Antimicrobial-Loaded Bone Cement Does Not Negatively Influence Sonicate Fluid Culture Positivity for Diagnosis of Prosthetic Joint Infection

Abstract

We compared culture results to investigate the influence of antimicrobial-loaded cement on sonicate fluid culture positivity for the diagnosis of prosthetic joint infection. Fifty-four subjects were assessed. The sensitivities of sonicate fluid culture were 77.8% (14 of 18) in subjects with an antimicrobial-loaded cemented prosthesis and 58.3% (21 of 36) in subjects with an antimicrobialfree prosthesis. With the increasing number of lower-extremity total joint arthroplasty surgeries, there has been an increase in the number of prosthetic joint infections (PJIs) (1). Organisms associated with PJI attach to the implant, polymethylmethacrylate (PMMA), and/or bone surfaces, where they grow in biofilms. Antimicrobialloaded PMMA is used in the prevention and treatment of PJI (2, 3). We previously reported that culture of fluid obtained by sonication of removed implants is more sensitive than culture of conventional periprosthetic tissue for the diagnosis of PJI (4). Previous antimicrobial exposure has been reported to have a negative effect on microbiologic diagnosis (4, 5). Moreover, it has been shown that in vitro application of pulsed ultrasound leads to increased release of gentamicin from antimicrobial-loaded bone cement (6). Therefore, the aim of this study was to determine, by using a retrospective review of clinical cases, whether antimicrobial-loaded PMMA influences sonicate fluid culture positivity.PJI was diagnosed using Infectious Diseases Society of America guidelines if at least one of the following was present: a sinus tract communicating with the prosthesis, purulence noted at the time of surgery, or acute inflammation detected on intraoperative frozen section histology (7). Patients with removal of spacers during the two-stage exchange process or subjects who were Ͻ18 years old as well as those with the criteria noted below were excluded. Between April 2006 and August 2015, 362 patients with confirmed PJI undergoing removal of a total knee or hip prosthesis at Mayo Clinic, Rochester, Minnesota, were enrolled; 227 were excluded because they had received antimicrobial therapy within 4 weeks before the collection of the implant for culture, 80 were excluded because of insufficient medical record information, and one who had a Mycobacterium chelonae infection was excluded. A total of 54 patients were enrolled, and all had undergone removal of a single prosthesis.Tissue culture was performed on 2 to 7 periprosthetic tissue specimens per patient. Implants were cultured according to a previously described protocol, which included sonication, vortexing, and concentration (8). Briefly, the container was vortexed for 30 s and subjected to sonication (40 kHz and 320 mW/cm 2 for 5 min). Sonicate fluid culture positivity was determined according to a previously described method (8). The Mann-Whitney U test was used to compare the continuous variables, and the 2 test was used to compare the categorical variables. All P values were two tailed, and a P value of Ͻ0.05 was considered statistically significant. The sens...

Biofilm prevention of gram-negative bacterial pathogens involved in periprosthetic infection by antibiotic-loaded calcium sulfate beads in vitro

“…We previously demonstrated the in vitro efficacy of PG-CSH beads loaded with a broad-spectrum antibiotic combination of vancomycin and tobramycin in combination against key gram-positive organisms associated with PIs [19]. The incorporation of tobramycin in combination with vancomycin permits broad spectrum activity against gram-negative pathogens as well and is frequently used in eluting acrylic and mineral cements for dead space management or mechanical function [30][31][32][33][34][35]. Given the increased risk of failure and reduced success rate for therapeutic intervention associated with gram-negative pathogens in PIs, we evaluated this antibiotic combination loaded into PG-CSH beads against K. pneumoniae, A. baumannii and P. aeruginosa biofilm formation and established biofilms in order to better characterise the in vitro antibacterial and antibiofilm efficacy of PG-CSH beads [20,22].…”

Sonication Culture of Antimicrobial Agent-Containing Cement Spacers Removed during Staged Revisions for Arthroplasty Infection

“…However, the amount of fluid used for sonication of the ACSs was not measured, and patients were also receiving systemic antibiotics at the time of explantation of the ACS, factors that could additionally or alternatively affect culture results. On the other hand, a study performed by our group showed that antimicrobialloaded cement used for the fixation of the prosthesis did not negatively impact sonicate fluid culture of the explanted prostheses (27). It is possible that even if sonication increases the release of antimicrobials from ACSs, the lactated Ringer's used in our study for the sonication of ACS could have diluted the antimicrobial agents and that the concentration step used may have facilitated microbial growth in sonicate fluid cultures; however, in our study, sonicate fluid was not specifically assayed for antimicrobial concentrations.…”

Influence of Sonication on Bacterial Regrowth from Antibiotic Loaded PMMA Scaffolds - An In-vitro Study

“…This could lead to false negative sonication results during the diagnostics of PJI. Other studies however, see no interference in the diagnostics of PJI using sonication and antibiotic loaded PMMA 19 . Thus further clarification on using sonication fluid from sonicating standardized antibiotic loaded PMMA scaffolds, to diagnose PJI, is needed.…”