Mapping bacterial biofilms on recovered orthopaedic implants by a novel agar candle dip method

Abstract

Dusane DH. Mapping bacterial biofilms on recovered orthopaedic implants by a novel agar candle dip method. APMIS 2019; 127: 123-130.While the detrimental effects of periprosthetic joint infections (PJIs) are well known, the process of biofilm formation on orthopaedic hardware is unclear. Previous work has shown that encasement of explant hardware in agar can aid in identifying biofilms. This study tested the utility of agar 'candle dip' method in detecting and mapping the location of biofilm on infected orthopedic components. Explant components from 15 patients were rinsed, briefly submerged in agar to create a surface coating, and incubated. Larger components were coated by pipetting agar over them. After incubation, colony outgrowth on the component surface was documented (candle dip status). Data were compared with clinical laboratory results (clinical culture status) and the PJI diagnosis using Musculoskeletal Infection Society criteria (MSIS status). All six patients classified as MSIS and clinical culture positive were also positive with the candle dip technique. Of the nine candle dip negative cases, four were positive and five were negative for both MSIS and clinical culture status. Candle dip may be negative in few cases due to the residual antibiotic eluting from the spacers, limiting the growth of bacterial biofilms on the components. The candle dip method shows promise for biofilm mapping but requires additional testing to evaluate the clinical diagnostic potential.

<i>Pseudomonas aeruginosa</i> biofilm killing beyond the spacer by antibiotic-loaded calcium sulfate beads: an in vitro study

“…4a-d) and illustrates the importance of adequate spatial coverage within a periprosthetic joint or other infected surgical sites. Nevertheless, our in vitro data as well as those found clinically (Morgenstern et al, 2018;Ciofu et al, 2017), and data from other in vitro studies (Howlin et al, 2015(Howlin et al, , 2017Laycock et al, 2018;Knecht et al, 2018) support the use of ALCS-B as an effective means of releasing antibiotic to prevent biofilm spread and kill pre-grown bacterial biofilms.…”

Implant surface culture may be a useful adjunct to standard tissue sampling culture for identification of pathogens accounting for fracture-device-related infection: a within-person randomized agreement study of 42 patients

“…The satisfying outcome of the aforementioned “agar candle dip” method ( 9 ) implies that culture on explant components may be a useful strategy to identify FDRI-related pathogens because of the possibility of bacterial biofilms attached to the implant surfaces. We believe that ISC primarily has 3 advantages compared with TSC.…”

“…Recently, a study reported using a novel “agar candle dip” method to map the bacterial biofilms on recovered orthopedic implants ( 9 ), which showed promise in growing bacteria directly from the implants. These findings suggest that culturing directly from implant surfaces may be an effective method for bacteria detection as there may exist bacterial biofilms attached to the implant surfaces.…”

Current and novel diagnostics for orthopedic implant biofilm infections: a review

“…The implant must then be submerged in cooled agar and placed in a new container to be incubated for 7 days. In this study, the agar began to noticeably dry out after a 24‐h incubation period; therefore, the authors incorporated an agar replenishment step every 24 h for 7 days in their methodology [58].…”

“…This method can have a lot of colony growth in the growth media. Also, research with a larger quantity of patient samples is necessary prior to clinical use [58].…”