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Comparative activities of ampicillin, epicillin and amoxycillin in vitro and in vivo
Abstract:
The antibacterial activities of three aminopenicillins ampicillin, epicillin and amoxycillin were compared in vitro and in vivo. The minimum inhibitory concentrations (MIC) of the three penicillins were very similar and the compounds were active against non-beta-lactamase-producing strains of Escherichia coli, Salmonella and Shigella species, Proteus mirabilis, Haemophilus influenzae and Neisseria gonorrhoeae. Streptococci including Streptococcus faecalis, and non-beta-lactamase-producing staphylococci were also sensitive to the compounds but Pseudomonas aeruginosa, Klebsiella aerogenes, Enterobacter and indole-positive Proteus species were resistant. At concentrations close to MIC value epicillin and ampicillin showed similar bactericidal activity against E. coli and against S. typhi and both compounds caused a slower rate of kill than was seen with amoxycillin. Microscopical observation of the cells exposed to ampicillin and epicillin for 1 h showed the presence of filamentous forms which lysed slowly, whereas cells exposed to amoxycillin for the same period rapidly. Epicillin was similar to or slightly less active than ampicillin against experimental mouse infections, and against the majority of infections both compounds were significantly less effective than amoxycillin by the oral and subcutaneous routes of administration.
Insights
Ampicillin, epicillin, and amoxycillin show similar antibacterial activity against many bacteria. Amoxycillin demonstrates faster bacterial kill rates and superior efficacy in vivo compared to ampicillin and epicillin.
Area of Science:
- Pharmacology
- Microbiology
- Infectious Diseases
Background:
- Aminopenicillins are crucial antibiotics for treating bacterial infections.
- Understanding the comparative efficacy of different aminopenicillins is vital for optimizing treatment strategies.
Purpose of the Study:
- To compare the in vitro and in vivo antibacterial activities of ampicillin, epicillin, and amoxycillin.
- To evaluate their bactericidal effects and efficacy against various bacterial species.
Main Methods:
- In vitro determination of minimum inhibitory concentrations (MIC) against a panel of bacterial strains.
- In vivo assessment of efficacy in experimental mouse infection models.
- Microscopical examination of bacterial cell morphology following antibiotic exposure.
Main Results:
- Ampicillin, epicillin, and amoxycillin exhibited similar MIC values against susceptible bacteria, including Escherichia coli, Salmonella, Shigella, Proteus mirabilis, Haemophilus influenzae, and Neisseria gonorrhoeae.
- Bacterial resistance was observed against Pseudomonas aeruginosa, Klebsiella aerogenes, Enterobacter, and indole-positive Proteus species.
- Amoxycillin demonstrated a more rapid bactericidal effect against E. coli and S. typhi compared to ampicillin and epicillin.
- In vivo studies indicated amoxycillin was significantly more effective than ampicillin and epicillin via oral and subcutaneous administration.
Conclusions:
- While ampicillin and epicillin share comparable in vitro activity, amoxycillin exhibits superior bactericidal and in vivo efficacy.
- These findings support amoxycillin as a preferred choice for certain bacterial infections due to its enhanced potency and faster action.