Cutibacterium Recovered from Deep Specimens at the Time of Revision Shoulder Arthroplasty Samples Have Increased Biofilm Forming Capacity and Hemolytic Activity Compared to Cutibacterium Skin Isolates from Normal Subjects.

Abstract Background Biofilm formation and hemolytic activity are factors that may correlate with the virulence of Cutibacterium. We sought to compare the prevalence of these potential markers for pathogenicity between Cutibacterium recovered from deep specimens obtained at the time of surgical revision for failed shoulder arthroplasty and Cutibacterium recovered from samples of the skin from normal subjects. Methods Forty-two deep tissue or explant isolates were compared to 43 control Cutibacterium samples obtained from skin isolates from normal subjects. Subtyping information was available for all isolates. Biofilm forming capacity was measured by inoculating a normalized number amount of each isolate into a 96-well plate. Planktonic bacteria were removed, the remaining adherent bacteria was stained with crystal violet, the crystal violet was re-solubilized in EtOH and biofilm forming capacity was quantitated by optical density. Hemolytic activity was measured by plating a normalized amount of isolate onto agar plates. Area of the colony and the surrounding area of blood lysis were measured and reported as minimal, moderate, and severe hemolysis. Results Biofilm forming capacity was significantly higher in the tissue and explant samples compared to the control skin samples (OD deep tissue 0.34 ± 0.30 vs. OD skin 0.20 ± 0.28, p=0.002). Hemolytic activity was also significantly higher in the tissue and explant samples than the control skin samples (p Conclusions Cutibacterium obtained from deep specimens at the time of revision shoulder arthroplasty have higher biofilm forming capacity and hemolytic activity than Cutibacterium recovered from the skin of normal subjects. These data add support for the view that Cutibacterium harvested from deep tissues may have clinically significant virulence characteristics. The lack of correlation between these clinically relevant phenotypes and subtype indicates that additional study is needed to identify genotypic markers that better correlate with biofilm and hemolytic activity.