Benzylpenicillin potassium has good antibacterial effect on streptococcus, streptococcus pneumoniae and staphylococcus which do not produce penicillin enzyme.It has moderate antibacterial activity against enterococcus.Neisseria gonorrhoeae, neisseria meningitidis, corynebacterium diphtheriae, bacillus anthracis, actinomyces bovis, streptococcus candida, listeria listeriae, leptospira and treponema pallidum are sensitive to this product.This product also has certain antibacterial activity against haemophilus influenzae and bordetella pertussis. Other gram-negative aerobe or facultative anaerobe have poor sensitivity to this product.This product has good antibacterial effect on clostridium, anaerobe of digestive streptococcus and bacillus .