Final answer:
Bacitracin is a peptide antibiotic effective against gram-positive bacteria, it works by inhibiting the dephosphorylation of lipid pyrophosphate, which is vital for cell wall synthesis in bacteria.
Step-by-step explanation:
The peptide antibiotic that is effective against gram-positive bacteria and inhibits bacterial cell wall synthesis by inhibiting dephosphorylation of lipid pyrophosphate is Bacitracin. This mode of action prevents peptidoglycan precursors' movement, crucial for bacterial cell wall synthesis. The action of bacitracin results in a bactericidal effect since it disrupts the integrity of the bacterial cell wall, which is essential for bacterial survival and replication. Unlike antibiotics like polymyxin B, which target gram-negative bacteria by disrupting their outer and inner membranes, bacitracin specifically inhibits the building of the bacterial cell wall in gram-positive organisms. The selective toxicity is possible because human cells do not contain peptidoglycan, the substance bacitracin targets. This narrow target range prevents damage to human cells while effectively combating bacterial pathogens.