Increase in the sensitivity of Shigella to antibiotics

Passages of 10 Shigella strains for 10 times in meat-peptone broth supplemented with sodium nucleinate provided an increase in sensitivity of the cultures to levomycetin for a period of 264 hours. In three strains of S. sonnei, S. flexneri and S. newcastle the authors observed an increase in sensitivity to tetracycline, benzylpenicillin and streptomycin. Some nitrous bases included in sodium nucleinate were also able to increase antibiotic sensitivity in Shigella.