Spectrum: Ampicillin is broad-spectrum, effective against both Gram-positive and Gram-negative bacteria including Gram-negative non-extended spectrum β-lactamase (ESBL) bacteria including Staphylococcus and Streptococcus species and medically important enteric pathogens such as Shigella and Salmonella. Interestingly, Ampicillin has been found to be effective against certain β-lactam sensitive vancomycin-resistant Enterococcus (VRE); a glycopeptide antibiotic resistant 'superbug'. Resistance to Ampicillin is routinely used as a selectable marker to confirm successful cell transformation
Mechanism of Action: Like all β-lactams, Ampicillin interferes with penicillin binding protein (PBP) activity, otherwise involved in the final phase of peptidoglycan synthesis. PBPs are enzymes which catalyze a pentaglycine crosslink between alanine and lysine residues. Without a pentaglycine crosslink, the integrity of the cell wall is severely compromised ultimately leading to cell lysis
