotic in vivo against bacillary dysentery, we attempted to compare the effect of oral administration of erythromycin upon the intestinal bacterial flora of experimental animals and human children with that of the other antibiotics; colimycin, kanamycin, aminobenzyl penicillin and tetracyclin, which are known to be effective against dysentery bacilli
in vitro.To approach this problems, we examined the antibacterial activities of those antibiotics on nutrient agar, and SS agar, which contained bile acid as an ingredient.
The different behaviour observed between
E. coli and dysentery bacilli to erythromycin on SS agar but not on nutrient agar suggested the importance of specific conditions for a given species of bacteria to conduct antibacterial test
in vitro.
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