Cross Resistance to Antibiotics

Abstract

Summary and Conclusions

The antibacterial spectrum of carbomycin parallels very closely that of erythromycin. Both of these new antibiotics are highly active against gram-positive and gram-negative cocci, moderately active against strains of Haemophilus and are essentially inactive against coliform and enteric bacilli. Against susceptible bacterial strains erythromycin is usually from 4 to 16 times more active than carbomycin, weight for weight. Repeated subcultures of staphylococci and of certain strains of streptococci in the presence of increasing concentrations of either one of these antibiotics result in fairly rapid and marked increases in resistance not only to the antibiotic to which it was exposed but to the other agent as well.