EComment. The devil is in the detail!

Abstract

I read with great interest the quasi-experimental single-centre prospective cohort study conducted by Birgand et al. [1] evaluating the efficacy of a gentamicin-collagen sponge in decreasing deep sternal-wound infections in high-risk cardiac surgery patients. Interstingly, in their experience gentamicin-collagen sponge was not effective in preventing deep sternal wound infections in high-risk patients. This is contrary to our own experience [2] and the most plausible explanation for the conflicting results lies in the technique of using the gentamicin-collagen sponge. Birgand and associates dipped the sponge in normal saline solution for a few seconds prior to implantation [1]. This manoeuvre of wetting the gentamicin-collagen sponge impacts on the gentamicin content of the implant and affects its potential antibacterial efficacy. Lovering and colleague [3] have recently shown that that even a short period of dipping of gentamicin-collagen sponge, before insertion into the patient, results in a significant loss of gentamicin which may be of clinical significance. They demonstrated that after a very short immersion period there was significant loss of gentamicin from the implants with a mean loss of 6.7% at 2 s, increasing to 40.5% at 1 min and essentially total loss by 6 h of immersion. Loss of gentamicin followed a complex elution profile, with elution half-lives ranging from 50 s on initial immersion to 99 min late in the elution period. It is very clear from the study of Lovering et al. [3] as well as from our own experience [2] that attention to detail will possibly result in different outcomes thereby minimising studies with conflicting results. Conflict of interest: none declared