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Morphologic changes produced by amdinocillin alone and in combination with beta-lactam antibiotics: in vitro and in
Abstract:
Scanning electron microscopy was used to study the morphologic effects of amdinocillin (mecillinam) when combined with several beta-lactam antibiotics in vitro (Escherichia coli, three isolates; Klebsiella pneumoniae, one isolate) and also in vivo (E. coli, one isolate). Ovoid forms were found in the cultures of E. coli and K. pneumoniae following in vitro exposure to amdinocillin. This characteristic in vitro effect was also produced in the amdinocillin-treated E. coli-infected mouse. Varying degrees of filament formation were seen both in vitro and in vivo with the other beta-lactam antibiotics tested. The in vitro combination of amdinocillin with the beta-lactam antibiotics produced morphologic effects on E. coli and K. pneumoniae (enhanced cell distortion and lysis) not seen with the individual agents at the doses tested. Amdinocillin was synergistic with ampicillin, carbenicillin, and cephalothin in mice challenged with E. coli 736; scanning electron microscopy of bacteria from peritoneal lavages of mice treated with these synergistic combinations indicated that the organisms were more enlarged and distorted than those from animals receiving the individual agents. The enhanced morphologic effect observed in vivo was in agreement with the in vitro effect. Viable counts of bacteria recovered from mice treated with ampicillin plus amdinocillin were appreciably less than those from mice treated with each agent alone. The morphologic results from the scanning electron microscopy study point to a synergistic or enhanced effect of amdinocillin in combination with beta-lactam antibiotics and are in accord with prior reports of the synergistic effects of amdinocillin.
Insights
Amdinocillin combined with other beta-lactam antibiotics shows enhanced antibacterial effects. Scanning electron microscopy revealed synergistic morphologic changes in bacteria, indicating improved treatment efficacy.
Area of Science:
- Microbiology
- Pharmacology
- Electron Microscopy
Background:
- Amdinocillin (mecillinam) is a beta-lactam antibiotic.
- Beta-lactam antibiotics are crucial in treating bacterial infections.
- Understanding synergistic antibiotic effects is key to optimizing treatment.
Purpose of the Study:
- To investigate the morphologic effects of amdinocillin in combination with other beta-lactam antibiotics.
- To evaluate the synergistic activity of amdinocillin in vitro and in vivo.
- To correlate morphologic changes with antibacterial efficacy.
Main Methods:
- Scanning electron microscopy (SEM) was employed to visualize bacterial morphology.
- Experiments were conducted both in vitro using bacterial cultures and in vivo using infected mice.
- Bacterial isolates included Escherichia coli and Klebsiella pneumoniae.
Main Results:
- Amdinocillin alone induced ovoid forms in E. coli and K. pneumoniae.
- Combinations of amdinocillin with ampicillin, carbenicillin, and cephalothin showed enhanced cell distortion and lysis.
- In vivo studies demonstrated synergistic effects, with more enlarged and distorted bacteria observed in combination treatments.
Conclusions:
- Amdinocillin exhibits synergistic effects when combined with certain beta-lactam antibiotics.
- SEM reveals enhanced morphologic damage to bacteria under combination therapy.
- These findings support the use of amdinocillin in combination regimens for improved antibacterial activity.