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Efficacy of ceftriaxone and gentamicin in an abscess model
Abstract:
The therapeutic efficacy of ceftriaxone and gentamicin was investigated in a foreign body induced abscess model in the rat by implanting a dialysis tube contaminated with Klebsiella pneumoniae into the subcutaneous tissue. Animals were treated for four days with ceftriaxone, gentamicin, and their combination starting immediately following or 48 h after the implantation. Peak free ceftriaxone and gentamicin abscess fluid levels were 4.3 and 2.6 mcg/ml, which were 7.3% and 37.5% of peak blood levels respectively. Both agents persisted longer in abscess fluid than in blood. Ceftriaxone inhibited the development of abscess formation when administered shortly after the implantation of the contaminated foreign body whereas gentamicin alone was without beneficial effect. When administered after 48 h ceftriaxone was less effective than immediately after implantation and gentamicin was again without any therapeutic effect. The effect of the combination of ceftriaxone and gentamicin was slightly better than ceftriaxone alone. Low oxygen tension may be an explanation for the lack of bactericidal effect of gentamicin. Ceftriaxone may be more suitable for the therapy of closed space infections caused by susceptible microorganisms than gentamicin.
Insights
Ceftriaxone effectively treated abscesses caused by Klebsiella pneumoniae in rats, especially when given early. Gentamicin showed limited efficacy in this foreign body abscess model.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Abscesses are localized pus collections often caused by bacterial infections.
- Foreign body presence can complicate infection and treatment.
- Klebsiella pneumoniae is a common pathogen in healthcare-associated infections.
Purpose of the Study:
- To evaluate the in vivo efficacy of ceftriaxone and gentamicin against Klebsiella pneumoniae in a rat foreign body abscess model.
- To compare the therapeutic effects of monotherapy versus combination therapy.
- To assess the pharmacokinetic profiles of both antibiotics within abscess fluid.
Main Methods:
- A rat subcutaneous abscess model was created using a dialysis tube contaminated with Klebsiella pneumoniae.
- Animals received ceftriaxone, gentamicin, or combination therapy for four days, initiating treatment immediately or 48 hours post-implantation.
- Antibiotic concentrations in abscess fluid and blood were measured.
Main Results:
- Ceftriaxone significantly inhibited abscess formation when administered early; gentamicin showed no benefit.
- Both antibiotics had longer persistence in abscess fluid compared to blood.
- Combination therapy offered a slight advantage over ceftriaxone monotherapy.
- Delayed treatment (48 hours) reduced ceftriaxone efficacy, while gentamicin remained ineffective.
Conclusions:
- Ceftriaxone demonstrates superior therapeutic efficacy over gentamicin for Klebsiella pneumoniae-induced foreign body abscesses in rats.
- Early administration of ceftriaxone is crucial for optimal treatment outcomes.
- Low oxygen tension in abscesses may contribute to gentamicin's reduced bactericidal activity.
- Ceftriaxone is a potentially more suitable agent for treating closed-space infections caused by susceptible pathogens.