Gram-positive bacteria definition

Amphomycin is mainly active against gram-positive bacteria, with little or no activity against gram-negative bacteria or yeast . As its sodium salt, amphomycin has definite therapeutic effects against experimental Tr. gambiense and Tr. rhodesiense infections in mice and a curative value for fatal avian spirochetosis in chicks . It has successfully protected mice infected by intraperitoneal inoculation with 100 ISD oi Diplococcus pneumoniae ". It has been reported that the antibacterial activity of crystallomycin and amphomycin is lower in the presence of phosphates, but is completely restored after their removal (Table 1.7). 

The mechanism of antibacterial activity is through inhibition of gram-positive bacterial cell-wall synthesis thus, the penicillins are most effective against actively multiplying organisms. Because mammalian cells do not have a definitive cell-wall stmcture as do bacteria, the mammalian toxicity of the penicillins is low. Allergic phenomena in patients following sensitization may occur. 

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