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Activity of amikacin, gentamicin and kanamycin against Pseudomonas aeruginosa
Abstract:
The activity of amikacin, gentamicin and kanamycin was tested in vitro against clinical isolates of Pseudomonas aeruginosa. Concentrations of the antibiotics in serum and in saline solution were prepared according to serum levels produced in volunteers 15 minutes, 1,2, and 6 hours after a single intramuscular injection of 500 mg amikacin, 80 mg gentamicin and 500 mg kanamycin. Following isolation of the Pseudomonas strains in cultures, they were incubated and seeded in Mueller-Hinton broth, then 10(-7) dilutions of the organisms were kept in contact with the prepared antibiotic solutions in serum and in saline solution for three hours, the approximate half-life of the antibiotics in serum. Amikacin was active at concentrations seen six hours post-dose, inhibiting growth in a total of 72-5% of seeded plates. Gentamicin was active for only two hours and inhibited growth in 2-5% of the plates. Kanamycin showed no antipseudomonal activity.
Insights
Amikacin demonstrated significant in vitro activity against Pseudomonas aeruginosa, remaining effective for six hours post-injection. Gentamicin showed limited efficacy, while kanamycin was ineffective. This highlights amikacin
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is a significant opportunistic pathogen.
- Aminoglycoside antibiotics are crucial for treating P. aeruginosa infections.
- Understanding antibiotic efficacy at various concentrations is vital for treatment optimization.
Purpose of the Study:
- To evaluate the in vitro activity of amikacin, gentamicin, and kanamycin against clinical isolates of Pseudomonas aeruginosa.
- To determine the duration of antibiotic activity in serum and saline based on achievable post-injection concentrations.
Main Methods:
- Clinical isolates of P. aeruginosa were cultured and prepared in Mueller-Hinton broth.
- Antibiotic solutions (amikacin, gentamicin, kanamycin) were prepared simulating serum levels at 15 minutes, 1, 2, and 6 hours post-intramuscular injection.
- Organisms were incubated with antibiotic solutions for three hours (approximate serum half-life).
- Inhibition of bacterial growth was assessed on seeded plates.
Main Results:
- Amikacin exhibited activity at concentrations found six hours post-dose, inhibiting growth in 72.5% of plates.
- Gentamicin demonstrated activity for only two hours, inhibiting growth in 2.5% of plates.
- Kanamycin showed no significant antipseudomonal activity in vitro.
Conclusions:
- Amikacin possesses sustained in vitro activity against P. aeruginosa at clinically relevant concentrations.
- Gentamicin has a shorter duration of efficacy compared to amikacin.
- Kanamycin is not effective against P. aeruginosa based on this study.