(Broad Spectrum Aminobenzyl Penicillins)
- More lipid soluble than pen G so more active against Gram (-)
- Better oral absorption (more stable in acid)
- Just as susceptibile to penicillinase
- Hydrolyze in water.
The difference between ampicillin and amoxicillin is that amoxicillin is slightly more lipid soluble than ampicillin. It (may) kill bacteria a little quicker, slightly better more of it is absorbed (and more rapidly). Otherwise, it is essentially the same activity.
Activity Profile (aminopenicillins):
Good as for benzyl Penicillin but also Borrelio, Leptospira, Moraxella
Moderate as for benzyl penicillin and Campylobacter, R. equi, and enterococci
Resistant Constitutive: Bacteroides fragilis, B.
bronchiseptica, Citrobacter, Enterobacter, Klebsiella, other Proteus, P. aeruginosa, Serratia, Y. enterocolitica.Acquired: Actinobacillus, E. coli, P. mirabilis, and Salmonella, and widespread resistant
by Enterobacteriaceae (though they are considered part of the general spectrum).