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Comparative activity of amoxycillin and ampicillin in an experimental bacterial infection in mice
Abstract:
Against experimental infections in mice with strains of Escherichia coli and with Proteus mirabilis, amoxycillin was found to be more active than ampicillin both by the oral and the subcutaneous routes of administration. With the bacteria used in these experiments, ampicillin and amoxycillin showed the same minimal inhibitory concentrations and, after subcutaneous administration, the levels of ampicillin and amoxycillin in the plasma and tissue homogenate were also similar. However, counts of the number of viable bacteria present in the infected tissue showed that amoxycillin exerted a more rapid and a more marked bactericidal effect than did ampicillin, and this could be correlated with the difference in therapeutic effect. When given by mouth, amoxycillin was more completely absorbed than ampicillin and gave rise to higher levels of antibiotic in the plasma. This may have accounted in part for the difference in therapeutic activity seen when these penicillins were given by the oral route. However, when appropriate oral dosages of ampicillin and amoxycillin were used so as to achieve similar levels of antibiotic in the plasma and tissue homogenate, amoxycillin was again found to exert a more marked bactericidal effect than did ampicillin, and this was accompanied by greater therapeutic activity. In experiments in vitro, amoxycillin also showed a more rapid bactericidal effect than did ampicillin against the bacteria which were used to produce the experimental infections.
Insights
Amoxycillin demonstrates superior therapeutic activity compared to ampicillin in treating experimental bacterial infections in mice. This enhanced efficacy is linked to amoxycillin's more rapid and potent bactericidal effect.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Antibiotics like ampicillin and amoxycillin are crucial for treating bacterial infections.
- Understanding comparative efficacy is vital for optimal therapeutic strategies.
Purpose of the Study:
- To compare the in vivo and in vitro efficacy of amoxycillin and ampicillin against Escherichia coli and Proteus mirabilis.
- To investigate the pharmacokinetic and pharmacodynamic differences influencing their therapeutic activity.
Main Methods:
- Experimental infections in mice with E. coli and P. mirabilis.
- Administration via oral and subcutaneous routes.
- Measurement of minimal inhibitory concentrations, plasma and tissue antibiotic levels, viable bacterial counts, and therapeutic outcomes.
Main Results:
- Amoxycillin exhibited greater therapeutic activity than ampicillin via both administration routes.
- Despite similar minimal inhibitory concentrations and tissue levels, amoxycillin showed a more rapid and pronounced bactericidal effect.
- Oral amoxycillin was better absorbed, achieving higher plasma levels than ampicillin.
Conclusions:
- Amoxycillin possesses a more potent bactericidal effect than ampicillin, contributing to its superior therapeutic performance.
- Enhanced absorption and bactericidal activity underpin amoxycillin's improved efficacy in treating experimental bacterial infections.