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Penicillin-induced effects on streptomycin uptake and early bactericidal activity differ in viridans group and
Abstract:
In vitro studies with penicillin and [3H]streptomycin in four strains of streptococci (S. faecalis, S. sanguis, and S. mitis) were performed by simultaneously measuring the rates of bacterial killing and uptake of streptomycin. In S. faecalis, penicillin stimulated streptomycin uptake, as has been shown by Moellering and Weinberg (R. C. Moellering, Jr., and A. N. Weinberg, J. Clin. Invest. 50:2580-2584, 1971). Moreover, the antibiotic combination was associated with an enhanced bactericidal rate which temporally correlated with beta-lactam-induced aminoglycoside uptake. In contrast, in viridans group streptococci (S. sanguis and S. mitis) penicillin had no effect on streptomycin uptake and a minimal effect on bactericidal rate when compared with either drug alone. These data suggested that the stimulation of streptomycin uptake in streptococci by penicillin is strain or species specific and that important differences exist between enterococci and viridans group streptococci regarding the mechanisms of beta-lactam-aminoglycoside potentiation.
Insights
Penicillin enhances streptomycin uptake and bacterial killing in *Streptococcus faecalis* but not viridans group streptococci. This suggests strain-specific mechanisms for beta-lactam-aminoglycoside potentiation.
Area of Science:
- Microbiology
- Pharmacology
- Bacterial Genetics
Background:
- Antibiotic resistance is a growing concern.
- Beta-lactam antibiotics and aminoglycosides are commonly used antimicrobial agents.
- Synergistic effects between different antibiotic classes can improve treatment outcomes.
Purpose of the Study:
- To investigate the in vitro interaction between penicillin and streptomycin in different streptococcal strains.
- To determine if penicillin enhances streptomycin uptake and bactericidal activity in *Streptococcus faecalis* and viridans group streptococci (*S. sanguis*, *S. mitis*).
- To explore potential differences in the mechanisms of beta-lactam-aminoglycoside potentiation between enterococci and viridans streptococci.
Main Methods:
- In vitro studies using four strains of streptococci.
- Simultaneous measurement of bacterial killing rates and streptomycin uptake.
- Treatment with penicillin, streptomycin, or the combination.
Main Results:
- Penicillin significantly stimulated streptomycin uptake and enhanced the bactericidal rate in *Streptococcus faecalis*.
- This potentiation correlated with beta-lactam-induced aminoglycoside uptake.
- In contrast, penicillin had minimal effect on streptomycin uptake and bactericidal activity in viridans group streptococci (*S. sanguis*, *S. mitis*).
Conclusions:
- The stimulation of streptomycin uptake by penicillin in streptococci is strain and species-specific.
- Significant differences exist in the potentiation mechanisms between enterococci and viridans group streptococci.
- Understanding these differences is crucial for optimizing combination antibiotic therapy.