Document Detail

Bacterial kill rates of amoxycillin and ampicillin at exponentially diminishing concentrations simulating in vivo conditions.
MedLine Citation:
PMID:  6995345     Owner:  NLM     Status:  MEDLINE    
The responses of bacteria exposed to amoxycillin and ampicillin were studied at continuously decreasing levels with half-life values similar to those which could occur in vivo. For Escherichia coli, the kill-rates were higher with amoxycillin than with ampicillin. The bactericidal response was exponential. With an antibiotic half-life of one hour, the amoxycillin first order inactivation rate was 3.544 h-1 and the viable cell half-life was 0.196 h; the respective values for ampicillin were 2.341 h-1 and 0.296 h. With an antibiotic half-life of five hours, the inactivation rate was 0.704 h-1 corresponding to a viable cell half-life of 0.985 h for amoxycillin compared to 0.358 h-1 and 1.937 h respectively for ampicillin. Comparison of viable counts and photometric monitoring showed that the former is the preferable method for recording the bacterial response to these beta-lactam antibiotics. During the phase of exponential kill, a plateau occurred in the optical density values. This was due in part to an increased biomass per cell. During the recovery phase, the number of viable cells started to increase several hours sooner than did the rise in optical density. For Staphylococcus aureus,the rates of kill were similar with both agents. Amoxycillin had a long bacteriostatic phase which was not seen with ampicillin. This led to a longer lasting antibacterial effect and reduction to a lower total count with amoxycillin. With staphylococci, the viable counts and the photometric responses were parallel.
T Bergan; I B Carlsen
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Infection     Volume:  Suppl 1     ISSN:  0300-8126     ISO Abbreviation:  Infection     Publication Date:  1980  
Date Detail:
Created Date:  1980-10-27     Completed Date:  1980-10-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0365307     Medline TA:  Infection     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  103-8     Citation Subset:  IM    
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MeSH Terms
Amoxicillin / pharmacology*
Ampicillin / pharmacology*
Dose-Response Relationship, Drug
Escherichia coli / drug effects*
Microbial Sensitivity Tests
Staphylococcus aureus / drug effects*
Time Factors
Reg. No./Substance:
26787-78-0/Amoxicillin; 69-53-4/Ampicillin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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