An evaluation of the shelf life of ceftriaxone–polymethylmethacrylate antibiotic beads

Abstract

Background

In a resource poor country like ours, left-over ceftriaxone-impregnated beads produced intraoperatively for treating chronic osteomyelitis need not be wasted. The possibility of keeping them on the shelf for use for indigent patients and also in the treatment of open fractures that often present late in our environment was considered. Thus, it became necessary to evaluate the shelf life of these antibiotic beads when stored as dry or wet beads at tropical room temperature.

Methods

Dry and wet ceftriaxone–polymethylmethacrylate (PMMA) antibiotic beads produced at a ratio of 1:20 using the Alonge–Wale intraoperative antibiotic bead maker were placed in agar plates containing pure cultures of Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella species and Escherichia coli that were propagated in brain–heart infusion broth. Zones of inhibition or peribeadal lysis were measured at 6 and 12 weeks, 3, 6 and 12 months, respectively.

Results

At 12 months (from the date of production of the beads), the dry beads at tropical room temperature continued to elute significant quantity of ceftriaxone against all the microorganisms cultured in this study. In contrast, the elution from the wet beads (soaked in sterile phosphate-buffered saline) diminished remarkably after 6 weeks.

Conclusions

This study shows that ceftriaxone–PMMA beads when dry-stored for up to 12 months at tropical room temperature continue to elute inhibitory concentrations of ceftriaxone. The ceftriaxone–PMMA beads can, therefore, be available ‘off the shelf’ at least for 12 months after preparation.