Related Experiment Videos
Penicillin-netilmicin synergism against Streptococcus faecalis
Abstract:
The combination of penicillin plus netilmicin was synergistic in vitro against 28 strains of Streptococcus faecalis and compared favorably with penicillin in combination with gentamicin. Similarly, penicillin plus netilmicin was as effective as penicillin plus gentamicin in the therapy of 67 rabbits with enterococcal endocarditis produced with a streptomycin-susceptible (S) or a streptomycin-resistant (R) strain of S. faecalis. After 5 days of infection, control rabbits had bacterial titers of 10(10) colony-forming units (CFU)/g of vegetation. Those treated with penicillin plus netilmicin had mean titers of 10(5.2) and 10(5.1) CFU/g for S and R strains, respectively, and those treated with penicillin plus gentamicin had mean valve titers of 10(5.8) CFU/g for both strains. After 10 days of therapy, mean valve titers with penicillin plus netilmicin were 10(3.8) and 10(4.7) CFU/g, and with penicillin plus gentamicin they were 10(4.5) and 10(5.4) CFU/g for S and R strains, respectively. Thus, if netilmicin proves to be less toxic than other aminoglycoside antibiotics, it may have potential usefulness in the therapy of enterococcal endocarditis.
Insights
Penicillin plus netilmicin showed synergistic effects against Streptococcus faecalis in vitro and effectively treated enterococcal endocarditis in rabbits. This combination may offer a valuable therapeutic option for enterococcal endocarditis.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Enterococcal endocarditis is a serious infection.
- Aminoglycoside antibiotics are often used in combination therapy.
- Netilmicin is an aminoglycoside antibiotic with potential therapeutic applications.
Purpose of the Study:
- To evaluate the in vitro synergy of penicillin plus netilmicin against Streptococcus faecalis.
- To compare the efficacy of penicillin plus netilmicin with penicillin plus gentamicin in a rabbit model of enterococcal endocarditis.
Main Methods:
- In vitro susceptibility testing of 28 Streptococcus faecalis strains against penicillin and netilmicin.
- Experimental enterococcal endocarditis induced in 67 rabbits using streptomycin-susceptible or -resistant strains of S. faecalis.
- Treatment with penicillin plus netilmicin or penicillin plus gentamicin, with bacterial titers assessed in vegetations.
Main Results:
- Penicillin plus netilmicin demonstrated synergistic activity in vitro and was comparable to penicillin plus gentamicin in reducing bacterial titers in rabbit endocarditis models.
- After 10 days of therapy, penicillin plus netilmicin achieved lower mean valve titers than penicillin plus gentamicin for both streptomycin-susceptible and -resistant strains.
Conclusions:
- Penicillin plus netilmicin is effective in treating experimental enterococcal endocarditis.
- Netilmicin may be a useful alternative to gentamicin in combination therapy for enterococcal endocarditis, pending further toxicity studies.